(Deprecated) Slicing the Gordian Knot of SOA Governance
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(Deprecated) Slicing the Gordian Knot of SOA Governance



This document has been superseded by "Dependency-Oriented Thinking: Volume 2 - Governance and Management". Please download that instead: http://slidesha.re/1fEjz7A

This document has been superseded by "Dependency-Oriented Thinking: Volume 2 - Governance and Management". Please download that instead: http://slidesha.re/1fEjz7A



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(Deprecated) Slicing the Gordian Knot of SOA Governance Document Transcript

  • 1. “Slicing the Gordian Knot of SOA Governance”Version 0.99.1, November 2012© Ganesh PrasadThis work is licensed under Creative Commons Attribution-No Derivs 3.0 Australiahttp://creativecommons.org/licenses/by-nd/3.0/au/ Confessions of a back-to-basics SOA architect
  • 2. Table of ContentsSynopsis.................................................................................................................................6Part I – Why The Industry Is Doing SOA Governance All Wrong..........................................7 Timidity in Asserting the All-Encompassing Scope of SOA...............................................7 Confusion between Governance and Management..........................................................9 Obesity of the Governance Function...............................................................................10Part II – Elements of a Common Sense Approach..............................................................11 Recognising “Services” as a Weasel Word.....................................................................11 Back to First Principles and the Notion of “Dependencies”.............................................12 Why are Dependencies so Important?............................................................................14 Case Study 1 – Take it or Leave it: Monopsony and Choice......................................15 Case Study 2 – Culture Shock....................................................................................16 Case Study 3 – The Weakest Link of a Supply Chain................................................17 Case Study 4 – Locked Out: Key Person Risk............................................................17 Case Study 5 – The Stress and Strain of an Engineers Life......................................18 Case Study 6 – It Goes Without Saying......................................................................19 Case Study 7 – “ASSUME” Makes an ASS of U and ME...........................................20 Case Study 8 – What Makes a Good Technology Platform?......................................21 An Architectural Framework to Analyse Dependencies..................................................24 BAIT as Layers of Dependencies................................................................................24 TOGAF Artifacts as Dependency Relationships.........................................................25Part III – A Practical Guide To Governing And Managing Dependencies............................27 Agencies and Vehicles.....................................................................................................27 Key Roles....................................................................................................................27 Key Bodies...................................................................................................................30 How Many Committees?.........................................................................................32 Functions and Processes................................................................................................35 One-time Processes....................................................................................................35 Initial Dependency Review......................................................................................37 Recurring Processes...................................................................................................37 Periodic Dependency Review ................................................................................37 Remediation Program Review................................................................................37 Remediation Program Proposal..............................................................................39 BAU Program Management....................................................................................39
  • 3. New Initiative Appraisal ..........................................................................................39 Processes in Steady State..........................................................................................43Governance and Management Check-lists.....................................................................44 Classification of Dependencies...................................................................................44 The List of Check-Lists................................................................................................45 A Basic Governance Check-list...................................................................................45 A Basic Management Check-list..................................................................................46 Fundamental Enterprise Dependencies......................................................................47 Enterprise Dependency Check-lists........................................................................48 Business Layer Dependencies....................................................................................51 Modelling the Business with Domain-Driven Design..............................................51 Realism around Reuse............................................................................................52 Business Layer Dependency Check-lists................................................................55 Application Layer Dependencies.................................................................................58 Cohesion and Coupling...........................................................................................59 A Fun Exercise in Applying the High Cohesion Principle........................................62 Criteria for High Cohesion.......................................................................................66 Process, Product and Service.................................................................................68 Application Layer Dependency Check-lists.............................................................70 Information (Data) Layer Dependencies.....................................................................73 Data on the Outside versus Data on the Inside......................................................73 Aspects of Low Coupling.........................................................................................74 The Domain-specific Data Dictionary......................................................................75 The Internal Data Model (“Data on the Inside”)......................................................76 The Interface Data Model (“Data on the Outside”).................................................77 Message Data “on the wire”....................................................................................78 Information (Data) Layer Dependency Check-lists.................................................81 Technology Layer Dependencies................................................................................85 Implementing Products...........................................................................................86 Implementing Services............................................................................................86 Implementing the Nouns and Verbs of the Interface Data Model...........................87 The Three Core SOA Technology Components......................................................88 How Not to Use a Broker........................................................................................93 Implementing the Adverbs of an Operation............................................................94 Technology Layer Dependency Check-lists............................................................96
  • 4. Bringing about Desired Behaviour – Velvet Glove or Iron Hand?...................................99Summary and Conclusions................................................................................................101 Contributions of this White Paper..................................................................................102 Defining Terms...........................................................................................................102 Restoring Potential....................................................................................................102 Identifying Gaps.........................................................................................................102 Simplifying Tasks.......................................................................................................103 Doubling the Pay-off..................................................................................................103 Potential Criticism of This Approach..............................................................................104 The Weight of Tradition.............................................................................................104 Making Mountains out of Molehills............................................................................104 Drawing a Long Bow.................................................................................................105 A Bridge Too Far........................................................................................................105About the Author................................................................................................................106Acknowledgements............................................................................................................106Appendix A – SOA Governance and Management – An Issue of Definition.....................107Appendix B – Lessons from Cadet Camp (or Why SOA is Like a Snakepit).....................109Appendix C – Core Entities and Dependencies in the TOGAF 9 Model...........................111Appendix D – Artifacts In the TOGAF 9 Model..................................................................112Appendix E – References..................................................................................................115
  • 5. Synopsis“SOA Governance” as practised in the industry today suffers from three major problems:1. “SOA Governance” is wrongly understood to be the governance of SOA as an IT function, rather than the application of SOA principles to the governance of all levels of the enterprise. Most of the potential benefits of SOA as an organising principle for the enterprise therefore go unrealised because of this overly narrow, technology-focused interpretation.2. There is widespread confusion between the terms “governance” and “management” even among SOA practitioners. Many of the processes associated with “SOA Governance” are in fact routine management functions, and true governance tasks requiring direction are often neglected, resulting in costly yet preventable mistakes.3. The processes associated with “SOA Governance” (which are more often management than governance) are needlessly heavyweight. Given the overly limited scope of “SOA Governance” as mentioned in Point 1 above, these processes soak up a disproportionate share of an organisations resources without corresponding benefit.This white paper aims to do the following:1. Redefine both Governance and Management in simple and unambiguous terms so that there is no confusion between the two functions and both can be performed effectively.2. Raise the scope of SOA Governance and SOA Management beyond their current narrow technology focus so that SOA thinking can be applied at all levels to improve the agility, cost and risk profile of an organisation.3. Recommend a comprehensive yet lightweight approach involving a few core roles and bodies, a minimal set of processes and a manageable set of checklists to enable both SOA Governance and SOA Management to be performed cost-effectively. 6
  • 6. Part I – Why The Industry Is Doing SOA Governance All WrongTimidity in Asserting the All-Encompassing Scope of SOA 1“SOA Governance” does not mean the governance of SOA, any more than “scientificthinking” means “thinking about science”.We know of course that “scientific thinking” means a different way of thinking abouteverything, i.e., adopting a rigorous, analytical, evidence-based approach to understandingevery aspect of the universe without exception. Scientific thinking is about applyingscience to thinking, not the other way around.In exactly analogous fashion, “SOA Governance” is about applying SOA thinking togovernance, not about applying governance to SOA.So how does one “think SOA”?We need to understand that SOA is an organising principle that impacts every aspect ofthe enterprise. It is not a set of technology products or even an approach to deployingtechnology components. The word “technology” refers to the implementation of businesslogic2, and most “SOA Governance” activities in organisations that would describethemselves as “doing SOA” relate to implementation-related activities such as settingdevelopment and environment standards, reviewing the design of SOAP-based webservices and Business Process Management (BPM), controlling versions of services,establishing policies around the use of an Enterprise Service Bus (ESB), using aregistry/repository to centralise information about services, etc. All of these are in factroutine management activities, with a narrow focus on technology to boot. These cannotbe called SOA Governance at all!The definition of SOA we propose is “the science of analysing and managingdependencies between systems”. Systems need not be computer systems, and neitherare dependencies restricted to technology. Dependencies exist at any level of business,human relations or technology, as we will show using diverse examples. The term“managing dependencies” as used above is shorthand for “eliminating needlessdependencies and formalising legitimate dependencies into readily understood contracts”.1 Service-Oriented Architecture2 “Technology” may conjure up visions of advanced computer systems, but even a manual ledger to recordtransactions is technology. Indeed, it would seem like high technology to a race without paper! 7
  • 7. In a previous white paper published under the aegis of WSO2 (“Practical SOA for theSolution Architect”3), we showed how a solution design that is tightly coupled at the datalayer can completely negate the benefits of expensively procured SOA technology (e.g.,ESBs, registries, etc.) Such situations are unfortunately quite common becausepractitioners often take a technology-only approach to SOA and do not see thedependencies that exist between systems at different levels. The fault lies not with SOAitself but in our misunderstanding of SOA as being limited to technology. We need to startseeing SOA as a way of thinking about dependencies, not just within the technology realmor even at the level of data, but across the board. Unless we as an industry adopt“Dependency-Oriented Thinking”, the returns on our SOA investments will remainanaemic4.It would seem that industry analysts and prominent vendors have knowingly or otherwisemisled us for over a decade with the conceptual model illustrated below, and this view hasstood in the way of our ability to realise the full benefit of SOA. Every expert unfailinglyissues the standard disclaimer that SOA is not about technology, but the oppositemessage gets dog-whistled through the emphasis on products to manage web services,and ultimately prevails. In a later section, we hazard an explanation for this. Corporate Governance Corporate Resources IT Governance IT Resources SOA Governance SOA Resources Fig. 1 – The limited (and limiting) view of SOA Governance as a subset of IT Governance (itself a subset of Corporate Governance) – a view endorsed by industry thought leaders such as the Burton Group5 and IBM6.3 Downloadable from http://bit.ly/stbfiA4 In retrospect, DOT may have been a better term than SOA.5 The Burton Groups Research Director speaks on SOA and Governance: http://bit.ly/HFdF6t6 IBMs definition of SOA Governance: http://ibm.co/qm46 8
  • 8. To repeat, SOA is not a subset of IT. The benefits of SOA thinking when applied morebroadly are: 1. An improvement in business agility because of minimal dependencies between systems and consequently minimal “friction” that can impede change 2. Sustainably lower operating costs for the same reasons 3. A significant reduction in operational risk because of better-understood dependencies and fewer surprisesClearly, we have lost out on some major benefits by defining SOA as narrowly as we have.Confusion between Governance and Management“Governance” is an over-used (and abused) term. One of the unfortunate side-effects ofthe collapse of corporations like Enron and WorldCom in 2001-2002 was the suddenpopularity of the term “governance” in popular discourse. The word “governance” hasacquired such a cachet today that it often tends to be used just for effect, even when whatis meant is just plain old “management”. So lets set these terms apart right away.Governance is ensuring that the right things are done.Management is ensuring that things are done right.In spirit, governance is about the ends, or the “What”; management is about the means, orthe “How”. This is a fundamental distinction that is key to correctly implementing what werecommend in this white paper, hence it is worth spending some effort to understand thisthoroughly.An analogy with the functions of a companys board of directors and its executivemanagement will make the distinction between corporate governance and corporatemanagement more concrete. A decision on whether the company should enter a newmarket is a decision for the board, because it pertains to the fundamentals of what thecompany wants to be and whether or not the move is in the best interests of itsshareholders. In other words, this is about doing the right thing (i.e., governance).Once the decision is taken to enter a new market, executive management is responsiblefor retooling the resources of the company to enable it to compete effectively in that 9
  • 9. market. This is about doing things right (i.e., management).Governance and management decisions apply at lower levels of the organisation as well.Projects often have steering committees as well as working groups. Steering committeesare comprised of key stakeholders and they tend to make governance (i.e., “what”)decisions – objectives, scope, success criteria, etc. They also monitor adherence to theseparameters. Working groups are teams of hands-on people assigned to the project. Theymake the day-to-day management (i.e., “how”) decisions that will enable them to solveroutine problems and achieve the objectives that have been set by the steering committee.The steering committee is only concerned with the ends and not the means. The workinggroup is responsible for the means.In general, one can tell whether a given decision is about governance or aboutmanagement by thinking about how those decisions could be judged in hindsight. If theverdict is likely to be “right” or “wrong”, then its a governance decision. If the assessmentis likely to be one of a spectrum (e.g., “excellent”, “good”, “fair” or “poor”), then its amanagement decision.Obesity of the Governance FunctionOrganisations that have embraced the requirement for “SOA Governance” generally havecommittees, processes and tools to bring discipline to the way services are designed, built,deployed and managed. After all, this is how the governance of SOA is commonlyinterpreted. Some organisations have an “Integration Centre of Competence” that istasked with defining standards and controlling the introduction of new services into theecosystem.While these are sensible measures, they impose a rather high overhead especially giventheir limited technology-only focus. A centralised approving authority is an overworkedbottleneck, and so agility and operational cost are the first casualties. Many organisationsconsequently see very modest improvements in their operational cost and efficiency as aresult of moving to SOA. The economies and dis-economies largely neutralise each other,and the heavyweight governance processes shoulder a large portion of the blame.If projects in your organisation are constantly trying to find short-cuts around a centralisedauthority and a large part of this latter groups efforts are around reigning in such rogueprojects, it could be a sign that the organisation is chafing under heavyweight governance. 10
  • 10. Part II – Elements of a Common Sense ApproachRecognising “Services” as a Weasel WordNo matter how often we parrot the mantra “SOA is not about technology”, we end up with atechnology-only view of SOA while were looking elsewhere. How does this happen?Our opinion is that there is a slippery slope that we embark on once we agree to talk about“services”. From “services” to “web services”, and from web services to a technology-onlyview of SOA and SOA Governance is then just a natural progression, as illustrated below: “SOA is not about technology” “Service-Oriented Architecture is a view of the organisation as a collection of reusable services” “We should expose all business functionality through Web Services” “Its good practice to proxy all Web Services through an ESB and use a registry/repository to manage them, especially as their numbers start to grow.” “We need some governance around the use of all this technology” “SOA assets are owned by IT, so SOA Governance is an IT function” Fig. 2 – The slippery slope that leads to the view of SOA as a part of ITThere is a place for the concept of “services” in what we lightly call “Service-Oriented”Architecture. But the wide-angle lens of dependencies shows us that theres much more toSOA. We need to derive our view of “services” much more systematically and rigorouslythan we have been used to doing. So lets look at this process more closely. 11
  • 11. Back to First Principles and the Notion of “Dependencies”The four most important principles of SOA are dependencies, dependencies,dependencies and dependencies7. Were not being entirely flippant in saying this, becausethere are four distinct “layers” in an organisation where dependencies need to bemanaged. These layers, as we will explain shortly with the help of a formal framework, areBusiness, Applications, Information (Data) and Technology 8. SOA Principles (Eliminate needless dependencies between systems, formalise legitimate dependencies into well-understood “contracts”) Manage dependencies Business Layer Manage dependencies Manage dependencies Application Layer Manage dependencies Manage dependencies Information (Data) Layer Manage dependencies Manage dependencies Technology Layer Fig. 3 – The True Scope and Concerns of SOA - More than just a few Web Services managed by a section of IT!We believe that for an organisation to be effective in achieving its goals, an acceptance ofthis dependency-based view of SOA is essential. Any discussion of SOA Governance andSOA Management has to start from this basis.Since SOA is all about the management of dependencies, SOA Governance should beseen as deciding what dependencies are legitimate and SOA Management as decidinghow to manage dependencies. Both these aspects are important, so even though SOA7 To paraphrase the 3 rules of real estate: “Location, location, location”.8 This is commonly referred to as the “BAIT Model”. 12
  • 12. Governance seems to have all the mind-share, this white paper will talk about SOAManagement9 with equal emphasis. Ironically, traditional approaches to “SOAGovernance” are usually about SOA Management (i.e., the “How”).So here are our simple and readily-understandable definitions: • SOA Governance is determining what dependencies are legitimate at every layer of the organisation and identifying what existing dependencies fall outside this set. • SOA Management deals with how to remediate illegitimate dependencies at every layer of the organisation, how to formally document and communicate legitimate dependencies and how to prevent recurring violations.We will break these down into specific tasks in Part III, but for now, the following high-levelillustration will summarise how we arrive at these definitions. SOA (The science of analysing and managing dependencies) Governance SOA Governance (What are the right What dependencies are legitimate? things to do?) What existing dependencies fall outside this set? SOA Management Management How do we remediate illegitimate dependencies? (How do we do How do we formalise legitimate dependencies? things right?) How do we prevent recurring violations? Fig. 4 – SOA Governance and SOA Management at a glanceThis is the core philosophy behind our approach to SOA Governance and SOAManagement in this white paper.9 In the literature, we often come across the term Service Management. This term derives from the view of SOA as a subset of IT rather than as a set of organising principles for the entire enterprise. Our term “SOA Management” is more comprehensive. 13
  • 13. Why are Dependencies so Important?We believe that a deep understanding of dependencies makes all the difference betweena successful organisation and one that is less so. Sun Tzu said 10 many centuries ago,“Know thyself, know thy enemy – a thousand battles, a thousand victories.” By “knowing”oneself and ones enemy, he was really talking about dependencies, because strengths aswell as weaknesses are dependencies. What is it that makes you and the other guy tick?Fast cavalry? Long range artillery? What are the things that can trip you up? Lack ofsupplies (logistics)? Troops weakened by dysentery? What buttons can be pushed tomake you or the other guy behave in a predictable way? Siege of a prestigious fort?Abduction of a corps commanders son? All of these are dependencies. All of these relateto “knowing thyself” or “knowing thy enemy”.In that classic marketing strategy book of the 80s, “Marketing Warfare”, authors Al Riesand Jack Trout offer this nugget of wisdom to their clients who are looking for the mosteffective way to compete against their rivals - “Dont attack a weakness that is a weakness.Attack the weakness inherent in a strength.” Their idea is that weaknesses that are purelyweaknesses can be fixed, but weaknesses that are an inherent part of a competitorsstrength cannot be fixed without compromising that strength. As an example, they suggestthat any company trying to compete against a giant like Campbell Soup should attack notthe price of the soup (since a larger company can easily drop its prices long enough todrive a smaller competitor out of business), but something peripheral like the metal cans inwhich the giant corporation packages its products. The enormous investment in metal canpackaging is a weakness inherent in the strength of Campbell Soups scale of operations,and this investment cannot easily be thrown away. A competitor positioning themselves asusing either environmentally friendlier packaging or packaging that is less suspect from ahealth perspective would have a better chance than one competing on price.In other words, Trout and Ries suggest attacking dependencies that a competitor cannoteasily rid themselves of. Thats how important dependencies are to the life-and-deathstruggle of companies in the marketplace.To further reinforce the importance of dependencies to an organisation, we provide a fewreal-life case studies11 which clearly demonstrate two things – one, that dependencies are10 The Art of War11 The examples are authentic but have been anonymised, not so much to protect the guilty as to protect the authors and their associates from accusations of breach of confidentiality. 14
  • 14. not restricted to information technology, and two, that a lack of understanding ofdependencies can cost an organisation dearly.Case Study 1 – Take it or Leave it: Monopsony 12 and ChoiceA medium-sized commercial organisation in a developing country was experiencing stronggrowth, and began hiring more staff to meet the demands of its expanding business. Oneof its hires was a seasoned manager from another industry, and his eyes immediatelypicked up an aspect of his new employers business that its owners had been oblivious to.He was shocked to discover that although the volume of growth was strong, profits werenot growing at all. On the contrary, many of the projects were actually losing money. It tookhim very little time to home in on the problem. Almost all of the companys business wascoming from government contracts, which had been its traditional mainstay. Governmentcontracts had two features that were both very unfavourable to suppliers. One was thepolicy of always awarding contracts to the lowest bidder, which squeezed margins to thebone. The second was the one-sided payment policy, under which the bulk of the paymentfor a project would only be released on completion of the work, with a significant amountwithheld for a 12 month warranty period, leaving the supplier with a huge financing gapwhile the project was being executed and potential liability for months after completion.The newly hired manager immediately began to implement a strategy to diversify thecompanys client base. As he moved to other markets, he was able to trade in on thecompanys reputation and credibility to command higher premiums from clients in theprivate sector, generally bypassing the tender process altogether. He also concentrated onshort delivery cycles and 100% payment on completion. In four years, 30% of thecompanys business was from the non-government segment. More dramatically, 85% of itsprofits came from this segment too.Moral of the story: The company had a legitimate dependency on its reputation for qualityand reliability because it was impossible to win contracts without a good track record.However, it had developed an unnecessary dependency on government contracts throughsheer history or habit. The new manager, coming from outside the company, had no suchmental blinkers and could see this dependency that the owners werent even aware of. Hethen leveraged the companys legitimate dependency as an explicit marketing tool to win12 http://en.wikipedia.org/wiki/Monopsony 15
  • 15. new business, simultaneously reducing its unnecessary dependency on governmentcontracts with their unfavourable commercial terms. The results were spectacular.Case Study 2 – Culture ShockWhen a new General Manager took over at a company specialising in turnkey engineeringprojects, he was immediately struck by the lack of standardised process in his neworganisation. No two projects, however similar, followed the same process. Projectexecution was ad hoc and freewheeling, with lower level managers and engineers makinginformal decisions in oral negotiations with their counterparts in their client and supplierorganisations. True, the business seemed to be running smoothly, but the lack of processseemed to be a ticking time-bomb.The GM came down hard on this laidback culture. He began to insist on standardisedprocesses and timetables for all projects. Instead of informal agreements betweenoperating staff, the company began to send out formal communications of intent, spellingout what was going to be done and when, and what the other party was expected to do.Suppliers were kept on a tight leash and offered little room to negotiate on terms.Within months, dramatic results began to be seen. Project schedules began to slip. Clientsbegan to complain loudly. Suppliers were less accommodating when plans had to change.Things became bad so rapidly that the manager was fired and replaced with one of hissenior direct reports who was familiar with the old way of doing things. It took many moremonths to bring the situation back to normal.It turned out that in the turnkey engineering business, every client and every site isdifferent and requires a different approach. Flexibility is key, because there are lots ofunknowns and unexpected developments during the course of a projects execution. Twoimportant aspects of managing these changes are sufficient autonomy for local staff andmaintenance of good working relationships between key people, on the client side as wellas on the supplier side. A one-size-fits-all approach to process does not work. Neitherdoes a rigid and formal approach to managing external relationships.Moral of the story: The company had a unavoidable dependency on local and individualconditions for every project. The impacts of this dependency could only be mitigatedthrough flexibility, and this was achieved through a conscious culture of autonomy to staff“at the coalface”, mutual respect and adjustment between business partners, and regular 16
  • 16. and informal communication between key people. The new general manager wrongly sawthe informal agreements between people as a failure to formalise dependencies intocontracts, and he then tried to replace these with more standardised processes and rigidcontractual agreements, but these measures removed the cushion that the company haddeveloped to shield it from its fundamental dependency on local conditions.This case study provides a useful contrast with the previous one because what looks likean unnecessary dependency may not in fact be so. It takes astute observation tounderstand dependencies and to leverage or manage the legitimate ones while eliminatingthose that are truly unnecessary.Case Study 3 – The Weakest Link of a Supply ChainAn Australian construction company based in Sydney fabricated aluminium and timberwindows for the building industry. The company was careful to hedge against currencyfluctuations as well as the price of aluminium. But no such arrangements were in place fortimber which was sourced from a supplier based in the neighbouring state of Victoria.What the construction company didnt realise was that Chile and Malaysia are the twomajor sources of timber in the world, and that the Victorian supplier imported timberexclusively from Chile.In February 2010, a major earthquake in Chile disrupted the supply of timber, resulting inworldwide timber shortages and a steep rise in prices. Since the supplier could no longersource timber in a timely or cost-effective manner, the Windows fabricator in turn could notdeliver windows to its builders, resulting in delays, losses and unhappy customers.Moral of the story: If the construction company had looked beyond its immediateAustralian supplier and studied the entire supply chain for its products, it would haverealised the critical dependency it had on Chilean timber. Once formally recognised, itcould then have done a number of things to mitigate that dependency, such as hedgeagainst the price of timber, force its supplier to hold sufficient inventory, or diversify itssupplies across Chile and Malaysia. Since it neglected to understand and mitigate theeffects of this dependency, it paid a heavy price.Case Study 4 – Locked Out: Key Person RiskA small value-added, niche-market IT distributor had a sales team of 6 to 7 people headed 17
  • 17. by a national manager. The company had recently changed owners, and the new ownerhad not had enough time to familiarise himself with the companys customers.The national manager was suddenly poached by a competitor. He not only took his entiresales team with him, but also destroyed all records at his old company before leaving,wiping computers clean and removing all business documents.The owner was faced with the closure of his new business, since he had no records of anyof his customers. Although his national managers betrayal could have been criminallyprosecuted, he did not have the time or the resources to pursue litigation.This story did however end happily. The owner put together a fresh team under a new anddynamic national manager, and they painstakingly won back all their customers over thenext five years. The predatory competitor went bust.Moral of the story: The business had a critical dependency on its customer relationships,physically manifested as its database of customers and records of interactions with them.This dependency was not recognised and formalised as a contract, e.g., a customerdatabase that was regularly backed up and protected against loss or damage. The ownersfailure to formalise and manage this dependency cost him heavily.Case Study 5 – The Stress and Strain of an Engineers LifeA company supplying and installing power generators in buildings encountered a problemthat had not been anticipated or designed for.A generator installed in the basement of a twelve storey building was hooked up to anexhaust pipe to transport hot fumes to the outside through a shaft in the core of thebuilding. The metal exhaust pipe ran horizontally for 6 metres along the ceiling of thebasement and then turned upwards in a 90-degree L-joint to run a further 40 metres to thetop of the building through the central shaft. This was the first time the companysengineers had deployed a generator in this configuration, since all their previousengagements involved ground-level generators with short exhaust pipes.The engineers noticed a problem after installation. Whenever the generator was inoperation and began to push out hot exhaust fumes, the 40 metre column would expandwith the heat, pushing down on the L-joint and forcing the horizontal section to archdownwards almost half a metre. The pipe would return to its position once the generator 18
  • 18. stopped and the pipe cooled, but this repeated movement due to expansion andcontraction was a certain recipe for failure of the pipe due to fatigue.Ultimately, the engineers came up with a solution to replace the rigid L-joint with a muchlooser (though still airtight) bell-shaped container into which both the horizontal andvertical sections of the pipe could extend. A system of rollers allowed both sections of thepipe to expand smoothly into the “bell” and contract equally smoothly out of it, with neithersections movement impacting the other. Although the company had to spend extra timeand money to implement this solution (which they could have built into the initial designhad they anticipated the problem), they managed to avert a future, potentially moreexpensive accident.Moral of the story: The two sections of the generators exhaust pipe had an unnecessarydependency on each others thermal expansion due to the rigid L-joint between them.Once this dependency was eliminated through a more loosely-coupled expansionmechanism, the problem disappeared.Case Study 6 – It Goes Without SayingAt a large bank in the Middle East, a sincere and hard-working British expat BusinessAnalyst was put in charge of a major branch automation project. The banks tellers wereusing mainframe “green screen” terminals, and these were overdue for replacement with amore modern interface.The BA worked hard for many months, interviewing bank staff and management, gatheringrequirements, creating questionnaires for vendors, issuing RFIs and RFPs, conductingevaluations and negotiations, etc., and finally selected a vendor that seemed superior inevery respect. Although he made presentations from time to time to management to keepthem informed of his progress, he was doing everything virtually single-handed.Finally, after about a year of hard work, and just before the contract was to be awarded tothe successful vendor, the BA organised a demonstration of the branch automation systemfor the banks senior management and branch heads.Partway through the impressive demonstration, one of the managers asked, “Does thesystem support Arabic?”The BA was stunned. He turned to the vendor representative, who looked embarrassed. 19
  • 19. No, the system did not support Arabic. The commotion and head-shaking that greeted thisadmission made it abundantly clear that the deal was dead. The poor BA was later spottedsitting at his desk with his head in his hands.The search for a branch automation system had to resume almost from scratch, at a hugecost in time and money.Moral of the story: Although the BA had taken great pains to gather detailed requirementsfrom a wide cross-section of bank staff, Arabic language support was considered to besuch an obvious requirement that no one had actually spelt it out. Being a recently-arrivedexpat, the BA didnt consider it either. And so the most obvious and important requirementfor the system went unmet and ruined a years worth of work. In other words, a legitimatedependency was not formalised in the form of a contract (i.e., the requirements document).Its absence was therefore not noticed until too late and resulted in a nasty surprise.Case Study 7 – “ASSUME” Makes an ASS of U and MEA multinational systems integrator was engaged to deliver a comprehensive CorporateInternet Banking solution to a major Australian bank. Most of the functionality of theapplication would leverage the banks mainframe-based product systems, and these wouldbe exposed as services through middleware. What remained to be sourced was a suitableweb-friendly front-end product with the required rich user interface. The SI evaluated a fewpackaged products and selected one for its client.The overall project was a multi-million dollar undertaking with about a hundred peopleworking on the program. There were business analysts, project managers and a largenumber of technical staff working on the mainframe and middleware, along with a smallerteam of front-end designers and developers.It was known that the selected product had been originally designed to work against datain a relational database, but the product vendors architects had assured the SI that it wasrelatively easy to graft the front-end onto the middleware services that were being built.A few months into the project, the SIs front-end designers got their first look at the sourcecode of the front-end product, and one of them noticed references to a “Row ID” sprinkledthroughout the code. The vendors front-end developers innocently explained that thisreferred to the row number in the database. The SI team was aghast. “But theres nodatabase! You know this has to work against services talking to a mainframe!” 20
  • 20. A meeting of the SIs senior architects and project managers was hastily called. Thevendors senior architects were summoned from overseas. Not having a detailedknowledge of the code, they had not realised that the relational database assumptionwould be so deeply rooted in their products design, and they estimated that it would take afurther 3 months to fix. All knew that a 3 month delay was unacceptable to the client.Ultimately, the vendor relationship was terminated, the SIs project manager was fired, andthe SI barely salvaged the contract after demonstrating a custom-built working prototype tothe client. The fiasco threatened to derail a prestigious project and came perilously closeto rupturing a highly visible, multi-million dollar relationship between a multinationalsystems integrator and one of its biggest Australian clients.Moral of the story: The front-end application had hard-coded its dependency on arelational database into every element of its user interface. The vendors architects had notadequately documented how this dependency should have been isolated, and those whodocumented the implementation had not adequately recorded the extent of thedependency. Either of these “contracts” would have alerted people to the extent of thedependency. No wonder even the vendors architects were blind-sided.Case Study 8 – What Makes a Good Technology Platform?To round out this section, lets end with a generic example from the realm of technology –the notion of a “platform”.A platform is a technology environment that provides all the necessary run-time support forapplications. These could be virtual machines, interpreters, dynamically linkable libraries,etc. Lets look at five platforms that have been popular over the last decade and a half. i. The Windows operating system is a platform for native Windows applications. While its ubiquity was attractive to Independent Software Vendors (ISVs), there were a few problems with this platform. One was the shift from 16-bit to 32-bit around 1995, which rendered quite a few third-party applications unable to run on the newer version. Another persistent problem was known as “DLL hell”, because of the dependencies of applications on versions of dynamically linked libraries. An upgrade to an underlying system library could and often did break dozens of third-party apps. A third issue was that Microsoft exploited “undocumented Windows 21
  • 21. APIs” in its own applications that rival app vendors could not use, and so it was not a level playing field. ii. Linux (like any Unix variant) has the notion of symbolic links that it uses to advantage to manage its dynamically linked libraries (called “shared object files”). Shared object files have major version numbers and minor version numbers. Changes in minor version numbers represent changes that do not break the API. Changes in major version numbers represent changes that do break the API. Symbolic links are used to hide changes in minor version numbers but not in major version numbers, so applications that declare their dependencies in terms of the symbolic links will be shielded from irrelevant changes but rightly impacted when the API changes. Also, old and new versions of files can simultaneously exist to support old and new versions of applications.Shared Object Symbolic link Description versionlibxxx.so.2.1 libxxx.so.2 Original version that applications are dependent on.libxxx.so.2.2 libxxx.so.2 Change in shared objects minor version number is not reflected in the symbolic link, so dependent applications are (correctly) not impacted. Both shared objects can exist simultaneously, but only one is “active”.libxxx.so.3.1 libxxx.so.3 Change in shared objects major version number is reflected in the symbolic link, so dependent applications are impacted, as they should be. Both symbolic links can exist simultaneously, supporting old and new versions of applications. Table 1 – Linux and the use of symbolic links to abstract insignificant version changes iii. The Java Virtual Machine is a platform that runs Java bytecode. The Java language has undergone numerous version revisions, but the JVM has hardly changed in 15 years. Compiled bytecode from 15 years ago runs on the JVM just as well as compiled bytecode from the latest version of Java. iv. The browser is a platform too. In the mid- to late-nineties, developers were discouraged from writing applications that relied on Javascript running on the browser, because there were at least two broad variants of browser platforms – 22
  • 22. Netscapes and Microsofts – and even the versions of each browser implemented different versions of the HTML and JavaScript standards (if there were standards at all). It is only since very recently that the browser can be relied upon as a platform that will run applications in a predictable and consistent way, independent of browser vendor. v. Apples products have a reputation for ease of use, but they are also highly closed. Standard input/output mechanisms like USB ports are not supported, and very little can be achieved by a device without integration to iTunes, iCloud or both. For users who dont mind the restrictions that the Apple platform places, everything “just works”. The competing Android platform is more open, but also a bit more chaotic in terms of multiple versions and multiple implementations by device vendors.Moral of the story: For a platform to be considered a good one, applications must, aboveall, be able to rely on consistent and stable behaviour. Irrelevant changes must not beallowed to impact applications. There must be considerable latitude in the definition ofwhat constitutes a change, so that the bulk of changes within the platform can be“absorbed” without exposing applications to them. The five examples above showedvarious approaches to the construction of a stable platform, with varying degrees ofsuccess. We can see that the notion of “dependencies” underlies all of them.SummaryWe have now seen several dramatic examples of how unappreciated dependenciescaused, or threatened to cause, problems of reduced agility, increased cost and increasedrisk to organisations. Not all of these have to do with technology, much less with “SOAtechnology”, and the choice of examples has been deliberate in that regard. Yet the failureto understand the potential impact of dependencies is the common thread in all thesestories. A basic level of dependency-oriented analysis would have highlighted the costsand risks in each of these cases, saving the concerned organisations significant amountsof time, money and risk.Having therefore established the crucial importance of dependencies to an organisationsviability and success, let us see how we can approach the analysis of dependencies in asystematic way. This is what SOA Governance and SOA Management are really about. 23
  • 23. An Architectural Framework to Analyse DependenciesWe need a framework to analyse dependencies before we determine how to govern andmanage them. Rather than reinvent the wheel, lets look at some existing andwell-understood models to see if they suit our requirements.BAIT as Layers of DependenciesThe BAIT model is a popular architectural framework that decomposes an organisationinto four layers – Business, Applications, Information (Data) and Technology.BAIT has the right idea about layers, but it is traditionally focused on identifying the entitiesthat exist at each layer and the relationships between those entities. There is no strongemphasis on the aspect of dependencies, even when dealing with relationships. When weadopt the BAIT model to aid us in SOA Governance and Management, we have to adapt itto focus on dependencies, as follows: Traditional concerns of The BAIT Model applied to the BAIT Model SOA concerns Business Layer Business-Level Business Entities (Intent) Dependencies Application Layer Domain Dependencies Applications and Systems (Internal Cohesion) (High Cohesion Principle) Information (Data) Layer Interface Dependencies Domain Data Models (Interfaces/Integration) (Low Coupling Principle) Technology Standards, Technology Layer Technology Dependencies Software and Hardware (Implementation) Fig. 5 – Adapting the BAIT Model to address SOA concernsIn other words, we prefer to think of BAITs four layers as representing four “I”s, referring tothe (1) Intent, (2) Internal Cohesion (grouping of business functions into highly cohesive“applications”), (3) Interfaces/Integration between logical functions with low coupling, and(4) physical Implementation of all the components of the logical business organisation.The emphasis on cohesion and coupling is particularly relevant, as we will see in latersections. 24
  • 24. TOGAF13 Artifacts as Dependency RelationshipsThe TOGAF framework of Enterprise Architecture builds on the BAIT model and describesgeneric entities in each layer along with their inter-relationships. This is extremely valuableto us when embarking on SOA Governance and SOA Management because the hard workof understanding the components of an organisation and how they fit together has alreadybeen done.However, just like with BAIT itself, TOGAF as it stands is not a perfect framework that canbe used without adaptation to our treatment of SOA Governance and SOA Management. Itdoes not inherently support the dependency-oriented organisational transformation that wewould like to model and plan for. SOA is a single isolated chapter in The Open Groups780-page TOGAF 9 book, which betrays a traditionalist view of SOA as a subset of ITrather than as the science of analysing and managing dependencies across the board.However, nothing prevents us from using a dependency lens to view the detailed set ofentity relationships identified by TOGAF and derive a more applicable model for ourrequirements. Well show how to do that in Part III of this document.TOGAF defines some core concepts at the four layers and lists out some important andstandardised documents (“viewpoints” in the TOGAF terminology) that provide usefulinformation about these concepts and their interactions. TOGAF uses the term “catalog” torefer to any list. Similarly, it uses the term “matrix” for tables that show the relationshipbetween exactly two concepts, and “diagram” for any depiction of how more than twoconcepts are related. (a) (b) (c) Fig. 6 – (a) a TOGAF “catalog”, or list of entities; (b) a TOGAF “matrix”, or table of two-entity relationships; (c) a TOGAF “diagram”, or a depiction of multi-entity relationships.If we interpret “relationships” as “dependencies”, matrices become two-entitydependencies and diagrams become multi-entity dependencies. The set ofTOGAF-defined matrices and diagrams at each of the four BAIT layers then gives us aready-made check-list of the dependencies we need to be mindful of within those layers aswell as between layers.13 The Open Group Architecture Framework: http://www.opengroup.org/togaf/ 25
  • 25. We consciously adapt TOGAFs set of artifacts to align them with a SOA view of theenterprise because TOGAF is not inherently dependency-oriented. In other words, theentity dependencies we study will correspond to our SOA version of the BAIT Model ratherthan the traditional one. SOA Version of BAIT Model TOGAF Artifacts Business Layer Business-Level (Intent) Dependencies Application Layer Domain Dependencies Core entities, (Internal Cohesion) (High Cohesion Principle) Two-entity dependencies and Information (Data) Layer Interface Dependencies Multi-entity (Interfaces/Integration) (Low Coupling Principle) dependencies Technology Layer Technology Dependencies (Implementation) Fig. 7 – TOGAF artifacts classified by BAIT levelWe can now begin to see why the traditional view of “SOA Governance” is so limited. SOA Governance SOA Management (“What dependencies are (“How do we manage legitimate?”) dependencies?”) Business Traditional “SOA Governance” concerns Application Development and environment Information (Data) standards, reuse metrics, Web Service version management, repository structures to store Technology WSDL, schema and policy files, etc. Fig. 8 – Traditional “SOA Governance” concerns are more correctly SOA Management, and a subset at that. Little effort is focused on the governance question, “What dependencies are legitimate?”Clearly, our entire approach needs nothing less than an overhaul. Its time to look at howSOA Governance and SOA Management should in fact be done. 26
  • 26. Part III – A Practical Guide To Governing And Managing DependenciesIn the previous two parts of this white paper, we critiqued the industrys approach to SOAGovernance and suggested how we could do it better by considering the elements of amore rational approach based on the analysis of dependencies.In this part of the white paper, we will show how to put these elements together into alightweight method. Well recommend some key roles and bodies that will be responsiblefor the functions of SOA Governance and SOA Management, the minimal set of processesthey need to carry out, and a manageable set of check-lists that they should use for thesepurposes.Agencies and VehiclesKey RolesWe believe that the primary agency to apply dependency-oriented thinking at every level ofan organisation is the Enterprise Architecture function. In organisations with an EnterpriseArchitecture group, there are usually architects with specialised skills who are tasked withdefining the business architecture, application architecture, data architecture andtechnology architecture, so the BAIT Model is already an operational tool. Thesespecialised architects are the people who need to spearhead a new way of approachingSOA Governance and SOA Management.The role of Enterprise Architecture under this model is to analyse the four layers of theorganisation specifically from a dependency focus, first to determine the “what” (thelegitimate dependencies that should exist at each level as well as the unnecessary onesthat do currently exist) and then to guide the “how” (the programs of work required to alignthe organisation to the set of legitimate dependencies that were identified).One of the suggestions we have for the Enterprise Architecture function to assist them intransitioning to this world-view is to include professionals from certain other disciplines,even if on a part-time basis. Project Managers, Risk Managers and Contract Lawyers areall used to looking for dependencies in their own areas, and they can inject some of thefresh blood that the traditional Enterprise Architecture group needs to make them effectivein a SOA sense. 27
  • 27. In organisations with a reasonably effective architecture function, heres how businessintent is transformed into working systems today: Fig. 9 – Key roles and their traditional concernsHeres the subtle but important change we would like to see: Fig. 10 – Key roles and their recommended concernsIts not as if architects dont already think about dependencies. Its just that dependenciesneed to be promoted to be a primary, top-of-mind item in all discussions and decisions, 28
  • 28. especially where the business and IT are involved. Every individual who is part of thedecision chain from business objective to implementation, no matter what their level,needs to be sensitised to the importance of dependencies. Thats what it means toinculcate “SOA Thinking” within an organisation, and architects need to don the mantle ofevangelists to spread this philosophy.The perspectives of project managers, risk managers and contract lawyers could be veryuseful additions to their skill set, since these give them a “fresh pair of eyes” with which torecognise the diverse set of dependencies impacting the enterprise.SOA Governance and SOA Management become far easier to execute when theorganisational culture understands the importance of dependencies. 29
  • 29. Key BodiesWhile the Enterprise Architecture function is key to our recommended approach, SOAGovernance and SOA Management require the active participation of many different rolesand functions to be effective. The business and IT are crucial stakeholders, as we saw. It isessential to involve multiple roles in the SOA Governance and SOA Managementfunctions, and this calls for new organisational structures. We are all too aware of thereputation of committees as inefficient bureaucracies 14, but the multi-disciplinary nature ofthe tasks at hand, together with the fact that these are ongoing responsibilities, dictate theneed for one or more standing bodies rather than ad hoc teams. Broadly, two groups ofpeople are required to carry out the required functions: • a “Dependency Governance Committee” • a “Dependency Management Committee”Now this is a functional classification, and these two logical groups could be realised asseveral physical committees, e.g., one or more at each level of the BAIT model plus one atthe Enterprise level. Some committees could also take responsibility for more than oneBAIT layer, as long as they are clear which layer they are dealing with at any given time.The decision on how many physical committees to have is entirely up to the organisationin question, but we would strongly recommend against combining governance andmanagement functions within any single committee. That would defeat one of our primarygoals, which is to perform both functions effectively and without confusion.Additionally, although its the committees functions that are important and not their names,we would recommend that the term “dependency” be explicitly used in their names inorder to inculcate a dependency focus within every person in the organisation. Weve losta decades worth of benefits thanks to poor naming (“Service-Oriented” as opposed to“Dependency-Oriented”), so lets call a spade a spade this time, however corny it maysound. A committee should either be a “Dependency Governance Committee” or a“Dependency Management Committee”, with prefixes as appropriate to the BAIT leveland/or business unit.14 Two of our personal favourites are “A camel is a horse designed by a committee” and “A committee is a group of people who individually can do nothing, but who get together to decide that nothing can be done.” 30
  • 30. In a nutshell,• The Dependency Governance Committee is responsible for defining which of the dependencies at the level they are responsible for are legitimate and which are not. They are also responsible for prioritising the programs of work to remediate dependencies.• The Dependency Management Committee is responsible for costing, planning and initiating the programs of work that will bring and keep the organisation in line with the model validated by the Dependency Governance Committee and according to the priority decided by that committee.The Dependency Governance Committee should have a fair representation ofEnterprise Architects, with specialists in each of the BAIT layers. At least some of themembers of the Dependency Governance Committee should have a background in one ofthe non-IT professions listed earlier 15, because these professionals are trained to look fordependencies. Depending on the layer of the BAIT model that the committee isresponsible for, there should be representation from senior executives, businessmanagers, functional heads and technology specialists. This may mean separatecommittees, or a single committee with some fixed members and a number of others whoattend only the sessions that are relevant to them.Importantly, the Dependency Governance Committee must have authority and access tofunding to be able to approve programs of work, otherwise the organisation will be unableto remediate the dependencies identified as invalid. One of the reasons why we expendedso much ink in Part II to present 8 separate case studies was to hammer home the ideathat attention to dependencies saves real money. Business unit heads should therefore notbe churlish about funding dependency remediation tasks, and their representation onGovernance committees serves more than just a decorative function!The Dependency Management Committee should comprise people skilled in costing andplanning, typically project managers and functional heads. They may need representationfrom Enterprise Architecture to keep them focused on the dependency aspect while theyattend to their more familiar roles of costing and planning programs of work. Again, therewill be a need to have different people engaged for different layers of the BAIT model, sothere could be considerable variety in the structure and/or composition of thecommittee(s).15 Project managers, risk managers and contract lawyers. 31
  • 31. How Many Committees?The dependency governance and management functions can be performed by just twocommittees in a small organisation, since they can do justice to the complexity of the entireorganisation themselves. As organisations become larger, the committees will need tobecome more specialised, as the following examples illustrate. Dependency Governance Dependency Management Committee Committee Fig. 11 – Committees for a small organisation Enterprise Dependency Enterprise Dependency Governance Committee Management Committee Business Dependency Business Dependency Governance Committee Management Committee Application & Information Application & Information Dependency Governance Dependency Management Committee Committee Technology Dependency Technology Dependency Governance Committee Management Committee Fig. 12 – Committees for a medium-sized organisation Enterprise Dependency Enterprise Dependency Governance Committee Management Committee Business Dependency Business Dependency Governance Committee Management Committee Application Dependency Application Dependency Governance Committee Management Committee Information Dependency Information Dependency Governance Committee Management Committee Technology Dependency Technology Dependency Business Governance Committee Management Committee Units / Geographies Fig. 13 – Committees for a large organisation 32
  • 32. If this set of committees is beginning to look too bloated, our audacious claim is that theseare the only governance and management structures that an organisation will ever need,so this could in fact represent a drastic simplification to the plethora of managementbodies that currently exist in a given organisation.Lets look at a few special cases to support this claim.Security dependencies: Security is an important aspect of business operations, andinformation security traditionally tends to be treated as an IT concern. However, securityconcerns are relevant at different levels of the BAIT model. Perimeter security, forexample, may be relevant only at the level of technology, since it is completely opaque tohigher layers. Data Leakage Protection applies at all levels from the business layer down,since it is impacted by business processes, application design, data interchange as well astechnology-related aspects like USB device control and disk encryption. PCI-DSS 16compliance requirements may or may not impact business processes but will certainlyimpact application design, data storage and encryption/tokenisation technology. Thedependency governance and management committees at these various levels will addressand manage the security concerns listed above, as well as any others that arise from timeto time.Non-technology domains that are not line-of-business, such as Human Resources,Accounting, Finance or Legal, also fit into this dependency-oriented model.Human Resources dependencies: Clearly, an organisation that employs many morecontractors than permanent employees has a very different dependency profile than onewith the opposite composition. The contractor-based organisation can downsize morereadily in an economic downturn and re-hire when required, but it has a more tenuous holdon IP due to the less “sticky” nature of employee knowledge. The contractor-basedorganisation will have to invest more heavily into knowledge-management systems tomitigate against their risk of losing critical business and operations knowledge. Theorganisation with a higher proportion of permanent employees will have to be morecautious about hiring in an economic upturn because of their larger financial exposurearising from retrenchment benefits they may have to pay out when downsizing. A businessdependency governance committee and business dependency management committeefocused on the HR business unit will be able to formalise these concerns and evolvemitigating strategies.16 Payment Card Industry Data Security Standard 33
  • 33. Finance dependencies: An organisation that is funded mainly by debt has a differentdependency profile to one funded mainly by equity. A debtor and a creditor representdependencies of different kinds, and every financial instrument that is issued or purchasedimposes a different flavour of dependency on the enterprise. Financial controllers makedecisions based on such dependencies all the time, whether or not they use the word“dependency”. Regardless, the business dependency governance and managementcommittees for the Finance business unit will standardise these functions in a consistentcorporate style.In short, these varied examples support our claim that SOA, being all about dependencies,is not about technology but is an organising principle for the enterprise and lends itself to asimple and consistent form of governance and management. Form follows function, andthe structure of the required governance and management committees follows thediscipline of dependency-oriented thinking.[It may be argued that the bulk of a modern enterprises business logic tends to be codedinto software-based systems with very little residual manual processing, so “its all ITanyway”. Let us refute this argument with a simple analogy. Just because all legaldocuments in a country are in the English language does not imply that a mastery ofEnglish is all that is required to understand or to draft legal documents. One needs tounderstand law. In similar fashion, even if every piece of business logic in an organisationis implemented within a technology platform, understanding how to govern and managetechnology alone is not sufficient. The principles behind how business logic and businessdata are identified and organised need to be understood, and the analysis ofdependencies is a crucial tool to achieve this understanding.] 34
  • 34. Functions and ProcessesBroadly speaking, the processes required for SOA Governance and SOA Management areeither one-time or recurring.To keep an otherwise dry topic light and readable, we will illustrate what occurs duringeach of these processes through imaginary conversations between various parties. Theplayers in all these scenarios are the following:G – Dependency Governance CommitteeM – Dependency Management CommitteeB – Any Business UnitOne-time ProcessesWhen an organisation embarks on doing SOA Governance and Management the way thiswhite paper recommends, there will be a one-time activity (which could of course bebroken up into phases for manageability) on the part of the Dependency GovernanceCommittee to do two things:1. Agree on the set of approved dependencies at each level of the organisation as suggested by the BAIT model;2. Identify the dependencies that actually exist, specifically the ones that fall outside the set of approved dependencies above.The latter list (the set of actual dependencies that are not approved) is the input to theDependency Management Committee to plan a program of work to remediate. 35
  • 35. Governance Functions Management Functions Publication: List of Approved Dependencies One-Time Dependency List of Dependencies to be remediated Review Update: List of Approved Dependencies Need not Periodic Remediation align toReview Dependency Program Business cycle Review Proposal Project List of cycle Dependencies to be remediated List of programs, Remediation grouped and costed Program Review Business Business Requirements Driver (Objective) Initiative Details New New Business Initiative Initiative Project Review Proposal cycle Non-approval: List of Dependencies in violation Update: List of Approved Dependencies Approval BAU Program Management Approval: Prioritised list of programs, with funding Report: Dependencies remediated Dependency-related Process Existing Business Process Fig. 14 – Dependency Governance and Management Processes 36
  • 36. Initial Dependency ReviewScenario 1:G: “Weve done a review and decided that the only legitimate dependencies are these.There are many actual dependencies weve found in our systems that are not in thisapproved set. They need to be eliminated.”M: “OK, well come back with a proposal for a program of work to remediate them.”Recurring ProcessesThere are recurring processes within both the governance and management functions.Recurring governance processes are reviews to re-validate the set of legitimatedependencies at any level and to identify afresh the set of existing dependencies that falloutside of this approved set. The latter set (which is expected to shrink with each iteration)is then an input to management committees to initiate programs of work to remediate.Prioritisation and approval of these proposed programs of work is also a governancefunction.Periodic Dependency ReviewScenario 1:G: “Given the changing nature of our business since the last review, some newdependencies are now deemed legitimate and some old ones no longer are.”M: “OK, well make a note of the new set of approved dependencies and come back to youwith a proposal for a program of work to eliminate the ones that are no longer approved.”Scenario 2:G: “Some new dependencies that are not in the approved list seem to have “snuck into”our systems since our last review. These need to be eliminated ASAP.”M: “We dont understand how that could have happened. Well come back to you with aproposal for a program of work to remediate them.”Remediation Program ReviewM: “Weve put together a proposal for a set of programs that will remediate the unapproved 37
  • 37. dependencies that you identified. Weve worked out the costs and benefits of each ofthem. Please tell us how you would like to prioritise them for execution, and pleaseapprove funding for the ones you want done in the current period.”G: “We think you should initiate the following subset of programs in the current reportingperiod and defer the remaining for a future period. The funding for the programs in thecurrent period is hereby approved.”M: “Well initiate these programs right away.” 38
  • 38. Recurring management processes are intended to identify programs of work to remediatethe invalid dependencies identified by the governance committee(s) and to manage theseprograms once approved by them.Remediation Program ProposalScenario 1:M (internal conversation): “Given the set of existing dependencies that were identified bythe Dependency Governance Committee as not being on the approved list, lets work outthe costs and benefits of eliminating them, and group these tasks into cohesive programsof work for them to prioritise and approve.”BAU Program ManagementOnce a Dependency Remediation Program is approved, it is managed in exactly identicalfashion to regular business projects. These are not to be treated as projects of secondaryimportance or nice-to-haves because of a mistaken characterisation of SOA as technology.On the contrary, the involvement of business and technology representatives and properpositioning of the benefits of these initiatives by Enterprise Architecture should ensure thatthey are taken equally seriously as programs initiated by the business. After all, unfixeddependencies mean significant amounts of real money, as we have seen earlier.The business initiatives detailed in the next section also feed into Business-As Usual(BAU) program management alongside dependency remediation programs.The standard discipline of conducting Post-Implementation Reviews (PIRs) to evaluate thesuccess of a program should be conducted for dependency remediation initiatives as well.Granted, the benefits are not always immediate but recurring, but it should be possible toassess if the dependencies slated to be eliminated were in fact removed, and a freshassessment of the costs and benefits of the initiative should be conducted to report back tothe Dependency Governance Committee.New Initiative AppraisalAn event that could trigger a fresh governance activity is when there is a business driver(objective) necessitating a program of work, the proposal is put forward, and thegovernance committee evaluates if this introduces any fresh dependencies that are not onthe approved list. (Of course, any additional dependencies may be justified, in which case 39
  • 39. the approved list is updated, or may even make some existing dependencies unnecessary,which again results in updates to the approved list). The proposal may need to beamended to avoid introducing dependencies that are not approved.A new initiative could be on the business side (e.g., entering a new market, introducing anew product, acquiring a company, outsourcing or re-insourcing a business function,changing a business process, signing up a new partnership, etc.)The initiative could also be on the technology side (e.g., buying and installing a newproduct system, developing a new system in-house, outsourcing or re-insourcing atechnology function, changing the technology implementation of a function or process,decommissioning a system or application, undertaking a turnkey project, etc.)All of these changes have dependency implications that have to be reviewed before theinitiatives concerned can be approved. A large part of the technical and business “debt”that is incurred by organisations is due to a failure to assess new initiatives for theirdependency implications.The following process is meant to plug that loophole.Scenario 1:B: “Heres our proposal for a new project.”G: “It appears that your project is about to eliminate some dependencies. Thats good.Project approved.”B: “Thanks, well initiate the project.”M: “Well make a note that the set of approved (and existing) dependencies will shrink afterthis project.”Scenario 2:B: “Heres our proposal for a new project.”G: “Your project introduces a new set of dependencies, but they do seem to be valid, sowell expand the set of approved dependencies. Project approved.”B: “Thanks, well initiate the project.”M: “Well make a note of the expanded set of approved dependencies.” 40
  • 40. Scenario 3:B: “Heres our proposal for a new project.”G: “Your project will introduce new dependencies that are not valid. Were afraid we cantapprove it. Go back and re-think your processes and/or designs so that they stay withinthe set of approved dependencies.”B: “OK, well get back to you with a reworked proposal.”M: (“Nothing for us to do.”)Incorporating a Dependency Focus into New Initiative AppraisalThe business case for any program of work should include its impact on dependencies(positive or negative), in addition to the standard calculations of cost-to-implement andbusiness benefit. Dependencies carry a hidden yet heavy cost in terms of business agility,operating cost and operational risk, so we would like to have these made explicit andbrought to the notice of approving authorities. Introducing dependencies (legitimate or not)incurs cost and risk, and removing them has the opposite effect. This is where the workdone by governance committees in identifying dependencies will form a useful input. Thefollowing page has a simplified form that illustrates this. 41
  • 41. New Initiative Appraisal Form Cost Business Benefit Dependency impacts (+/-) Description of proposed project CapEx OpEx (3 Yrs) Business agility Operating costs Operational risk (3 Yrs) (3 Yrs) (3 Yrs) assessment Remove replication of customer (200,000) (25,000) 90,000 50,000 80,000 Changes from address data by consolidating it (25,000) 90,000 50,000 80,000 medium to low within system X where it belongs (25,000) 90,000 50,000 80,000Approved by:Approval date: Fig. 15 – An indicative format for a “New Initiative Appraisal Form”The form above illustrates how the hidden benefits from the removal of dependencies (or conversely, the hidden costs of introducingfresh dependencies), once quantified, could sway the business case for a project either way. In this example, the business case for aproposed project doesnt by itself stack up because the total business benefit over a 3 year ROI horizon ($270,000) is less than the costincurred ($275,000). However, the benefit goes up enormously once the improvements to the organisations agility, cost and risk profileare taken into account. A dependency focus therefore drives behaviour that is desirable over the longer term.This is the kind of change we would like to see in the way organisations evaluate programs of work. It represents a “least-dependency”model of doing business which keeps them lean and low-risk.
  • 42. Processes in Steady StateThe recurring processes around dependency review followed by remediation are expectedto wind down as the culture of dependency-sensitivity begins to take hold and the numberof exceptions correspondingly reduces.In steady state, the only processes that we are likely to see are New Initiative Proposal,New Initiative Review and BAU Program Management, since these processes willsubsume the dependency-related activities that are the sole focus of the other processes.Periodic Dependency Reviews will still take place, but with any luck, no deviations willhave occurred and hence no remediation programs will need to be initiated. Governance Functions Management Functions Business Business Requirements Driver (Objective) Initiative Details New New Business Initiative Initiative Project Review Proposal cycle Non-approval: List of Dependencies in violation Update: List of Approved Dependencies Approval BAU Program Management Dependency-related Process Existing Business Process Fig. 16 – Ideal Dependency Governance and Management Processes in “Steady State” 43
  • 43. Governance and Management Check-listsWith our governance/management bodies and processes in place, its time to look at whatthey will actually do. Here is a recommended approach based on a detailed analysis oforganisational layers along with a sample check-list of questions for the committees to ask.Classification of DependenciesConsider a set of dependencies between entities within a BAIT layer (or across layers). Entity 1 dependency 1 dependency 3 dependency 2 Entity 4 Entity 3 Entity 2 dependency 4 Entity 5 Fig. 17 – An unclassified set of dependenciesThese dependencies may be further categorised into (say) two broad groups because theyare themselves related in some way. A governance or management committee may thenassign responsibility for these two dependency groups to two separate teams. Dependency Group 1 (covers dependencies 1 and 2) Entity 1 dependency 1 dependency 3 dependency 2 Entity 4 Entity 3 Entity 2 dependency 4 Entity 5 Dependency Group 2 (covers dependencies 3 and 4) Fig. 18 – Dependency Groups containing cohesive sets of dependencies 44
  • 44. The Dependency Governance Committee(s) and Dependency Management Committee(s)may want to organise themselves into specialised teams to study and monitor smaller,cohesive sets of dependencies. We will call this intermediate level of granularity (i.e.,somewhere between a single dependency and all the dependencies that may exist at aBAIT layer) a “Dependency Group”. Although not identified in TOGAF, a DependencyGroup helps to provide a “system” view of related dependencies.In the following sections, we will document not just the set of dependencies suggested byTOGAF at each BAIT layer, but also our suggested classification of these dependenciesinto Dependency Groups that can be assigned to specialised teams as their responsibility.The List of Check-ListsOur check-lists will be numbered according to the following scheme: G(overnance) M(anagement) Basic G-00 M-00 E(nterprise) EG-00 EM-00 B(usiness) BG-00 BM-00 A(pplication) AG-00 AM-00 I(nformation) IG-00 IM-00 T(echnology) TG-00 TM-00A Basic Governance Check-listRegardless of the level of the BAIT model at which governance is sought to be applied,there are some standard questions that will need to be asked:G-01 What are the core entities involved?G-02 What are the legitimate dependencies between them?G-03 What dependencies can we identify in the current situation that fall outside this set of legitimate dependencies?There will of course be more specialised governance questions depending on the BAITlayer concerned, and we will cover them under the appropriate sections. 45
  • 45. A Basic Management Check-listIn similar fashion, there are some standard management questions that need to be askedat every level of the BAIT model:M-01 How do we express the dependencies between entities as suitable contracts?M-02 How will we enforce contracts?M-03 How will we monitor adherence to contracts?M-04 How do we re-engineer our existing systems to align them with the target model?Every BAIT layer will add its own specialised management questions to this list, and wewill examine each under its corresponding section.When an organisations governance and management committees are staffed withappropriate experts and when they adapt to the dependency-oriented way of thinking, theywill be able to formulate more relevant questions to add to these check-lists. 46
  • 46. Fundamental Enterprise DependenciesBefore we even go into the four BAIT layers, we need to understand some fundamentaldependencies at the overall organisational level as illustrated below. The reason why the“enterprise” has been split from even the business layer is that most organisations arehighly silo-ed at the business unit level (from immediately below the CEO). Henceenterprise concerns need to be addressed at a level higher than those of business units. Statement of Purpose Goal vision and alignment mission Value Chain responsibility external External Stakeholder assignment Enterprise dependencies Entity Core Roles governing principles Business Principle Architectural Principle Policy Framework Fig. 19 – Dependencies and Dependency Groups at the Enterprise level (TOGAF)The Dependency Governance Committee at this level is necessarily high-powered. Itshould consist of the Head of Architecture and the CIO engaging with the CEO andexecutive management. This is the only body that can authoritatively decide on thelegitimate dependencies at the enterprise level. 47
  • 47. The Dependency Governance Committee should review these dependencies on a periodicbasis, perhaps half-yearly. Any deviations in practice should be referred to a DependencyManagement Committee which may consist of the executive management and their directreports. The Dependency Management Committee will be responsible for bringing theorganisation back into alignment with the approved set of Enterprise dependencies.Enterprise Dependency Check-listsThe four broad Dependency Groups at the fundamental Enterprise level are as below, anddifferent skill groups may be engaged to deal with each:1. The Statement of Purpose associates the enterprise with its goals through vision andmission statements. The vision is the enterprises opinion of what its Utopia would looklike. The mission defines the role the enterprise asserts for itself to bring about that visionof Utopia.Sample Governance Questions:EG-01 What is the Enterprises concept of Utopia?EG-02 What is the Enterprises role in bringing about that vision of Utopia?Sample Management Questions:EM-01 How do we justify our concept of Utopia?EM-02 How do we communicate our concept of Utopia?EM-03 How do we execute our self-appointed role? (The answer to this question creates the foundation of the business architecture.)2. The Value Chain describes the dependencies between the enterprise and importantexternal entities.Sample Governance Questions:EG-03 What are the dependencies that external entities have on the enterprise? (This is the reverse of the basic governance question of what dependencies the enterprise has on external entities.) 48
  • 48. EG-04 What alternative external entities can feasibly replace our current ones without impact?EG-05 What abstract external entities do we have a dependency on (e.g., the economy, the regulatory environment)?EG-06 What external entities may also be considered partially internal (e.g., head office, subsidiaries)?EG-07 What time-bound contractual obligations currently exist (that can be re-negotiated at an appropriate juncture)?Sample Management Questions:EM-04 How do we reduce the leverage that external entities have over us?EM-05 How do we increase the leverage that we have over external entities?3. Core Roles describe how responsibilities are assigned to stakeholders within theenterprise, usually through a RACI/RASCI 17 model.Sample Governance Questions:EG-08 What gaps currently exist in the set of stakeholders in terms of responsibility assignments?EG-09 What overlaps currently exist in the set of stakeholders in terms of responsibility assignments?EG-10 What set of stakeholders (in terms of responsibility assignments) best covers the requirement, including concerns like key person risk, dual controls, oversight, succession planning, etc.?EG-11 What is the alignment between stakeholders and enterprise goals (when viewed through the prism of responsibility assignment)?17 RASCI – R(esponsible), A(ccountable), S(upports)/S(ponsors), C(onsulted), I(nformed). This is a model of responsibility assignment that usually takes the form of a matrix and visually displays the coverage of responsibilities across roles. There are many variants of this. 49
  • 49. Sample Management Questions:EM-06 How do we describe stakeholder responsibilities for the purposes of hiring as well as performance measurement?EM-07 How do we measure the performance of stakeholders towards the achievement of goals?EM-08 How do we detect and compensate for failures to adhere to assigned responsibilities?4. The Policy Framework defines a set of principles or values that will guide how theenterprise will set about meeting its goals. These cover both business principles (e.g., “wewill never create a conflict between our distributor network and our direct sales channels”)and architectural principles (e.g., “Our policy towards acquiring new capability is to reusebefore we buy, and to buy before we build”).Sample Governance Questions:EG-12 What is the priority to be applied to policies in case of a conflict?EG-13 What specific stakeholder roles will be responsible for formulating and maintaining policies of various kinds?Sample Management Questions:EM-09 How do we measure and monitor adherence to policies?EM-10 How do we determine if a policy is outdated or not applicable in a given situation?EM-11 How do we intimate the responsible stakeholders of a possible need to modify policies when the situation demands?The fundamental enterprise dependencies need to be studied with great care by executivemanagement (aided by the CIO and the Head of Architecture). These dependencies andthe way the enterprise decides to manage them will determine the shape of the businesslayer as well as all lower layers. 50
  • 50. Business Layer DependenciesThe Business Layer is really where the shape of the organisation is decided, in a mannerof speaking. Here is where the business intent in terms of the vision and missionstatements is analysed for its implications in terms of the functions, processes and processsteps (operations) that will need to be implemented.Once the Business Architecture is done, the rest is a matter of placing related entitiestogether, housing them somewhere and executing codified logic. Thats really all there is toit, although much of the Sturm und Drang in any typical organisation seems to happen atthese lower layers.Modelling the Business with Domain-Driven DesignOur recommended way to approach the business, application, information and technologylayers is to use the method popularised by Eric Evans – Domain-Driven Design (DDD),an all-encompassing methodology that is a joint venture between business andtechnology.DDD introduces another aspect that traditional SOA practice doesnt seem to consider, –the need to develop a “ubiquitous language” to describe the domain, and to unite bothbusiness and technology realms through the use of this ubiquitous language. At onestroke, the ubiquitous language defines both the high-level data model and high-levelprocess model for all the business functions of the enterprise. Using a quick first pass ofDDD, it is possible to make reasonably insightful decisions on the right entities of eachtype that should exist at the business level.The logical progression in modelling the business is as follows:Vision => Mission => Business Functions => Processes => Process Steps (Operations)The types of entities at the business layer and their relationships are illustrated in thefigure above. DDD helps to determine the appropriate instances of each type. 51
  • 51. Realism around ReuseOne of the much-ballyhooed benefits of SOA is the notion of reuse, although you willnotice that this white paper has been very understated about it. True, we have talked aboutimproved agility and reduced operating cost, both of which are well-served if businesslogic can be reused rather than reinvented. But reuse itself is not a first-class benefit. It isa means to an end rather than an end in itself.We do need to understand the nature of reuse and the limits to which we can reasonablyexpect to reuse operations, because traditional SOA practice has created unrealisticexpectations about reuse that are often belied.The Business Layer is where the potential for reuse of operations first suggests itself. Thedetermination of the right processes to support defined business functions, and the furtherdecomposition of processes into steps or operations, will often yield sets of operations thatare remarkably similar in their function. Common sense would suggest reusing suchoperations rather than creating multiple versions of essentially the same operation.However, this suggestion is based on very high-level contours of the operations inquestion. The potential for reuse needs to be assessed more critically at the ApplicationLayer and Information (Data) Layer before it can be turned into implementation reality atthe Technology Layer.The reason for our seeming pessimism is that operations that appear the same may not infact be reusable in different contexts. It is not the operation itself that determines thefeasibility of reuse. We will see that the internal and interface data models create a specificcontext for an operation. Unless the various contexts for an operation can be readilyabstracted through mechanisms like the judicious use of common super-types, reuse willnot be feasible. So although we have seen a fair degree of functional reuse in our ownexperience, it is best not to burden an initiative with overly high expectations. Reuse is nota guaranteeable metric.The following diagrams illustrate this situation. 52
  • 52. Fig. 20 – An analysis of the operations (process steps) that follow from the identificationof the organisations vision, mission and business functions in the Business Layer may suggest candidates for reuse. However, this is only a tentative identification.Fig. 21 – After analysis at the Application and Information (Data) Layers, some of theseoperations may be confirmed to be reusable, while others turn out to be too different in their contexts to be reused, in spite of superficial functional similarities 53
  • 53. The fundamental business layer dependencies to be understood are illustrated below. Business Footprint Goal Organisation Decomposition vision Location placement Organisational Role Actor Unit identity mission behaviour Business Function logical Event realisation triggers Process interaction coordination Process Step (Operation) Use Cases and Process Flows data life-cycle Data implementation Technology Component Fig. 22 – Dependencies and Dependency Groups at the Business Layer (TOGAF) 54
  • 54. Business Layer Dependency Check-listsThere are three broad Dependency Groups that emerge at the business layer, and theyare discussed below.1. The Business Footprint is a related set of entity dependencies that acts as atraceability tool to map how the enterprise achieves its goals through every layer from thebusiness down to technology. It describes the responsibility of each organisational unittowards achieving the vision of the enterprise, and the organisational units businessfunctions that are derived from its vision statement. It also follows the business functionsthrough to the level of processes and the logical steps (operations) that these processescoordinate. [At the lowest levels, a fully fleshed-out business footprint diagram shows whatdata elements are involved in an operation and what technology components implementthese functions and process/store this data. However, at the business layer, this level ofdetail is neither available nor necessary to consider. Work needs to be done at the dataand technology layers to flesh out these aspects of the business footprint diagram.]The Business Footprint Diagram in the TOGAF model is one of the most importantdescriptions of how the organisation functions. It is usually not a single physical diagrambut a logical one spread across multiple physical ones, and requires a multi-disciplinaryteam across multiple business units to fully document.Although the creation of the Business Footprint Diagram is very tedious and difficult, thereare rich rewards to be enjoyed once it is created. This comes closest to a “control panel” or“dashboard” for the enterprise, because it is possible to drill up or down to any level tounderstand the implications of a change or disruption to all related systems. It is also thefoundation for the application, information and technology layer models.Sample Governance Questions:BG-01 What is the extent of functional duplication at each level?BG-02 What is the abstraction hierarchy for entities that describes how a single logical function gets specialised into multiple concrete variants? (e.g., an abstract Customer entity that has Corporate Customer and Retail Customer as its subtypes forms the basis for postulating common functions such as Registering a New Customer, which will necessarily have specialised variants for its concrete subtypes.) 55
  • 55. BG-03 What are the factors that drive differentiation between the multiple concrete variants of a single logical function?Sample Management Questions:BM-01 How do we plan programs of work at every level to align our current footprint to the ideal one? (This is a high-level question that will spawn more detailed questions as one drills further down.)2. Organisational Decomposition shows how organisational units are distributed invarious geographical locations. It decouples identity from behaviour through its definition ofactors and roles, and shows how roles relate to business functions as well as toorganisational units and locations.Sample Governance Questions:BG-04 What is the organisation structure that best reflects the functional make-up of the organisation? What level of centralisation/federation is appropriate?BG-05 What constraints govern the placement of roles at particular locations?BG-06 What roles required for business functions require to be within the related business unit and what roles require to be outside of it?Sample Management Questions:BM-02 How should resources be assigned to locations (i.e., relocation/rotation policy)?3. Use Cases and Process Flows describe how processes and services interact withroles as well as with events.Sample Governance Questions:BG-07 What are the most common event triggers and role interactions?BG-08 What exception use cases and process flows are important? 56
  • 56. Sample Management Questions:BM-03 How do we best cater to high volume interactions?BM-04 How do we deal with time-critical events?BM-05 How do we deal with exceptions? 57
  • 57. Application Layer DependenciesThe business layer that we just considered identifies the business intent – the enterprisesvision and mission – and the resulting high-level business functions, their constituentprocesses, and the individual steps (operations) that make up these processes. Butprocesses and steps of processes dont float disembodied in an organisational function“soup”. They are usually grouped by functional domain, and in the Technology Layer, eachgroup is housed in an appropriate “container” under the care of suitable custodians. Tocomplicate matters, the “containers” of these groups of operations have life-cycles anddependencies of their own which demand to be managed.One of the impediments to truly understanding the Application and Information (Data)Layers of an organisation is our tendency to be distracted by how business logic and dataare implemented. In other words, the Technology Layer crowds out the Application andInformation (Data) Layers in our minds. What is known as the “As-Is” architecture of anorganisation also tends to fuse these three important layers into monolithictechnology-based entities, because these are what we can see and touch, so to speak.To be successful in SOA thinking, we need to suspend for a while our awareness of thephysical landscape of hardware and software, i.e., how business logic and business dataare implemented, and step back to first see how they should be organised for the optimalfunctioning of the enterprise. With this understanding, we can then begin to see our “As-Is”landscape with fresh eyes and gain insights into the dependencies that exist at theApplication, Information (Data) and Technology layers.Our focus at the Application and Information (Data) Layers will be on how to organisebusiness logic and business data, respectively. Our focus when we get to the TechnologyLayer will then be on how to implement the logic and data that have been so organised.Funnily enough, looking at the Technology Layer and the way business logic and data areimplemented gives us insights into how they are typically organised at these higher layers.A generic name for a group of related operations housed in a container is “application”, butthis is a relatively abstract term. There are two concrete types of application that weusually need to deal with. They are “products” and “services”.While products and services, being ways to implement business logic, are TechnologyLayer entities, their distinctive approaches to organising business logic begin at theApplication Layer. 58
  • 58. Products are containers that implement pre-defined processes and their constituent stepsor operations, encapsulating them from external view except through native interfaces.Products can be thought of as “black box” applications.Services are containers for groups of operations that are individually exposed to externalsystems (as opposed to being encapsulated and only accessible as part of pre-definedprocesses). Services can be considered “glass box” applications. External process External process Operation Operation Operation Operation Operation Operation Service Product Fig. 23 – In a Service, all constituent operations are individually visible and available to compose into external processes. In a Product, processes are internal, “baked in” and not changeable, and not all operations are externally visible. Some Products may consciously expose a number of their constituent operations to enable new, external processes to be built from them, and these are more “service-oriented”.We saw during our discussion of the business layer that DDDs ubiquitous languagedefines both the high-level data model and high-level process model for all the businessfunctions of the enterprise. The decisions on how operations should “clump” together toform products and services, and how these should then interact with each other toexchange information are the key organising decisions at the Application and Information(Data) Layers.Cohesion and CouplingOur recommended approach to making these organising decisions is to apply thedependency principles of “cohesion” and “coupling”. These terms were first introduced in“Structured Design”, a 1974 paper by WP Stevens, GJ Meyers and LL Constantine. “Cohesion refers to how closely all the routines in a class or all the code in a routine support a central purpose” - Steve McConnell 59
  • 59. In other words, things that “belong” together should go together. When related functions(to use the term loosely) are found together, they are said to be highly cohesive. Highcohesion is a desirable feature, but as we will see, there are different criteria that aresimultaneously possible that could result in how functions are grouped.At the Technology Level, the cohesion of related functions may not be as high as it shouldbe. This is either because products are often purchased off the shelf, and their functionalboundaries do not cleanly mesh together within the organisations ecosystem, or becausein-house built products and services were not architected with a consistent vision offunctional boundaries and data models. The gap between the ideal and the actual is whatneeds to be remediated at the Technology Layer, but any such remediation requires anunderstanding of what belongs together at the Application Layer. Thats why theApplication Layer is so important. A well-designed Application Layer that is used to makedecisions on Technology artifacts is like a system of satellites providing GPS navigation tocars at the street level. Without such guidance, we can get hopelessly lost in the maze andchaos of the corporate IT network.The governance function at the Application Layer deals with identifying the deviations inthe As-Is architecture from an ideal cohesion-based application grouping. Themanagement function at the Application Layer deals with formulating plans to remediatethese deviations, and these plans then translate into appropriate pieces of work at theTechnology Layer.There is a concept related to “cohesion” called “coupling”, which we will look at briefly nowbut cover in detail in the next section. "If two modules communicate, they should exchange as little information as possible" - Bertrand MeyerThe perceptive will note that this is a prescription for minimal Data Layer dependenciesbetween two systems. When that is ensured, the systems are said to have low coupling.As we know from our extensive case studies on dependencies, low coupling is a highlydesirable feature, just like high cohesion, and the two concepts are complementary. Thatswhy the design of the Application Layer and Information (Data) Layer often go together.Design at the Application Layer is guided by the high cohesion principle. Design at theInformation (Data) Layer, especially the design of data exposed between applicationsthrough interfaces, is guided by the low coupling principle. 60
  • 60. This section will mainly focus on application design, and hence will leverage the “highcohesion” principle. The next section will focus on information (data) design, and willtherefore leverage the “low coupling” principle.To internalise the concept of cohesion, lets do a fun exercise. We have a map showing aset of islands in the Pacific Ocean, and theres nothing to distinguish them from each otherat first glance. The objective is to group them into distinct collections such that eachcollection of islands has something in common that sets it apart from the others.Try it yourself first before flipping forward to see some possible answers. 61
  • 61. A Fun Exercise in Applying the High Cohesion Principle Fig. 24 – Group these Pacific islands into appropriate collections!
  • 62. Fig. 25 – An arbitrary, random and whimsical attempt to group these islands with no rigorous basis at all
  • 63. Fig. 26 – A cultural basis for grouping the islands, resulting in groups that are each internally cohesive and distinct from the others.Source: http://en.wikipedia.org/wiki/File:Pacific_Culture_Areas.jpg
  • 64. Fig. 27 – A possible geopolitical basis for grouping islands (circa 2030?). Such a classification could coexist with the cultural one.
  • 65. The key takeaway from this exercise is that the criteria for cohesion are critically importantin determining the groups that subsequently emerge. If we apply a cultural criterion, thenwe end up with the Polynesian, Melanesian and Micronesian island groups. If we apply ahypothetical geopolitical criterion, we end up with spheres of influence of Pacific powers.Criteria for High CohesionReturning to SOA and to the point where the business layer leaves off, a key question iswhat criteria must be used to evaluate the natural cohesion of operations.There are at least two ways in which operations can be grouped, but before we discusswhat these are, lets look at an analogous example to ease our understanding.A matrix organisation groups people in two different ways at the same time. The functionalor “straight line” reporting groups define their job roles, and this is one criterion forcohesion. But on projects, multi-disciplinary teams need to be put together, with one or afew individuals from each of these functional groups. Project teams are united for a periodof time in their pursuit of a common goal, and team members have “dotted lines” reportingto the project owner until the project completes, the team is disbanded and members arereassigned to other projects. Hence project goal is a second criterion for cohesion. Goal-oriented Functional group team Project Mgrs Architects Developers Testers Project 1 Person Person Person Person Project 2 Person Person Person Person Project 3 Person Person Person Person Project 4 Person Person Person Person Fig. 28 – A matrix organisation groups people simultaneously in two different ways 66
  • 66. In very similar fashion, the atomic “operations” that are the functional units of a businesscan be put together in at least two ways. The business layer has already applied agoal-oriented cohesion criterion to group operations into processes. But another criterionfor cohesion is the “domain”, or subject area, to which the operations pertain. Groupingoperations according to a domain-oriented cohesion criterion creates “applications”. Thedetermination of the “right” domains for a business is by no means always obvious. Does a“handle customer payment” operation belong to the “Customer” domain or to the“Payment” domain? Either classification may work. As we saw with the islands example,the decision on what the right criteria (i.e., domains) are is a crucial governance questionat the application layer.So to recapitulate, when operations are grouped together by goal, they form Processes.When operations are grouped together by “domain”, they form Applications. Applicationsthat hide the way operations are put together internally are called Products. Applicationsthat expose individual operations are called Services. And this tells us the true place of theService concept within Service-Oriented Architecture, - a static way to group externallyexposed operations based on their functional domain. Application (Product or Service) Process Customer Product XYZ PQR Domain Domain Domain Domain Business Operation Operation Operation Operation Process 1 Business Operation Operation Operation Operation Process 2 Business Operation Operation Operation Operation Process 3 Business Operation Operation Operation Operation Process 4 Fig. 29 – Operations can also be grouped simultaneously in two different ways 67
  • 67. Process, Product and ServiceHeres a more detailed diagram that shows a Process, a Product and a Service togetherwith their related components. We also get a sneak preview into elements of theInformation (Data) Layer because business logic and business data cannot be isolated. Service (“Glass box” Application) Process chain/nest orchestrate Public manipulate Public Internal Data Process Step Process Model (Operation) expose conform to externally Interface Data conform to Domain Data Model Dictionary proxy, aggregate loosely Native User Internal Data conform to Interface Model expose expose internally manipulate externally Internal Internal Process orchestrate Process Step (Operation) Product (“Black box” Application) nest Fig. 30 – Process, Product, Service and related EntitiesIn all cases, there is an internal data model that is manipulated by operations. Whenoperations form part of Services, they can be accessed from external systems, and as partof this interaction, data is exchanged between the external systems and the operations.This is the interface data model. Both the interface data model and the internal data modeltend to conform to the same “data dictionary”, that of the domain to which the operations 68
  • 68. belong, but there is no tight relationship between them. We will see why when we studythe Information (Data) Layer in greater detail.In contrast, when operations form part of Products (as is the case with off-the-shelfsoftware packages), many business processes come pre-built as part of the productsfunctionality. The internal data model may not strictly conform to any domain datadictionary that the procuring enterprise recognises. Also, since the operations within theProduct may not be accessible individually from the outside, there may only be somevisual means of interacting with external parties, and there is no formal interface datamodel to speak of. Some products may expose a subset of their operations to externalsystems the way Services do, so this is a hybrid model between Service and Product.In other words, the main difference between a Product and a Service is in the extent ofvisibility and composability of its constituent operations.The “internal data model” and the “interface data model”, as well as their relationship to adomain-specific “data dictionary”, are topics that we will cover in the next section on theData Layer.With this lengthy conceptual introduction, it is time to look at the fundamentaldependencies that exist at the Application Layer. 69
  • 69. Application Layer Dependency Check-listsThe application layer dependencies as derived from TOGAF are illustrated below. Notethat the TOGAF model of the application layer includes physical application components,i.e., the implementation of business logic or what is properly the Technology Layer. Functional Model Actor Role Organisational ownership, logical ownership, Unit usage interaction usage usage Logical App Component Business responsibility (Product or Function (functional domains) Service) realisation Gaps and overlaps, migration plan Physical App Component (Software Process realisation Implementation) distribution physical communication, decomposition Process Step manageability (Operation) Location Application Portfolio (strictly speaking a Technology Layer Dependency Group) Fig. 31 – Dependencies and Dependency Groups at the Application Layer (TOGAF)There are two broad Dependency Groups that are apparent at the application layer.1. The Functional Model picks up the business footprint model from the business layerand applies domain cohesion to determine which business functions belong together as 70
  • 70. logical application components (products and services). It then defines the ownership andusage relationship of these logical application components to actors/roles as well as toorganisational units. Logical application components may also interact and havedependencies on one another.Sample Governance Questions:AG-01 What criteria must be used to evaluate the natural cohesion of operations (i.e., responsibility for business functions)?AG-02 (Hence) What are the appropriate functional domains into which the enterprises process steps (operations) should be classified?AG-03 What is the right mapping that should exist between business functions, logical applications (products/services) and implementations? What is the mapping that currently exists?AG-04 What other dependencies govern applications (other than domain-based cohesion)?AG-05 What interaction models are appropriate between applications? (Real-time, asynchronous, batch, etc., also invocation versus event-based mechanisms)AG-06 What are the operations that need to be exposed (through services) to enable processes to be composed from them?AG-07 What are the dependencies that exist between the applications we have defined? (These should be minimal, and expressible in terms of exposed operations (services) alone.)Sample Management Questions:AM-01 How can we ensure optimal coverage of the required business functions using our applications (products and services)? (Future state Application Layer architecture)AM-02 How best can we procure, develop, test, deploy and maintain our products and services? (Roadmap)2. The Application Portfolio shows the “physical” implementations of products andsystems that exist (or should exist) in the enterprise. As mentioned, this is strictly speaking 71
  • 71. a Technology Layer Dependency Group, but it may make logistical sense to have thesame governance and management committees look at both the logical cohesion ofbusiness operations as well as their ultimate physical implementation. Physical applicationcomponents are a realisation of their logical counterparts and execute processes and theirconstituent steps. Physical application components are distributed geographically amongvarious locations and are used by various actors and roles.Sample Governance Questions:AG-08 What product implementations exist in our environment? What is missing or superfluous (gaps and overlaps)?AG-09 What service implementations exist in our environment? What is missing or superfluous (gaps and overlaps)?AG-10 What is our policy around new functionality – buy or build? (The answer comes from the enterprise dependency governance committee.)Sample Management Questions:AM-03 How do we migrate from the current implementation landscape to the target state?We now understand that operations can be grouped in at least two different ways (i.e., bygoal and by domain) to form Processes and Applications, respectively, and that the twodomain-based groupings (Product and Service) pertain to encapsulated groups ofoperations and to externally visible operations, respectively.Both Products and Services manipulate data conforming to an internal data model.Services additionally expose an external data model through its operations. The externaland internal data models are loosely correlated, and a domain-specific “data dictionary”may be postulated to provide a common foundation to all Products and Service operationswithin a domain.We are now ready to move down to the Information (Data) Layer and study the relatedconcepts of “Data on the Inside” and “Data on the Outside”. 72
  • 72. Information (Data) Layer Dependencies Over the last two sections, we have analysed not only the business intent and all the processes and operations that arise as a consequence, but also the set of dependencies characterised as cohesion that suggested how best to clump operations into “applications”. We now need to understand how these applications will interact, specifically how they will exchange information. And this brings us to the dependency principle called coupling: “If two modules communicate, they should exchange as little information as possible” - Bertrand Meyer At the outset, let us point out that while TOGAF goes into a fair amount of detail at the Information (Data) layer to analyse entities and their relationships, it does not distinguish between “Data on the Outside” and “Data on the Inside” 18. This distinction, made most eloquently by Pat Helland in his seminal paper 19, is crucial from a coupling perspective. Data on the Outside versus Data on the Inside Applications develop dependencies on the data that they can “see”. “Data on the Inside” is well encapsulated inside an application and the applications own dependency on it has limited impact, because a change to an applications internal data does not impact other applications. In contrast, “Data on the Outside” always has a dependency implication, because it is shared or exchanged between applications, all of which then develop a dependency on it. In other words, a change to shared data impacts more than one application. Since our approach is dependency-focused, we need to split TOGAFs generic “Data Entity” into internal and external flavours and deal with them separately. Interface Internal Data Data Model Internal Data Model (A) Operation a1 Operation b1 Model (B) Application (Service/Product) A Application (Service/Product) BFig. 32 – The Internal Data Model of each application corresponds to “Data on the Inside”, and the Interface Data Model that they share corresponds to “Data on the Outside”. 18 Another fallout of TOGAFs view of SOA as a subset of technology and not as a pervasive organising principle. 19 “Data on the Outside vs. Data on the Inside”, Pat Helland (http://bit.ly/RHj7dp) 73
  • 73. Aspects of Low CouplingThere are two levels of dependency that we must concern ourselves with at theInformation (Data) Layer. One is the dependency that applications develop on each other,or more correctly, the dependency they develop on their shared interface data model. Theother is the dependency between any given applications internal data model and aninterface data model that it shares with other applications. Dependency between applications 1 through their Interface Data Model 2 2Dependency between an applications Internal Dependency between an applications Internal Data Model and its Interface Data Model Data Model and its Interface Data Model Interface Internal Data Data Model Internal Data Model (A) Operation a1 Operation b1 Model (B) Application (Service/Product) A Application (Service/Product) B Fig. 33 – Two levels of dependency at the Information (Data) LayerIts very important to recognise that the dependency of an application on any data that it“sees” can be quite significant, with negative impacts to agility, cost and risk. So ourstrategies to reduce dependency should be as follows: 1. To reduce the dependency of an application on an interface data model, we follow a minimalist strategy. In other words, if an operation needs two data elements in order to do its job, then we need to ensure that no more than those two data elements are in the interface data model. The smaller the “radar cross-section” of an operation, the better. 2. To reduce the dependency of an applications internal data model on its interface data model and vice-versa, we employ a mediating strategy. In other words, we make both these models rely on a third model rather than on each other. This point is worth emphasising because too many system designs assume that the internal data model and the interface data model are one and the same! One can imagine the kinds of dependencies that this assumption can lead to. 74
  • 74. Dependency between Application As Internal Data Model and its Interface Data Model is total, because they are one and the same! Consequently, dependency between Application B and Application A is extremely high, and the integration between them is brittle Internal Data Internal Data Model (A) Internal Data Model (A) Operation a1 Operation b1 Model (B) Application (Service/Product) A Application (Service/Product) B Fig. 34 – What if an applications internal and interface data models are the same?A good way to recognise when this is happening is to ask ourselves if external systems arelikely to be impacted when an applications internal data model changes. If they are, then itmeans the applications internal data model is tightly coupled to its interface data modeland the link needs to be broken. We need to introduce a mediating entity.The mediating entity for “Data on the Inside” and “Data on the Outside” is a common “datadictionary”, so the two arent entirely unrelated. Thats why we dont say the two modelsare decoupled, but merely loosely-coupled. The data dictionary is their only link.The Domain-specific Data DictionaryEvery domain has a data dictionary, i.e., a model that describes the data of that domain ina comprehensive, consistent and definitive way. The loose coupling between a domainsinternal data model and its interface data model stems from the fact that both of these arebased on the same data dictionary and share some data structures, but nothing more 20.20 This approach is an application of the Venetian Blind pattern (http://bit.ly/UXFqL2), with types defined in the data dictionary and elements defined in the internal and interface data models. 75
  • 75. Fig. 35 – The data dictionary for a domain (type hierarchy and composition)A data dictionary defines types. There are two fundamental types – entities and valueobjects21. Entities are persistent and have identifiers. Value objects are anonymous. Theyhave structure but no identity. They are only persisted when they form part of an entity.A data dictionary is restricted to defining only type hierarchies and compositionrelationships. The reasons for this will become clearer when we look at how the datadictionary is used by an applications internal data model and its interface data model.[In terms of the Technology Layer implementation of the data dictionary, this may just be ahuman-readable document that is used to guide the design of the other two data models. Itcould also take the form of an XML schema document with type definitions,]The Internal Data Model (“Data on the Inside”)The internal data model for an application leverages its domain-specific data dictionaryand models the various relationships between entities. Some specialised inheritancerelationships peculiar to the application may also be modelled.[In terms of its Technology Layer implementation, the internal data model could beobject-oriented or relational (the most common), but its elements should conform to thedomain data dictionary.]21 As follows from the Domain-Driven Design approach. 76
  • 76. Fig. 36 – Internal Data Model (entity association, aggregation and instantiation)The internal data model of an application is the one that defines how entities hang togetherand what their relationships are. “Black box” applications (Products) work on an internaldata model that may or may not relate to a domains data dictionary, because they couldvery likely be off-the-shelf software packages that come with their own view of the domain.However, “glass box” applications (Services) built in-house by an organisation wouldbenefit from using an agreed data dictionary for the domain when they manipulate data.The Interface Data Model (“Data on the Outside”)The interface data model is a different beast altogether from the internal data model. It isnot a “model” of a system in the same way that the internal data model is. It is just a loosecollection of data elements that needs to form part of a message passed betweenapplications. To use an analogy from C++, the internal data model is like a set of classes;the interface data model is like a set of structs. An important constraint to keep in mind isthat interfaces need to balance the reality of change with the need for stability. We willelaborate on this shortly.Another important point to remember is that the name of an operation is part of itsinterface data model, because a change of name is immediately visible to other systems.[At the Technology Layer, the interface data model tends to be implemented either as anXML schema or JSON schema document.] 77
  • 77. Fig. 37 – Interface Data Model (type aggregation)Importantly, the interface data model must not contain entity types, even though many ofthe attributes of entities may be found within a message. This is because it needs to bemade crystal clear that what is being passed between applications is not a reference to a“live” entity instance but merely an immutable representation of it. Any identifier thataccompanies the entity representation should be a specially-created “external identifier”and not the internal identifier of the entity within the application. Applications should usethe mapping between external and internal entity identifiers to determine which entityinstance a given representation pertains to. This association of identifiers is a key aspectof loose coupling at the Data Layer, because any visibility of internal identifiers externallycreates a dependency that should not exist.The interface data model defines messages that flow between applications whenoperations are invoked, so the main element is a message type. Various types ofmessages can be defined, and each of these is defined as an aggregation of other valuetypes. Why is the value type a super-type rather than a sub-type? The dictionary definesboth super-types and sub-types, doesnt it? Wouldnt a sub-type be a better fit? Lets see.Message Data “on the wire”Consider the data that applications actually exchange “over the wire” when they interact.For this, we need to skip ahead for a while to the Technology Layer to look at animplementation, e.g., an XML document. An XML document is expected to conform to anXML schema that describes it., but how well (i.e., how tightly) should the schema describethe document? 78
  • 78. Lets postulate a message data model that precisely describes a message, e.g., an XMLschema that is highly tailored to the XML document that goes over the wire. What is thedifference between this message data model and the interface data model? Shouldnt theybe exactly the same?The answer is no, and the reason relates to the point we made earlier - interfaces need tobalance the reality of change with the need for stability. There is a crucial element tomessage design that leverages the data dictionary to provide a sufficiently low level ofcoupling between applications, but not too low.The message data model for any message document exchanged between applicationsshould look like this. Fig. 38 – Message Data Model (instantiation of value subtypes) 79
  • 79. The interface data model is shown circled in red, and there are one or more levels ofsubtypes between the interface data model and the actual (instance) elements of themessage document.Recall that the data dictionary defines the type hierarchy (supertypes and subtypes) for allthe data elements in the domain but does not define the elements themselves. Thisapproach allows the binding of types to message elements to be deferred to as late astage as possible.One may expect the message data model to define the interface, since this exactlyvalidates a message document. But there are two drawbacks in doing this.1. Specialised subtypes, while providing tighter definition, are more sensitive to change.The degree of dependency between applications is higher. Any change to a subtype willnecessitate a change to the interface data model and impact other applications. Having tosupport multiple concurrent versions of an interface data model is then an unavoidableconsequence of two simultaneous requirements – for change and for stability.2. Besides, any two minor variants of a similar interface data model will require twodistinct definitions, even if they share common super-types.In other words, high levels of version churn and proliferation of services are the naturalconsequence of tight coupling to an overly detailed interface definition. This might soundfamiliar to large “SOA shops”!We can balance the need for change with the need for stability by defining interfaces interms of super-types. This gives us the ability to describe an interaction meaningfully butalso withstand minor changes to the data that is exchanged, which is why the interfacedata model shown earlier used super-types for values rather than specialised subtypes.The message document therefore conforms to the interface data model without beingtightly bound to any one specialised interface.With this conceptual framework as a background to help make sense of the Information(Data) Layer, let us now turn to look at the dependencies that exist here, and derive somegovernance and management check-lists from our analysis. 80
  • 80. Information (Data) Layer Dependency Check-listsThe core TOGAF-derived Information (Data) Layer dependencies are illustrated below,with our refinement of the data model into internal and external data entities linked to ashared data dictionary. Internal Data Dependencies Entity-Relationship Models; Class Hierarchies; Data Structures, Life-cycles and Events; Master-Replica Relationships; Business Value of Data; Security Classification, etc. Internal conformance Data Dictionary Data Entity Element conformance physical logical data model data model exposed data Physical App Logical App Interface Component Component Data Entity consumed data responsibility (functional domains) External Data Dependencies mission Organisational Business inputs and Unit Function outputs realisation coordination Process Step Process (Operation) Data Ownership and DisseminationFig. 39 – Dependencies and Dependency Groups at the Information (Data) Layer (TOGAF) 81
  • 81. Three Dependency Groups can be seen at the information (data) layer.1. Internal Data Dependencies are perhaps less important in the larger scheme of things.The diagram lists the various types of dependencies that should be analysed.Sample Governance Questions:IG-01 What is the minimal data dictionary for each functional domain, as suggested by the various internal data models of applications in that domain?IG-02 What is the life-cycle of data items? What core events impact these life-cycles?IG-03 What data items are mastered and where? What data items are replicated and where?IG-04 What metadata applies to data items (business value, security classification, etc.)?Sample Management Questions:IM-01 How do we remediate the internal data models of applications to conform to the domains data dictionary? (In many cases, remediation is neither feasible nor necessary. It may suffice to document the logical mapping between these models along with exceptions and inconsistencies to aid in maintenance and functional enhancement.)IM-02 How do we ensure that data is kept current and relevant?IM-03 How do we implement Master Data Management (MDM)?IM-04 How do we leverage metadata when managing data?2. External Data Dependencies are more critical. “Interface data entities” are looselyassociated with “internal data entities” through the application components that realiseservices. Interface data entities are exposed as inputs and outputs of operations. 82
  • 82. Sample Governance Questions:IG-05 What (minimal) data dependencies should exist between groups of functional capabilities? (This is probably one of the most important SOA questions of all, in spite of its innocuous appearance, and therefore the one on which the Information (Data) Governance Committee should spend a disproportionate amount of time.)IG-06 What is the minimal data dictionary for each functional domain, as suggested by the various interface data models of applications in that domain?IG-07 What are the appropriate data structures underlying interface data? (e.g., type hierarchies for data exposed through service interfaces)IG-08 What is our version support policy when dealing with changes to interface data models?Sample Management Questions:IM-05 How do we remediate the interface data models of applications to conform to the domains data dictionary?IM-06 How do we communicate the interface data model of an application to others? How do we communicate changes to it?IM-07 How do we deal with changes to the data dictionary that impact the interface data models of applications? How do we deal with changes to the interface data models of applications that necessitate changes to the data dictionary?IM-08 How do we format data?IM-09 How do we perform data validations (e.g., coarse-grained schema validation against base types, fine-grained validation within implementations)?3. Data Ownership and Dissemination traces how data entities are related toorganisational units and processes through business functions and applicationcomponents.Sample Governance Questions:IG-09 What business unit and business function owns a domains data dictionary? 83
  • 83. IG-10 What business unit and business function is responsible for initiating and managing changes to the data dictionary?Sample Management Questions:IM-10 How do owners of a domains data dictionary interact with other stakeholders?IM-11 How are change requests communicated to the owners of a domains data dictionary? How are changes communicated back to all stakeholders?IM-12 How are the semantics of a domains data dictionary explained to owners of other domains? (This is crucial when brokering or transforming messages.) 84
  • 84. Technology Layer Dependencies It has been a long road to finally arrive at what the impatient would consider to be the only SOA layer that really matters – the Technology Layer! But hopefully, our discussions in the previous sections have illustrated the importance of the higher layers of the enterprise. Technology is of course important, because business logic is only useful when it is implemented, but technology has its place in the overall scheme of things. We need to determine how business logic and business data are logically organised before we can start to make decisions on how they must be housed and/or implemented. The following diagram shows how the business logic and data dictated by the enterprise vision and mission are organised. Note that while Products are largely “black box” applications that hide all data, operations and processes behind a native interface, the more “service-oriented” among them could also expose some operations and related interface data to be consumed and orchestrated by external processes. Services, on the other hand, do not hide but explicitly make operations visible to external processes to orchestrate, and (ideally) make a clear distinction between “Data on the Outside” (interface data) and “Data on the Inside” (internal data). Native Interface Internal Process External Process Interface Data Interface Data Interface Data Usually Notthe same Operation(s) Operation(s) the same Internal Data Internal Data Product Service Two types of Application Fig. 40 – Business logic and data organised into applications and ready for implementation 85
  • 85. Implementing ProductsImplementing “black box” applications is relatively easy, and organisations have beendoing this for decades. Indeed, this is the traditional way that organisations haveimplemented business logic. The only decisions here have been “buy or build?”.In recent times, there has been a push from consumers of applications to have more of thebusiness logic inside a Product exposed so that it can participate in business processesdefined externally. Thats why many products today feature “service APIs”. Obviously, evenwith a service interface, a products operations cannot readily be “consumed” because theinterface data model of those operations is not likely to conform to the organisationsdomain data dictionary, and considerable effort is often required to bring these in line withthe other operations of the enterprise.Products, being monolithic and standalone applications, are boring. Worse, theyre out ofstyle in our collaborative world! The more interesting aspect of our discussion, therefore, ishow to implement Services. With an application landscape composed mainly of Services,the implementation of business logic should become like the assembly of Lego TM blocks.Implementing ServicesThis is what were interested in doing: Process A process orchestrates multiple operationsHence this is what we want to see: Interface Data A service exposes one or Service more operationsBut this is often what we have: Native Interface Legacy systems expose non-standard interfaces Product 86
  • 86. Our challenge is therefore around building new Services and converting Products to makethem look like Services, so that they can all be composed into Processes that implementthe business functions of the organisation and help it achieve its mission and vision.Implementing the Nouns and Verbs of the Interface Data ModelAn operation can be loosely described as some actor performing some action on someresource, using some contextual data. The Interface Data Model is the completedescription of how the operation is invoked by the actor.At the Technology (with a capital T) Layer, this relatively abstract description needs to betranslated into a working implementation. The exact flavour that this implementation takeswill depend upon the technology (with a small t). The two common technologies used tobuild Services are SOAP-based Web Services22 and REST.When working with the SOAP approach, the verb (the action being performed) and one ofthe nouns (the resource being manipulated) are usually merged into the name of theoperation (e.g., “getCustomerDetails”). The associated data that is passed and returned isencoded in XML documents (which conform to the Interface Data Model in terms ofsupertypes, as we saw earlier).When working with REST, the resource needs to be identified with a suitable URI (e.g.,“/customers/{id}”) and the verb is a standard one (i.e., “GET”). Associated data is passed inthe body of the HTTP request and response.Regardless of the flavour of technology chosen, there are some standard ways toapproach the implementation exercise. The thrust of this approach is to be able to treat allApplications as Services (even “black box” ones), and to be able to consume theiroperations by orchestrating them within Processes.22 Be aware that technologies introduce fresh dependencies of their own in the course of implementing a set of operations. In the SOAP world, WSDL is a prime culprit. The dependencies that a WSDL file has on service and operation definitions, and the dependencies of these, in turn, on input and output (XML) schema files is the cause of much brittleness. A minor change to a single element of a schema file pertaining to a single operation can ripple through and change the version of a WSDL file, impacting many otherwise unrelated operations, services and client systems. REST introduces far fewer dependencies of its own, with the binding to HTTP being the major one. 87
  • 87. The Three Core SOA Technology ComponentsIn a nutshell, there are just three core technology components that we need to learn about,which will help us in our quest to turn all the applications in the enterprise into Lego TMblocks and compose them into processes. They are the Service Container, the Broker andthe Process Coordinator.Service Container: When business logic does not already exist and is not available off theshelf, it has to be developed in-house and must be hosted in a way that makes it easy forother applications and systems to invoke its functionality. That calls for a ServiceContainer.We depict a Service Container visually as follows: Fig. 41 – Notation for a Service ContainerHow do we use a Service Container? Heres how. Service Custom logic Consumer Service interface Service ContainerFig. 42 – Hosting business logic in a Service Container and exposing it through a “service interface”The figure above shows that custom functionality, when hosted within a Service Container,is exposed as a potentially reusable service to other components in the system.Service Containers in practice may be simple web servers exposing SOAP or RESTinterfaces. 88
  • 88. Broker: The Service Container is a useful component when we need to host a particularpiece of functionality that we had to develop ourselves. In practice, we do not generallydevelop complete, end-to-end solutions from the ground up. The solution we put togetherwill usually be able to exploit pieces of logic or data that already exist somewhere in theorganisation, within some legacy system or application, i.e., a Product. We will invariablycome up against some complications that prevent us from readily accessing and usingsuch components.• Perhaps the legacy component that hosts our required logic speaks a specialised or proprietary protocol. To use an electrical analogy, we need an adapter to let us plug into this differently-shaped socket. An adapter can translate proprietary protocols into more open ones.• Perhaps the data that this legacy component provides is not in exactly the right format that we can readily use. Again, to use an electrical analogy, we need a transformer to step its voltage up or down. Transformers can enrich data and massage it into a form that is more readily understood and usable. Usually, that means an Interface Data Model that conforms to a domains Data Dictionary.• And perhaps there are reasons why we do not want our solution to directly access this legacy functional component. We may want to hide, proxy or throttle access to it. An extension block or power board lets electrical components tap into power without directly accessing a wall socket. In the SOA context, we call such a component a mediator.There is something in common between the functions of an adapter, a transformer and amediator, and a single component can usually perform all three functions at once. We callthis combined component a Broker, and depict it visually as follows. Fig. 43 – Notation for a BrokerIn practice, the role of a Broker is performed by an Enterprise Service Bus in the case ofSOAP-based web services. REST services can usually adapt to different kinds of serviceconsumers through content negotiation and thereby act as their own Brokers. In caseexternal Broker components are required for REST services, these are usually web proxy 89
  • 89. servers.This is how we use a Broker. “Transformer” Proprietary Service interface logic Legacy Service “Adapter” interface (“Mediator” function) component Consumer logic Broker Fig. 44 – Mediating access to a legacy “black box” component with a Broker, adapting its native interface and transforming data to create a more standardised interface data model 90
  • 90. Process Coordinator: LegoTM blocks are great for building solutions quickly, and a Brokercan even tie together services in a rudimentary way, but sometimes we dont know theexact steps of the logic in advance. When we need to pull components togetherdynamically, based on a status that can only be evaluated at run-time, we need a ProcessCoordinator. This is how we visually depict a Process Coordinator. Fig. 45 – Notation for a Process CoordinatorHeres how a Process Coordinator is used. Operations Service Process logic (Process steps) Service interface Consumer for the process Process Coordinator Fig. 46 – Using a Process Coordinator to pull individual operations into a step-by-step process that implements a business functionIn a SOAP environment, Process Coordinators are BPEL engines. The REST processmodel relies on choreography, not orchestration, hence may not need this component. 91
  • 91. We can readily imagine situations requiring a combination of these three component types. Operations Legacy (Process steps) Broker component Service Service interface Consumer for the process Process Coordinator Service ContainerFig. 47 – A Process Coordinator orchestrates two operations, one of which is directly hosted within a Service Container and the other is actually implemented within a legacy “black box” application but made to appear like a standard operation through the use of a Broker
  • 92. How Not to Use a BrokerThe right tool for the job: Brokers are very powerful, but they must not be used in placeof a Service Container or a Process Coordinator. Such incorrect use of a Broker outside ofits normal role as a mediator introduces fresh dependencies with impacts to stability andperformance23. Designers and developers should be equally proficient in the use of allthree core SOA components to avoid the temptation of “hacking” the Broker to performfunctions it is not meant to do.Not a hub-and-spokes solution: Perhaps because of the prohibitive cost of manycommercially available Brokers, there is a tendency to install just one instance of thiscomponent for the entire organisation and push all traffic through it 24. The obviousimplications of such a centralised, hub-and-spokes architecture relate to performance (i.e.,scalability of throughput) and to availability (because of its emergence as a single point offailure).However, the Broker is inherently federated! Its mediation, transformation and adapterfunctions are best performed closest to the endpoints where functionality is either exposedor consumed. This decentralised or “federated” architecture is illustrated below. Service Container Service Container Legacy Process Broker Service Coordinator Provider Broker Broker Legacy Legacy Service Service Consumer ProviderFig. 48 – The Broker Deployment Architecture – Naturally Federated, not Hub-and Spokes23 This is commonly referred to as ESB-itis.24 This is another common symptom of ESB-itis. 93
  • 93. Implementing the Adverbs of an OperationWe may seem to have glossed over some important aspects of implementing businesslogic, and these pertain to what are known as “non-functional” requirements. In otherwords, “how” something is done is as important as “what” is done. Our functionaldefinitions of processes and operations deal exclusively with the “what”, but the “how”aspect isnt often stated as explicitly. Nevertheless, we need to deal with these “adverbs” inour implementation just as we do with the “nouns” and “verbs”.Heres a quick overview of some of the more important ones. They will feature in thedependency check-lists at the end of this section.Asynchronous interaction:SOAP-based Web Services are based on the notion of messaging, and it is important notto be trapped into the older and deprecated RPC style. Asynchronous capability is inherentin the SOAP model.REST appears to be intractably synchronous because of HTTPs blocking model ofclient/server interaction. However, this is only true of the “transport” side of HTTP. On thelogical “message” side, asynchronous messaging is relatively easy to model using thestatus code “202 Accepted”, which is an acknowledgement rather than a response. Theresponse can be returned at a later time either through polling or a callback mechanismset up at the time of the original request.Security:There are many aspects to security, such as confidentiality (message encryption), trust(authentication of the source), authorisation (access control), etc.SOAP uses special headers to ensure all of these, and there are standards such asWS-Trust, WS-SecureConversation and WS-Security to provide a measure of securityaround interactions. It is also possible to specify security requirements declaratively usingWS-SecurityPolicy.RESTs security model for confidentiality is relatively clunky (TLS/SSL), in that it is notroutable or capable of partially encrypting message payloads, but it is simple. Forauthentication and authorisation, the newer web-based security standards such as OpenIDConnect and OAuth 2.0 are elegant mechanisms that can be layered over the actualservices themselves in an unobtrusive way. 94
  • 94. Reliable Delivery:SOAP follows the TCP model of reliability in its WS-ReliableMessaging protocol. Themechanism of message identifiers, acknowledgements, timeouts and retries is exactlyanalogous to TCPs sliding window protocol.REST-based systems often adopt a different model of reliability based on idempotence.The REST verbs (with the exception of POST) are all idempotent, which means they canbe retried without danger of (repeated) side-effects. Even POST can be made idempotentif a one-time string is sent along with a request and the server checks for a duplicatebefore acting on the message.Availability:Services are meant to be stateless, and data is either transient (part of the message) orpersistent, never session-based. This allows for redundant servers to be used to hostservices, and this model works for both SOAP and REST. A load-balancer in front of theseservers can ensure availability of the service as well as performance.Processes are a different kettle of fish. They are stateful by definition, and a WS-BPELprocess server in the SOAP world needs special measures to ensure availability. Thereare many “session clustering” or “memory grid” style products to provide a measure ofavailability to a cluster of process servers.Performance:Latency and throughput are common measures of performance. Improvement of latencyrequires detailed analysis and tuning that are specific to the nature of the operation, data,network characteristics, etc. Throughput is relatively more standard in terms of availablemechanisms. Load-balancing a farm of servers hosting operations is a fairly standard wayto scale performance horizontally. Both SOAP and REST can exploit such mechanisms.To improve the performance of process servers, it may be required to host high-overheadprocesses on their own dedicated nodes. 95
  • 95. The fundamental technology layer dependencies to be understood are illustrated below. Technology Portfolio Internal Data Logical App Element Component implementation Technology Distribution Physical App deployment Physical Component Location constraints Technology Dependencies Fig. 49 – Dependencies and Dependency Groups at the Technology Layer (TOGAF)Technology Layer Dependency Check-lists1. The Technology Portfolio traces how logical application components such asprocesses, applications and operations and logical data elements such as elements of theinternal data model are ultimately implemented in technology through physical applicationcomponents. This can be used for a gap analysis of target state and current state.Sample Governance Questions:TG-01 What data elements are co-located with applications in a way that does not permit logical separation?TG-02 What non-functional dependencies impact the deployment of applications on physical servers? (scalability, fault-tolerance, etc.)TG-03 What technologies are best suited to implement various kinds of business logic and data (e.g., rules engines for rules, graph databases for highly complex and arbitrary relationships, etc.)TG-04 Who can access business logic as implemented? (Identity and Access Management) 96
  • 96. Sample Management Questions:TM-01 How do we implement platform capabilities (specific products and technologies)?TM-02 How do we decommission redundant or obsolete platforms?2. Technology Distribution shows how various technologies are deployed at differentlocations.Sample Governance Questions:TG-05 What is the level of location-dependency of every physical application component? (Can everything be moved to the cloud?)TG-06 What is the level of location-dependency of every element of internal data? (e.g., Legislative concerns over moving customer data offshore, etc.)TG-07 What is the optimal number of installations of each physical application component, versus the number we actually have? (licensing considerations)Sample Management Questions:TM-03 How do we optimally distribute applications to where they are needed?TM-04 How do we consolidate and migrate applications to the cloud?TM-05 How do we track all of the technology artifacts that are deployed? (Registries, respositories, etc.)3. Technology Dependencies enumerate the various dependencies that exist betweentechnology components themselves.Sample Governance Questions:TG-08 What dependencies should we legitimately have on platform capabilities, versus actuals? (Storage capacity, latency, bandwidth, availability, scalability, etc.)TG-09 What market-related dependencies do technology components impose on us? (Single dominant vendor, vendor without staying power, etc.)TG-10 What technology platforms afford us the most flexibility and choice? 97
  • 97. Sample Management Questions:TM-06 How do we diversify our sources while keeping the number of platforms manageably low?TM-07 How do we protect data against physical corruption, accidental loss and data leakage?TM-08 How do we monitor the performance and other real-time characteristics of our technology deployment? (Business Activity Monitoring, etc.) 98
  • 98. Bringing about Desired Behaviour – Velvet Glove or Iron Hand?Making sure were doing the right thing (governance) and making sure we do things right(management) both pertain to bringing about desired behaviour.In general, there are two ways to bring about desired behaviour, one obtrusive and theother unobtrusive. The unobtrusive way is often better. The fable of how the sunsucceeded in getting a man to remove his coat where the wind failed, and the saying “Youcan catch more flies with honey than with vinegar” are about this very idea.Consider a door that must be pushed, not pulled, to open. We have often seen examplesof such doors with big bold “PUSH” signs on them. But we also know that lots of peopleunthinkingly try and pull them by mistake anyway. Wouldnt it be far better to design a doorso that it would be physically impossible to pull? This is indeed part of the thinking behindergonomic design. We can now see doors that have no handles but only metal plates that“call out” to an approaching person to push, not pull. These are called "affordances". Withan intuitive affordance, there is no need for a sign telling people to "PUSH". It is physicallyimpossible for a person to do anything but.Another example is from the requirement to control speeding on the roads. There is anobtrusive way to control speeding, which is by putting up clearly visible speed limit signsand enforcing compliance with those limits. Such enforcement may be by installing speedcameras and/or conducting periodic targetted campaigns with mobile police squadsequipped with radar guns.There is however another way to control speeding that may be more effective. Clearlyvisible speed humps force motorists to slow down, because the price of non-compliance isa very uncomfortable ride and possibly a large repair bill from a mechanic. There is noneed for elaborate monitoring and policing, and the expected behaviour is ensuredanyway.We could call these contrasting approaches the “iron hand” and the “velvet glove”.We are fans of the more unobtrusive “velvet glove” approach because we consider “ironhand” style policing to be clunky, expensive and error-prone. However, we recognise thatthe latter approach will sometimes be necessary. Our preferred approach to SOAGovernance and Management is therefore “Unobtrusive and intrinsic wherever possible;obtrusive and extrinsic wherever necessary”. 99
  • 99. Example: Speed limits and policing versus speed humps Enforcing desired behaviour Ensuring desired behaviour (External to design, requires active policing) (Inherent in design, no policing required) Fig. 50 – The Iron Hand and the Velvet Glove of speed reductionHowever, the design of systems that are unobtrusive is orthogonal to our discussion ofSOA governance and SOA management. An organisation would certainly benefit bydeveloping “velvet glove” mechanisms for governance and management, wherebyeveryone in the organisation is almost unconsciously shepherded into following the correctand expected behaviour, but this is an advanced idea that we will not cover further in thisdocument.Its certainly worth considering when an organisation designs its systems, though. 100
  • 100. Summary and ConclusionsService-Oriented Architecture (SOA) should really be thought of as Dependency-OrientedThinking, since vitally important dependencies exist at every layer of the enterprise, andthese have significant impact on an organisations agility, cost and risk profiles.Determining “what” dependencies are legitimate, and “how” these dependencies must bemanaged, should therefore be the goals of SOA Governance and SOA Management,respectively.The model of SOA Governance and SOA Management proposed in this white papercovers all of the above aspects. Although comprehensive, it is nowhere near as complexas current industry recommended best practice would have us believe. In this white paper,all we have done is specify the core entities that exist at each layer of the enterprise, andthe types of dependencies that can occur between them. It is up to the individualorganisation to work out the dependencies that are appropriate to its business, and toensure that these are the only ones that in fact exist.Two logical committees are recommended to oversee the Governance and Managementof the enterprise, respectively, through the application of SOA principles. These two logicalcommittees may translate to a number of physical committees, depending on the size andcomplexity of the organisation. Each committee may in turn set up more specialised teamsto oversee groups of related dependencies.The sample dependency check-lists in Part III can help these committees and theirspecialised teams get started with their tasks. These are based on the BAIT and TOGAFmodels of the enterprise, although re-purposed with a dependency focus to serve as asuite of tools for SOA governance and management.We hope this comprehensive yet lightweight framework enables organisations toimplement SOA Governance and SOA Management quickly and cost-effectively.[Designing systems that are unobtrusive and which ensure rather than enforce correctbehaviour is an intellectual challenge of a higher order, and enterprising organisations maywant to experiment with such “velvet glove” approaches.] 101
  • 101. Contributions of this White PaperWere tempted to call our method the Dependency-Oriented Governance andManagement Approach, but the resulting acronym runs counter to its pragmaticphilosophy!We believe there are several tangible and immediate benefits to anyone who seriouslystudies this white paper.Defining TermsAfter more than a decade of familiarity with the following terms, its disappointing that theindustry still hasnt been able to agree on simple definitions for them. We went back to firstprinciples to see if we could do better.SOA: The science of analysing and managing dependencies.Governance: Ensuring that the right things are done. (The ends, or the “What”.)Management: Ensuring that things are done right. (The means, or the “How”.)SOA Governance: Determining what dependencies are legitimate and what existingdependencies fall outside this set.SOA Management: Dealing with how to remediate illegitimate dependencies, how toformalise legitimate ones and how to prevent the recurrence of violations.Restoring PotentialSOA has been a Cinderella languishing in a technology cellar. This paper crowns it thegoverning principle for the enterprise. We show how to govern with SOA, rather than howto govern SOA.Enterprise Architecture is often criticised as an ivory tower function. This approach gives ita change agents role that will impact an organisations agility, cost and risk in animmediately measurable way.Identifying GapsEnterprise Architecture needs a practical focus to demonstrate value. The focus ondependencies is the missing piece that this paper highlights. 102
  • 102. We have also highlighted the need to inject professional skills from traditionally non-ITbackgrounds into SOA Governance and SOA Management bodies to aid in identifying andremediating dependencies.Simplifying TasksFor all its ambitious scope, the approach outlined here is actually quite simple andminimal. We have provided a listing of the core roles, bodies, functions, processes andcheck-lists that are required to implement it..However, if all you do is add the processes described here on top of the ones you alreadyuse, you will end up with anything but a lightweight approach. What we are audaciouslyrecommending here is that you replace your existing control systems with theseprocesses, fleshing them out only to the extent necessary to meet your businessobjectives.Doubling the Pay-offThe point of this entire white paper is that adopting dependency-orientation as yourenterprises primary organising principle is not only lightweight in itself, but also trims youroperating model overall. Its a double-benefit. 103
  • 103. Potential Criticism of This ApproachWhile we are certain we have contributed something of value to the industry with this whitepaper, we dont believe it will be received without controversy. Initial reviews by peersleads us to believe there could be several angles to the opposition it is likely to provoke.The Weight of TraditionThe first and most obvious source of resistance is from the traditionalist SOA practitionercamp that continues to believe in SOA Governance as a set of processes that bringdiscipline to the way “SOA technology” is used within an organisation.A good thumb rule we would suggest if you ever come across a book/article or an expertwho hews to the traditionalist view of SOA Governance is to check if they are explicitlyrepudiating this white paper. If they make no reference to this document or have neverheard of it, we humbly suggest that our view trumps theirs, since we have taken the painsto rationally rebut the establishment view but they have not reciprocated the courtesy. Ofcourse, if someone from this camp has specific issues with the approach in this whitepaper and is able to make a reasoned argument against it, then by all means listen tothem and use your best judgement.Making Mountains out of MolehillsThe second argument against our approach would probably come from those who see ourdistinction between Governance and Management as splitting hairs. This argument maystate that the functions of Governance and Management as defined here are both to belegitimately considered “Governance”, so the industry is not so badly off-track after all.Our answer is that the “What” and “How” aspects of a decision always go hand in hand,and both are important. Hence our insistence on making a distinction between the twodoes not reduce the effectiveness of these functions, only the confusion between theirconcerns. We dont believe both can be bundled together under the label of “Governance”.On the contrary, it is this conflation that has stifled the real governance function.In both these arguments, you should view this papers approach as a revolution againstthe establishment line, and if you happen to come across a dissenting view, recognise thedifference between a mere old-schooler and a genuine counter-revolutionary. 104
  • 104. Drawing a Long BowA third argument is possibly that this approach overstates the case fordependency-orientation as a comprehensive approach to managing a business, and that acomplete overhaul of the governance and management processes of an organisation tofocus on dependencies is difficult to justify and may even be counterproductive.Our response is that all effort needs to be justified on the basis of costs and benefits. Wehave devoted a fair proportion of this document to detailing true life case studies thatillustrate the high costs entailed by dependencies, no matter what kind of business we dealwith or the level of abstraction we examine. There is serious money to be saved byeliminating dependencies, if organisations will only examine themselves seriously from thisangle. Unfortunately, no major consultancy organisation, industry analyst, B-school guru orprocess tool vendor has yet latched onto dependency-orientation as a buzzword, so this isnot a fashionable thing to do. We flatter ourselves with the possibility that this white papercould just spark such a trend.A Bridge Too FarFinally, there is the “you cant get there from here” argument. The pain here is thewrenching change in focus that the entire organisation will have to undergo. It is a massivere-education exercise with the inevitable missteps, periods of backsliding and moments ofself-doubt that will accompany the effort. First-movers will have an additional disadvantagein that they will have no benchmark to follow and will have to summon up the will to staythe course.But like with any attempt at self-improvement, moving to dependency-orientation isanother instance of “no pain, no gain”. Perhaps the approach can be piloted within asmaller business unit and rolled out more widely once its benefits are demonstrated. 105
  • 105. About the AuthorGanesh Prasad is a Sydney-based architect with over 25 years of experience in the ITindustry and over 10 years as an architect responsible for “Enterprise Shared Services” atdiverse employers such as a leading Australian bank, insurance company and telecomcorporation. He is TOGAF 9 certified and is intimately familiar with warts-and-all SOA as itis practised in large organisations. He has also studied Risk Management as part of adegree in Applied Finance.Ganesh can be contacted at g.c.prasad@gmail.com.AcknowledgementsThanks to (…) for reviewing this white paper.Thanks also to Sushil Gajwani and Ravish Juneja for contributing many of the case studiescited in this document. 106
  • 106. Appendix A – SOA Governance and Management – An Issue of DefinitionIf you do a search on the term “ungulate”, you are probably looking for what is called anintensional definition (“Ungulates are mammals that use the tips of their toes, usuallyhoofed, to sustain their whole body weight while moving”). You would probably not besatisfied with a purely extensional definition (“Ungulates are the horse, zebra, donkey,cattle/bison, rhinoceros, camel, hippopotamus, tapir, goat, pig, sheep, giraffe, okapi,moose, elk, deer, antelope, and gazelle”). The extensional definition can be used as a setof examples to support the intensional one, but isnt very useful on its own.In our own research into the terms “Governance”, “Corporate Governance”, “ITGovernance” and “SOA Governance”, we have been surprised and disappointed to find aplethora of extensional definitions (e.g., “the set of policies, processes, controls andmetrics”) rather than a simple and readily understandable intensional one (i.e., whatgovernance actually is). Such extensional definitions tend to lose the reader at the veryoutset. Without a clear communication of what governance is, any list of terms carries animplicit expectation of rote learning rather than understanding.Sometimes, extensional definitions take the form of a diagrammatic chart that lays outcomponents in a colourful, eye-catching way (such as the ISO 38500 definition of ITGovernance), but even this friendlier format fails to convey what IT Governance really is.Even on the rare occasion when we stumbled upon an intensional definition, it has proventoo fuzzy to be meaningful, e.g., Gartners definition of SOA Governance as “ensuring andvalidating that assets and artifacts within the architecture are acting as expected andmaintaining a certain level of quality”. Does that result in an epiphany on the part of thereader? We suspect not. In the same vein, the Burton Group defines governance as “theprocesses that an enterprise puts in place to ensure that things are done [...] inaccordance with best practices, architectural principles, government regulations, laws, andother determining factors.” This is an extensional definition (a list of things to consider)wrapped up inside an intensional one (a promising definition of governance as a set ofprocesses), with the net result that things are no clearer. 107
  • 107. Many of the definitions of SOA governance are just plain wrong, in our opinion, and theseerrors stem from a fundamental misunderstanding of the scope of SOA. Does SOAGovernance refer to the governance of “SOA assets”, or is it a unique philosophy ofgovernance itself? We believe its the latter, but the industry seems to think its the former.In sum, all of the definitions we have come across have been unsatisfying. We have beenleft to wonder – What is SOA Governance? It seemed rather arrogant to try andsecond-guess an entire industry, but someone had to bell the cat, hence this white paper.Here, we provide simple (and intensional) definitions of both “governance” and“management” that address the confusion between the two terms, with enough extensionaldefinitions as examples to fix these concepts firmly in ones mind. The approach wedescribe is based on these fundamental definitions. 108
  • 108. Appendix B – Lessons from Cadet Camp (or Why SOA is Like a Snakepit)At a high school cadet camp, the author remembers how an instructor walked past a groupof cadets pitching their tent and reminded them to dig a “snakepit” that would keepscorpions and small snakes from entering the tent. One of the cadets dutifully went off anddug a “snakepit” to one side of the tent, as the plan below illustrates. Tent “Snakepit”There was a fair amount of merriment when the instructor came by again and saw whathad been done. The actual concept of a snakepit, as the cadets then learnt, was asillustrated below. Raised Tent “bund” “Snakepit” (trench) 109
  • 109. A snakepit must surround the tent entirely in order to be effective. Digging a pit to one sideof the tent achieves nothing. Snakes and scorpions will not obediently fall into it.In similar fashion, SOA is most effective when its principles are applied across the board.Its not a narrow sub-domain of IT that has to be put into its own little sandpit and managedthere. It informs the way the enterprise is run, no less. Its amazing how many industryluminaries fall prey to this limiting delusion.At the risk of belabouring the point, let us illustrate it graphically below. The Enterprise Pervasive SOA principles SOA “sandpit” 110
  • 110. Appendix C – Core Entities and Dependencies in the TOGAF 9 Model Core Entities Catalogs list Hierarchies of Core Entities. Matrices and Diagrams represent Two-Entity and Multi-Entity Dependencies 111
  • 111. Appendix D – Artifacts In the TOGAF 9 ModelFundamental Enterprise Entities and Dependencies 25Principles CatalogStakeholder Map MatrixValue Chain DiagramBusiness Layer DependenciesBusiness Interaction Matrix (Organisations and Actors)Actor/Role MatrixBusiness Footprint DiagramBusiness Service/Information DiagramFunctional Decomposition DiagramGoal/Objective/Service DiagramBusiness Use-Case DiagramOrganisation Decomposition Diagram (Actors, Roles and Location)Process Flow DiagramEvent Diagram (Events and Processes)Application Layer DependenciesSystem/Organisation MatrixRole/System Matrix25 TOGAF does not identify the “Driver/Goal/Objective Catalog” as part of the Preliminary or ArchitectureVision phases (which correspond to the fundamental Enterprise level) but as part of the BusinessArchitecture phase. However, our experience with enterprise utilities/shared services tells us that Goalsapply at the overall enterprise level as well as at the level of business unit silos below it, and the dichotomy isoften critical. Thats why we include it in our set of Enterprise Dependencies as well as Business LayerDependencies.. 112
  • 112. Application Interaction MatrixSystem/Function MatrixApplication Communication DiagramApplication and User Location DiagramSystem Use-Case DiagramEnterprise Manageability DiagramProcess/System Realisation DiagramApplication Migration DiagramSoftware Distribution DiagramSoftware Engineering DiagramInformation (Data) Layer DependenciesData Entity/Business Function MatrixBusiness Service/Information MatrixSystem/Data MatrixClass DiagramData Dissemination DiagramData Life-Cycle DiagramData Security DiagramData Migration DiagramClass Hierarchy DiagramTechnology Layer DependenciesSystem/Technology MatrixEnvironments and Locations DiagramPlatform Decomposition DiagramProcessing Diagram 113
  • 113. Networked Computing and Hardware DiagramCommunications Engineering Diagram 114
  • 114. Appendix E – References1. Wikipedia: http://bit.ly/HyPBBE2. Dave Olivers blog entry: http://bit.ly/H5mzY2(A lone blogger gets it right where giants like IBM and the Burton Group fail. He doesnt gofar enough, however, preferring to restrict the scope of SOA to just IT.)3. IBMs entry: http://ibm.co/qm464. Towards a reference model for SOA Governance: http://bit.ly/H4yjKP5. Forrester SOA Value Assessment: http://bit.ly/H4ynu46. SOA Softwares reference model: http://bit.ly/HvuRYq(Two fundamental layers; an application and messaging services layer, and aninfrastructure services layer.)7. Burton Group on SOA and Governance: http://bit.ly/HFdF6t(Extensional definition: What is a governance program? Policies, Processes, Metrics,Organisation)Confusion on slides 2 and 5 (doing the right thing versus doing things right)8. The reincarnation of SOA: http://bit.ly/9aowov9. Resurrecting SOA: http://bit.ly/aQMCRk10. You cant buy governance: http://bit.ly/HaRxkx(confusion on pages 2 and 5 – doing the right thing versus doing things right)IT governance:11. Confuse, scare and sell: http://bit.ly/c8ZD12. ISO 38500: http://bit.ly/j3Ym4H(Extensional definition in the form of a chart)13. CIO.com article: http://bit.ly/pz2lr114. Simplicable model: http://bit.ly/Hb5NcMCorporate Governance:15. Wikipedia: http://bit.ly/XsnAz 115
  • 115. 16. ASX: http://bit.ly/HlhO6F(Partly intensional, partly extensional, useful principles)17. SearchFinancialSecurity: http://bit.ly/e9x20x(Extensional definition)18. Auditors perspective: http://bit.ly/pkwHKh(Extensional definition: Corporate governance is the set of processes, customs, policies,laws, management practices and institutions affecting the way an entity is controlled andmanaged.)19. Data on the Outside vs. Data on the Inside: http://bit.ly/RHj7dp(Seminal paper by Pat Helland) 116