Soa

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  • 2003 PSS Global Summit
  • 2003 PSS Global Summit
  • 2003 PSS Global Summit Emphasize that the rationale for the architectural decisions is very important.
  • 2003 PSS Global Summit Software architecture is the collection of the fundamental decisions about a software product/solution designed to meet the project's quality attributes (i.e. requirements). The architecture includes the main components, their main attributes, and their collaboration (i.e. interactions and behavior) to meet the quality attributes. Architecture can and usually should be expressed in several levels of abstraction (depending on the project's size).   If an architecture is to be intentional (rather than accidental), it should be communicated. Architecture is communicated from multiple viewpoints to cater the needs of the different stakeholders. Every system has an architecture, even if it is not formally “spec’ed out”.
  • A Solution to world hunger Not a solution for everything Just another tool in the toolset A specific Technology Most notably SOA  Web Services Will Not make all code reusable A New name for EAI Though well established contracts can help that too A New way to do RPC 2003 PSS Global Summit
  • 2003 PSS Global Summit
  • 2003 PSS Global Summit
  • Business Alignment Can’t stress that enough Reduced assumptions (loose coupling) Builds on ideas from component software, distributed objects, and MOM BPM … All the stuff enterprise architects do 2003 PSS Global Summit
  • A service is a program you interact with via message exchanges Services are built to last Encompass a business perspective Stability and robustness are critical A system is a set of deployed services cooperating in a given task Systems are built to change Adapt to new services after deployment 2003 PSS Global Summit
  • Each Service interaction is a boundary crossing Don’t cross it with transactions / exceptions etc. Crossing service boundaries may have costs Service Orientation helps makes interaction formal, intentional, and explicit Service boundary is a trust boundary ! Respect my Boundaries (Adopted from Alex Weinert, Clemens Vasters) 2003 PSS Global Summit
  • Autonomous services can mean many things. One explanation I’ve heard was the autonomous means that the teams working on different teams can be autonomous. While, this is a nice “feature” to have, a much more valuable (as in “business value”) definition is that the services are as self sufficient as possible. For example a imagine a journal subscription agency which needs to create a proposal for a client. The proposal service needs among other things, to produce a “pro forma” invoice in order to do that it must get the customer’s discount rate and the customer’s discount rate as well as the publisher’s discount rates (to check if the proposal is profitable) see the flow in figure 2.X below . If the proposal service is not autonomous it has to wait for two other services and while the customer service is local the publisher’s discount might be a remote one (on the publisher’s system) – what happens to our proposal service if the publisher’s system is not on-line? 2003 PSS Global Summit
  • Service compatibility is determined based on policy Object-oriented designs often confuse structural compatibility with semantic compatibility. Service-orientation deals with these two axes separately. Structural compatibility is based on contract and schema and can be validated (if not enforced) by machine-based techniques (such as packet-sniffing, validating firewalls). Semantic compatibility is based on explicit statements of capabilities and requirements in the form of policy.   Every service advertises its capabilities and requirements in the form of a machine-readable policy expression. Policy expressions indicate which conditions and guarantees (called assertions) must hold true to enable the normal operation of the service. Policy assertions are identified by a stable and globally unique name whose meaning is consistent in time and space no matter which service the assertion is applied to. Policy assertions may also have parameters that qualify the exact interpretation of the assertion. Individual policy assertions are opaque to the system at large, which enables implementations to apply simple propositional logic to determine service compatibility. A Policy is a set of assertions made about Security messages behavior level of service limited by the actual service capabilities Policy-sets are attached, embedded or otherwise associated with contracts Policy specifies a run-time dynamic, negotiable configuration information for a contract implementation. 2003 PSS Global Summit
  • 2003 PSS Global Summit Took Clemens example – but Reversed contract direction – The is “owned” by the service provider not the consumer
  • address, a URI, a specific place where the service can be found. A specific contract can be exposed at a specific endpoint. 2003 PSS Global Summit
  • Services Revolve Around Messages Services Are “Black Boxes” Messages go in and out The Rest Is an Implementation Detail! 2003 PSS Global Summit
  • Between Services is Special Messages Are Sent and Float Around Between Special Care Is Needed to Understand Them Can Be Confusion About Interpreting Them Many Kinds of Message transports Email, IP, TCP/IP, HTTP, Web-service, MSMQ, MQ-Series, and more Many Kinds of Message structures XML, Binary, whatever May be OK to Have Some Message Loss If messages are idempotent Other option “Reliable Messaging” 2003 PSS Global Summit
  • 2003 PSS Global Summit
  • One Way Incoming Outgoing Broadcast Publish (as in publish/subscribe) To single recipient Duplex Two one-ways Request/Reply R equest/Reaction 2003 PSS Global Summit
  • Messages & Formats Message Exchange Patterns Where is a service located (Address) Protocol & content format (Binding) 2003 PSS Global Summit
  • Service Data is private Keep DB private Keep transactions private Keep exceptions private Don’t share classes or other internal data structures Don’t share too much – or you’ll lose autonomy (or tempt others to lose it) 2003 PSS Global Summit
  • Services interactions are message driven Services should be Loosely coupled Edges should provide location transparency Business logic and edge are separate layers Scale inside the service You can use workflows for long-running interactions again - inside the service 2003 PSS Global Summit
  • Soa

    1. 1. Service OrientedService Oriented ArchitectureArchitecture An IntroductionAn Introduction Arnon Rotem-Gal-OzArnon Rotem-Gal-Oz Biometrics Line DevelopmentBiometrics Line Development ManagerManager
    2. 2. What is Software ArchitectureWhat is Software Architecture
    3. 3. What is ArchitectureWhat is Architecture Formal DefinitionFormal Definition  IEEE 1471-2000IEEE 1471-2000  Software architecture is theSoftware architecture is the fundamentalfundamental organizationorganization of a system, embodied in itsof a system, embodied in its componentscomponents, their, their relationshipsrelationships to each other andto each other and the environment, and thethe environment, and the principlesprinciples governing itsgoverning its design and evolutiondesign and evolution IEEE 1471-2000IEEE 1471-2000
    4. 4.  collection of the fundamental decisions about a softwarecollection of the fundamental decisions about a software product/solution designed to meet the project‘s qualityproduct/solution designed to meet the project‘s quality attributesattributes  Includes the main components, their main attributes, and theirIncludes the main components, their main attributes, and their collaborationcollaboration  expressed in several levels of abstraction (depending on theexpressed in several levels of abstraction (depending on the project's size).project's size).  Architecture is communicated from multiple viewpointsArchitecture is communicated from multiple viewpoints What is Software ArchitectureWhat is Software Architecture
    5. 5. QualityQuality AttributesAttributes
    6. 6. How ArchitectureHow Architecture ArchitectureArchitecture QualityQuality AttributesAttributes TechnologyTechnology Patterns &Patterns & Anti-patternsAnti-patterns PrinciplesPrinciples CommunityCommunity experienceexperience CommunityCommunity experienceexperience StakeholdersStakeholdersStakeholdersStakeholders ArchitectArchitectArchitectArchitect peoplepeople A “deliverable”A “deliverable” ProduceProduce KeyKey Is an inputIs an input ConstraintsConstraints
    7. 7. What is a Service (1)What is a Service (1) Merriam-WebsterMerriam-Webster  A facility supplying some public demandA facility supplying some public demand  the work performed by one that serves HELP, USE,the work performed by one that serves HELP, USE, BENEFITBENEFIT HMM..HMM..
    8. 8. What is a Service (2)What is a Service (2)  In economics and marketing, a service is the non-In economics and marketing, a service is the non- material equivalent of a good. Service provision hasmaterial equivalent of a good. Service provision has been defined as an economic activity that does notbeen defined as an economic activity that does not result in ownership, and this is what differentiates itresult in ownership, and this is what differentiates it from providing physical goods.from providing physical goods.  It is claimed to be aIt is claimed to be a process that creates benefitsprocess that creates benefits byby facilitating either a change in customers, a changefacilitating either a change in customers, a change in their physical possessions, or a change in theirin their physical possessions, or a change in their intangible assets.intangible assets. en.wikipedia.org/wiki/Serviceen.wikipedia.org/wiki/Service
    9. 9. What is a service (3)What is a service (3)  A Windows Service?A Windows Service?  RPC Locator, EventLog, DHCP Client,RPC Locator, EventLog, DHCP Client,  Software Service?Software Service?  Distribution Service, Alert ServiceDistribution Service, Alert Service  Security Service, Log ServiceSecurity Service, Log Service  Business Service?Business Service?  Common Operational Picture, NavigationCommon Operational Picture, Navigation  Accounts Receivable, CustomersAccounts Receivable, Customers
    10. 10. SOA isn’t a solution toSOA isn’t a solution to world hungerworld hunger Nor is it:Nor is it:  A specific TechnologyA specific Technology  The Ultimate answer to reuseThe Ultimate answer to reuse  AA New name for EAINew name for EAI  A New way to do RPCA New way to do RPC
    11. 11. ASBASB BLTBLT HDLHDL AFTAFT TGITGI FRYFRY DRWDRW SWGSWG QYDQYD DLYDLY BSTBST WIUWIU ASBASB ZISZISXOIXOI CUICUI RMORMO DLYDLY XPSXPS KYFKYF KFCKFC WHRWHR JIAJIA GEXGEX FQAFQAVUHVUH HCOHCO WKDWKD ECPECP SKDSKD MFPMFP WCPWCP DKEDKEAJTAJT Big SOABig SOA Analyze the businessAnalyze the business
    12. 12. ASBASB BLTBLT HDLHDL AFTAFT TGITGI FRYFRY DRWDRW SWGSWG QYDQYD DLYDLY BSTBST WIUWIU ASBASB ZISZISXOIXOI CUICUI RMORMO DLYDLY XPSXPS KYFKYF KFCKFC WHRWHR JIAJIA GEXGEX FQAFQAVUHVUH HCOHCO WKDWKD ECPECP SKDSKD MFPMFP WCPWCP DKEDKEAJTAJT Big SOABig SOA Identify Business AreasIdentify Business Areas COP Navigation Protectors Alerts
    13. 13. Big SOABig SOA Map to softwareMap to software "Network" COPCOPCOPCOP Nav.Nav.Nav.Nav. AlertsAlertsAlertsAlerts Prot.Prot.Prot.Prot.
    14. 14. Little SOALittle SOA  Architectural StyleArchitectural Style  For building distributed systemsFor building distributed systems  Loosely coupled componentsLoosely coupled components  Our focus from here onward…Our focus from here onward…
    15. 15. ServiceService describesdescribes End PointEnd Point ExposesExposes MessagesMessages Sends/ReceivesSends/Receives ContractsContracts Binds toBinds to ServiceService ConsumerConsumer implementsimplements PolicyPolicy governed bygoverned by Sends/ReceivesSends/Receives AdheresAdheres toto ComponentComponent RelationRelation KeyKey UnderstandsUnderstands ServesServes
    16. 16. Services and SystemsServices and Systems  A service is a program you interact withA service is a program you interact with via message exchangesvia message exchanges  A system is a set of deployed servicesA system is a set of deployed services cooperating in a given taskcooperating in a given task
    17. 17. A Service edgeA Service edge is a naturalis a natural boundaryboundary Warning: Remoting and other RPCs trick us into thinking that there is no substantial difference between a local and a remote object. In fact, they hide the presence of the network.
    18. 18. Services are AutonomousServices are Autonomous
    19. 19. sd Autonomous Services User Journal Subscription System Publisher X User «service» Customer «service» Proposals «service» Proposals Waiting on external resources do we really know how long will it take? Not to mention that getting the information only when needed makes Service interaction very RPC-like (but that's another problem) 1.0 getProforma 1.1 getCustomerDiscount 1.2 1.3 getDiscountRate 1.4 1.5 XX
    20. 20. sd ActiveServ ice User Journal Subscription System Publisher X User «service» Customer «service» Proposals «service» Proposals note that now we are getting all the dicount rates in one call (less messages) to generate even less traffic the contracts can be made to include only changes from timestamp supplied in the request loop Activ e Class polls external resources 1.0 getCustomerDiscounts 1.1 1.2 getDiscounts 1.3 2.0 ProduceProforma 2.1
    21. 21. The fact that I can, doesn’t mean I will. PoliciesPolicies
    22. 22. Organization AOrganization A Organization BOrganization B PolicyPolicy PolicyPolicy Policy IllustratedPolicy Illustrated Buyer ServiceBuyer Service Local ServiceLocal Service Local ServiceLocal Service Seller ServiceSeller Service Runtime contractRuntime contract Runtime ContractRuntime Contract 1. Use X.509 Cert for AuthN1. Use X.509 Cert for AuthN 2. Use UTF-8, SOAP 1.22. Use UTF-8, SOAP 1.2 …… PolicyPolicy 1. Supports X.509 Cert1. Supports X.509 Cert oror Kerberos ST for AuthNKerberos ST for AuthN 2. Supports UTF-8, UTF-16, SOAP 1.2, 1.12. Supports UTF-8, UTF-16, SOAP 1.2, 1.1 …… Adopted from Clemens VastersAdopted from Clemens Vasters Design time ContractDesign time Contract 1. You’ll send a PO1. You’ll send a PO 2. I’ll send a confirmation2. I’ll send a confirmation ……
    23. 23. EndpointEndpoint
    24. 24. It’s all about theIt’s all about the Message, baby!Message, baby!
    25. 25. MessagesMessages travel intravel in no man’s land!no man’s land!
    26. 26. Is heIs he Idempotent?Idempotent? MessagesMessages GetGet RetransmittedRetransmitted MessagesMessages ArriveArrive More thanMore than onceonce
    27. 27. IdempotenceIdempotence  Idempotent Means It’s OK to Arrive Multiple TimesIdempotent Means It’s OK to Arrive Multiple Times  As Long as the Request Is Processed at Least Once, the CorrectAs Long as the Request Is Processed at Least Once, the Correct Stuff OccursStuff Occurs  In Today’s Internet, You Must Design Your Requests to BeIn Today’s Internet, You Must Design Your Requests to Be IdempotentIdempotent Not IdempotentNot Idempotent Baking a CakeBaking a Cake Starting fromStarting from IngredientsIngredients Naturally IdempotentNaturally Idempotent Sweeping the FloorSweeping the Floor Naturally IdempotentNaturally Idempotent Read Record “X”Read Record “X” IdempotentIdempotent If Haven’t Yet DoneIf Haven’t Yet Done Withdrawal #XYZWithdrawal #XYZ for $1 Billion,for $1 Billion, Then WithdrawThen Withdraw $1 Billion and$1 Billion and Label as #XYZLabel as #XYZ Not IdempotentNot Idempotent WithdrawingWithdrawing $1 Billion$1 Billion IdempotentIdempotent Baking a CakeBaking a Cake Starting fromStarting from the Shoppingthe Shopping List (If MoneyList (If Money Doesn’t Matter)Doesn’t Matter) Pat HellandPat Helland
    28. 28. Message Exchange PatternsMessage Exchange Patterns
    29. 29. Request/ReplyRequest/Reply Request/ReactionRequest/Reaction VSVS
    30. 30. Decoupled Invocation PatternDecoupled Invocation Pattern
    31. 31. ServiceService ContractContract
    32. 32. Keep Data and state privateKeep Data and state private
    33. 33.  Big SOA is about business alignmentBig SOA is about business alignment  Little SOA is an Architectural StyleLittle SOA is an Architectural Style  Autonomous Coarse GrainedAutonomous Coarse Grained ComponentsComponents  Message based InteractionsMessage based Interactions  Run-Time configurationRun-Time configuration
    34. 34. What’s nextWhat’s next  SOA Structural PatternsSOA Structural Patterns  SOA Interaction PatternsSOA Interaction Patterns  UI Interaction PatternsUI Interaction Patterns  Service Composition PatternsService Composition Patterns  Contract Anti-patternsContract Anti-patterns  Service Anti-patternsService Anti-patterns  SOA Performance Anti-PatternsSOA Performance Anti-Patterns

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