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How to save on software maintenance costs






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    How to save on software maintenance costs How to save on software maintenance costs Document Transcript

    • Omnext white paper, March 2010How to save on software maintenance costsAbstractThe cost of software maintenance is rising dramatically and it has been estimated in [1] thatnowadays software maintenance accounts for more than 90% of the total cost of software,whereas it was around 50% a couple of decades ago. There are several reasons for this. Wecan see that software systems become hard to maintain over time, while every day more andmore software is being produced.Documentation is lacking or incomplete and the people who know the software leave orretire without being replaced. Furthermore, systems tend to become increasingly complex.This makes extending a system difficult and costly. Rebuilding a system is usually not anoption because the system that needs to be replaced is large, the test coverage unknown andthe original and modified requirements are not well documented. 100% = Total cost of software 100% 50% Maintenance costs 1970 2009 Figure 1: Development of Software maintenance costs as percentage of total costGiven the enormous costs and efforts involved in software maintenance, every companyshould consider ways to make savings here, as also observed in [15]. This paper presentsseveral known ways to save on software maintenance costs, and it also presents anintegrated approach developed by Omnext. Page 1 of 12
    • Introduction and cost driversSeveral best practices for the process optimization of software maintenance activities can beapplied, such as CMMI [10], ITIL [23] and ASL/BISL [12]. All of these focus on theoptimization of processes. What is at least as interesting, however, is where the real costs ofsoftware maintenance lie. Until recently [2, slide 6, 2002 and 6, 2008] relatively little wasknown about the software maintenance process and the factors that influence the cost of it.An investigation of recent reports about the costs of software maintenance has uncoveredthe following.The costs of understandingMaintenance consists of a number of different activities, as shown in figure 2. One of the keyissues that needs to be dealt with is limited understanding. Limited understanding refers tohow quickly a software engineer can understand where to make a change or correction insoftware. Some 40-60% of the maintenance effort is devoted to this task, as is noted in theGuide to the Software Engineering Body of Knowledge (SWEBOK) [3].Thus, the topic ofsoftware comprehension is of great interest to the software world. Figure 2: Analyzing is almost 50% of the total maintenance effortThe costs of ‘lack of’ or ‘little’ documentationOne way to remedy limited understanding is to produce documentation and othersupporting descriptions such as data- or UML-models. However, how much documentationis enough? This topic was investigated during the twenty-third annual internationalconference on the design of communication [13, 2005], which reached the followingconclusion: The surveys confirmed that source code and comments are the most importantartifacts for understanding a system to be maintained.Data model and requirement description were other important artifacts. Surprisingly, andcontrary to what we found in the literature, architectural models and other general views ofthe system were not found to be very important.How to save on software maintenance costs Page 2 of 12
    • The two central costs of a developer’s effortIn [6] it is argued that software engineering practices can be improved if they address factorsthat have been shown empirically to affect a developer’s effort during software evolution.The two central finding were that:1. The volatility of requirements had a large and consistently negative effect on effort.2. The dispersion of changed code (distribution over different files/components) also had a large and consistently negative effect on change effort. Typically, the change requests were described by referencing a user scenario, i.e. a sequence of interactions between the user and the system, and by requesting a change to that scenario. The developers expressed that considerable time was spent understanding relevant, intermediate code when it was dispersed over many files. In other words, the qualitative data shows that when code involved in the changed user scenario was dispersed over many components that user scenario was difficult to change.Other costs involvedOther cost factors in software maintenance are, among others, lack of programmingstandards and guidelines, solving bugs and problems, implementing changes, testing, impactanalysis and integration with other systems. Any speedup in these areas would help reducecosts.The above explains what is known about the aspects that influence the costs of operationalsoftware maintenance. The next sections will be a summary of some of the practical costsavings possibilities presented in the literature.Six ways to save(Re)documentationMost existing systems are often poorly documented [5, 9]. Below we refer to several casestudies where money could be saved by (re)documentation.• In one of the few controlled experiments relating to this topic, research [5] has shown that the programmers who had no documentation spent 21.5% longer understanding the code. Knowing that understanding may take around 50% of the total costs of software maintenance, we could save 12% of the total cost of software maintenance if we had documentation in place. Another particularly interesting result was that, without documentation, differences in skill levels between good and bad programmers disappeared. With documentation, good programmers did better work than poor programmers did. Without documentation, they both did equally bad work. Consequently, spending money on the best people is a waste without documentation.How to save on software maintenance costs Page 3 of 12
    • • Other gains of (re)documentation are reported in [18] where the break-even point occurred after 1.5 years of effort, which means that the extra investment in (re)documentation started paying off after 1.5 years of (re)documentation activity.• In [6] and also quoted in our introduction, it is said that the need to understand dispersed code is one of the two main cost factors of software maintenance, so having documentation of the dispersed code along a user scenario would significantly help.Eliminating dead codeIt is reported [16, 17] that up to 30% of the software in an older system can be dead code. Byeliminating dead code, we reduce the code size. For an introduction to eliminating deadcode and why it is important, we refer to [16]:Dead codeDead code means unnecessary, inoperative code that can be removed without affecting theprogram functionality.Dead code includes functions and sub-programs that are never called, properties that arenever read or written, and constants and enums that are never referenced. Variables shouldbe both read and written to. User-defined types can also be dead and a project may containredundant API declarations. Even entire modules and classes can be completely redundant.The opposite of dead code is live, operational code. There are also several types of semi-deadcode, that is, live-looking code and controls that are not actually required at run-time.Below we present several reasons for why we should care about dead code.• Dead code is a very common phenomenon. It can account for 30-40% of a projects size and increase the EXE or DLL file size by hundreds of kilobytes. The average amount of dead code is 15%. The more developers there are, the tighter the deadlines, the older and larger the system, the more dead code there is.• Dead code means excessive memory use and slower execution. It also means more code to read and maintain. It leads to higher costs, especially during maintenance. If the code is present, programmers must spend time understanding it.• Leaving dead code in a completed project means carrying around untested code and hidden bugs. Dead code may inadvertently become operative later, meaning a possible source for errors.• If you are considering the purchase of someones source, make sure that you are not paying for hundreds of thousands of unnecessary lines. If you just took on a new project, the first thing to do should be to remove any significant dead parts. If you are finishing your newest release, remove the dead bits to ease future maintenance efforts.As reported in [19], the savings can be significant. It will cost at least $1.00 per source lineper year to maintain application software. Costs for the maintenance of both dead code aswell as active code are therefore estimated to be at least $1.00 per source line.How to save on software maintenance costs Page 4 of 12
    • Eliminating cloned codeWhen applying new functionality, many programmers cannot resist the temptation to copy(clone) and customize existing pieces of code. The problem with this approach is that bugsare copied as well and future modifications may have to be applied to each clone, which isan error-prone procedure. Large software systems typically contain 10-25% of such clonedcode. This introduces extra maintenance costs above the standard $1.00 per source line. Thenumber of clones can be reduced by isolating the clone code in a (possibly parameterized)subprogram.It is reported in [19] that considerable savings on maintenance can be achieved by keepingthe amount of cloned code to a minimum. We quote them below.Cloned codeLarge software systems typically contain 10-25% redundant code. This redundancy is causedby the common programming practice of replicating (or cloning) existing code and thencustomizing to handle new demands on an application. An IT organization consequentlyspends corresponding amounts of its budget redundantly maintaining this code; a bug in onecode fragment is also a bug in all of its hidden clones.If redundant code were removed, the IT organization could spend the budget savings onsolving new problems, enhancing the efficiency of the parent organization. The savings canbe significant, because it typically costs, as stated earlier in reference to dead codeelimination, at least $1.00 per source line per year to keep application software in runningorder.Avoiding and eliminating bugsAvoiding and eliminating bugs are on the rise. The following is noted in [20].BugsBugs in software are costly and difficult to find and fix. In recent years, many tools (likeBandera, ESC/Java2, FindBugs, JLint, and PMD) and techniques have been developed forautomatically finding bugs by analyzing source code or intermediate code statically (atcompile time). These tools look for bug patterns which are code idioms that are often errorsor potential problems. Sometimes these patterns are covered by local Standards andGuidelines or programming rules. An example is an empty catch block. In code with an emptycatch block an exception is caught, but nothing is done. In most circumstances, this swallowsan exception which should either be acted on or reported. Another example is an empty ifstatement. In an empty if statement a condition is checked but nothing is done about it.Either remove them or act upon them.In [20], Hovemeyer and Pugh relate their experiences of applying bug pattern detectors toprograms. They have drawn several interesting conclusions about why you should applythem.How to save on software maintenance costs Page 5 of 12
    • …..“First, we have found that even well tested code written by experts contains a surprisingnumber of obvious bugs. Second, Java (and similar languages) has many language featuresand APIs which are prone to misuse. Third, we found that simple automatic techniques canbe effective at countering the impact of both ordinary mistakes and misunderstood languagefeatures.”….The above experience combined with the rule of thumb often adhered to that fixing one bugcosts about $1.000 makes preventing or eliminating bugs an attractive option.Focused test activitiesIn [21], regression testing techniques are discussed and classified. The authors point out thatthe “retest all method” is a conventional method for regression testing, in which all the testsin the existing test suite are rerun.This “retest all” technique has proven very expensive compared with other techniques theydiscuss. At the heart of these techniques lies the observation that unmodified parts ofprograms need less test attention. So only focusing on modified parts leads to lessregression test time and therefore substantial cost savings.In general: Reducing complexity leads to improved maintainabilityIn [4] it is argued that considerable savings can be achieved by monitoring and improving thetechnical quality of a system before and during maintenance. This is also confirmed in [22],where the following conclusion is drawn: On the basis of software maintenance projects in acommercial application environment, it was confirmed that software maintenance costs aresignificantly affected by the levels of existing software complexity. The analysis on this sitesuggests that high levels of software complexity account for approximately 25%maintenance costs or more than 17% of total life-cycle costs. Given the extremely high costof maintenance in commercial applications, the neglect of software complexity is potentiallya serious omission.An integrated approachThus far we have seen six possible ways to save costs and improve quality. What we arelooking for is a practical integrated approach to identify these possible ways and apply them.During the past decade, Omnext has developed CARE, a concept that offers an integratedand systematic approach to cost reductions. CARE stands for Computer Aided(Re)documentation & Evaluation. At the heart of this concept lies the idea of continuousincremental improvement [much like the Kaizen [8] principle]. CARE allows you to generatesavings of up to 50% on the costs of, among others, impact analysis, testing, anddocumenting. Furthermore, it enables you to improve the quality of your software.How to save on software maintenance costs Page 6 of 12
    • The concept comprises the computer-aided construction of technical and functionaldocumentation (in the case of Omnext, this is realized through the use of its own proprietarydeveloped technology Source2VALUE*). The concept also encompasses the automatedmonitoring of a software system’s quality and size. Suggestions for improvement will bemade on the results that are found, suggestions for improvement will be proposed. CAREcan be tailored to situation in which it is used. Figure 3: CARE(* Source2VALUE™ is a flexible technology environment that allows you to document andevaluate your systems periodically. This is done by automatically analyzing the source code,workflow definitions, menu structures, and batch-job definitions.)How to save on software maintenance costs Page 7 of 12
    • • Intake: A CARE environment is defined depending on the domain for which you wish to have a software documentation and software evaluation environment. The result, the CARE definition, is a clear specification of the application software sources to be analyzed, the standards, and the method of documentation and evaluation. • Monitor: Monitoring based on the CARE definition in order to analyze the application sources automatically and periodically. The result is a repository with quality and size measurements. For documentation purposes, this repository also contains all the structures and relationships of and between the application sources. The result is a data warehouse containing all the application sources and characteristics • Report: A variety of reports can be generated from the object in the repository. These may contain information about quality, size, and trend development. The technical documentation is also generated. In addition, the functional documentation that may need to be adapted is identified from the changes in the application. • Analyze: Analysis is carried out by looking at signals, quality, and productivity KPIs, and then turning the results into recommendations for improvement. The functional documentation is also analyzed from the signals. • Improve: Improvement occurs by implementing the improvement recommendations and updating the functional documentation. This updating is carried out manually or is automatically supported by tooling. If required, the CARE definition can be updated on the basis of advanced insight.We illustrate below how the ‘six ways to save’ from above can reduce maintenance costs.Source2VALUE™Omnext’s Source2VALUE product supports (re)documentation by automatically generatingtechnical documentation and semi-automatically generating functional documentationthrough the Use Case Editor (UCE). The UCE enables you to reproduce the functionalworking of an implemented application at a fast speed. The UCE can be deployed repeatedly,so you can guarantee that functional changes reflect the actual current source code.In summary, it provides the following functionality:• Use Case Recovery: This allows you to reproduce the functional operation of your application quickly from the source code• Business Rule Harvesting: This allows you to distill the business rules from your source code• Update signaling: This signals, on the basis of changes of source code, where you need to update your functional documentationIn addition, Source2VALUE also provides insight into the quality, size, and functioning of theanalyzed application. This relates to, among others, source code, workflow definitions, menustructures, and batch-job definitions. This way you are given an insight into:How to save on software maintenance costs Page 8 of 12
    • • the metrics for software quality and size• the trend of the metrics for software quality and size• the structure and functioning of the application• the application source code (dead and cloned code)• the relationships between the different application components• the system workflow• specification of differences in different application versionsBusiness BenefitsIn the “Six ways to save” section, we presented possible savings from the literature. Afterapplying one or more improvements, the maintenance costs will decrease, as shown inFigure 4. Note that the actual maintenance costs vary from system to system. In this case,three trend lines for the development of software maintenance costs over time are given. Software Maintenance costs CARE Time Figure 4: Effect of CAREIf you are wondering what the real savings could be, Table 1 below shows a combination ofpossible savings, as reported in the literature. In this case, a hypothetical system of onemillion lines of code, with average maintenance costs of one dollar per line of code per year[19] has been chosen. Ways to save Literature source Savings in literature Possible savings (Re)documentation [5] 10 - 25% $100.000-$250.000 Dead code [16] 30 - 40% $300.000-$400.000 Cloned code [19] 10 - 25% $100.000-$250.000 10 avoided bugs, Avoiding bugs General experience $500-$1000 per bug fix $5.000-$10.000 General complexity [22] up to 25% $250.000 Table 1: Mentioned savings in literatureHow to save on software maintenance costs Page 9 of 12
    • Note that in reality the overall possible savings will most likely be lower. However, if yousuppose that even the saving possibilities that we have mentioned result in an overallscenario where savings are 30% ($300.000), then you would achieve a substantial benefit interms of costs, not to mention the positive overall effects on quality and productivity for allmaintenance efforts.SummaryWe have presented six ways from the literature to save software maintenance costs. Theseare often based on empirical studies. We then described the Omnext CARE concept, apractical solution for establishing continuous incremental improvement and thus loweringsoftware maintenance costs. Furthermore, we described the unique state-of-the-artcapabilities of Omnext’s Source2VALUE technology. Finally, using an integrated approach,we presented the financial benefits for your business, which, as we have seen, can besubstantial.Call to actionAfter reading this paper one thing should be clear. Saving on maintenance costs will neverbe achieved with one major action. It calls for an integrated approach, preferablyinstitutionalized in the company’s own software maintenance area. Practical information onsoftware system(s) combined with the right supportive technology and the right approach(where relevant aspects get their attention) is needed. Only then can software maintenancecosts be lowered and kept low in a sustainable way.AuthorsIr. Floris P. Engelbertink, Omnext, e-mail: floris.engelbertink@omnext.netDr. Harald H. Vogt, Omnext, e-mail: harald.vogt@omnext.netReferences and links1. Software Maintenance Costs, Ó Jussi Koskinen, Information Technology Research Institute, ELTIS-project, University of Jyväskylä, Finland, http://users.jyu.fi/~koskinen/smcosts.htm2. Estimating Software Maintenance, Seminar 2002, Arun Mukhija, Institut fur Informatik der Universität Zurich, http://www.ifi.uzh.ch/rerg/fileadmin/downloads/teaching/seminars/seminar_ws0203/S lides_9.pdf3. Guide to the Software Engineering Body of Knowledge (SWEBOK), http://www.computer.org/portal/web/swebok/html/ch6#Ref1.14. Softwaremonitoring, Lagere TCO door kwaliteitscontroles, SIG, http://www.software- improvers.com/blobs/Publicaties/Publicaties%202009/20091104%20Lagere%20TCO%20 door%20kwaliteitscontrole.pdf5. Report from an experiment : impact of documentation on maintenance in Journal of empirical software engineering, Tryggeseth, Eirik, Kluwer Academic 2: 2, 201-207 1997 ISSN 1382-3256, http://www.realisation.com.au/site1/Articles/Reducing%20software%20maintenance% 20costs.htm6. An investigation of change effort in two evolving software systems, Technical report 11/2008, Simula Research Laboratory, related paper appeared as “Understanding costHow to save on software maintenance costs Page 10 of 12
    • drivers of software evolution: a quantitative and qualitative investigation of change effort in two evolving software systems” in Journal Empirical Software Engineering, http://simula.no/research/se/publications/Simula.SE.317/simula_pdf_file7. Software Evolution, Universität Bern, Lecture, Tudor Gîrba, http://scg.unibe.ch/download/evo/01-introduction.key.pdf8. Kaizen, The Japanese Strategy of Continuous Improvement, http://www.1000ventures.com/business_guide/mgmt_kaizen_main.html9. A Survey on the Software Maintenance Process , Proceedings of the International Conference on Software Maintenance, Maria Joao Sousa, Page: 265, Year of Publication: 1998, http://portal.acm.org/citation.cfm?id=85330010. CMMI for Development, Version 1.2 , Technical Report, CMU/SEI-2006-TR-008, Software Engineering Institute, http://www.sei.cmu.edu/library/abstracts/reports/06tr008.cfm11. ASL BiSL Foundation, Website, http://www.aslbislfoundation.org/component/option,com_docman/task,cat_view/gid,1 0/Itemid,24/lang,nl/12. CMMI: Overstappen, waarom en hoe?, Henk Westerink, Rini van Solingen en Eric van der Vliet , LogicaCMG, http://www.dse.nl/~thelosen/artikelen/Final%20CMMI%20Overstappen%20waarom%2 0en%20hoe.pdf13. A study of the documentation essential to software maintenance, ACM Special Interest Group for Design of Communication, Proceedings of the 23rd annual international conference on Design of communication: documenting & designing for pervasive information, Sergio Cozzetti B. de Souza , Nicolas Anquetil, Káthia M. de Oliveira Universidade Católica de Brasília, Brasilia, Brazil http://portal.acm.org/citation.cfm?id=1085331&dl=GUIDE&coll=GUIDE&CFID=72997626 &CFTOKEN=1670033314. The Impact of UML Documentation on Software Maintenance: An Experimental Evaluation, Simula Technical Report 2005-14 and Carleton Technical Report SCE-05-11, Version 2, The economics of software maintenance in the twenty first century, Capers Jones, Chief Scientist Emeritus, Software Productivity Research, Inc. http://www.compaid.com/caiinternet/ezine/capersjones-maintenance.pdf16. Aivosto — Programming Tools for Software Developers, Website, http://www.aivosto.com/project/deadcode.html17. Architectural Modifications to Deployed Software, A.S. Klusener and R. Lammel and C. Verhoef, SIG and Free University of Amsterdam, http://homepages.cwi.nl/~ralf/am/paper.pdf.18. A Case Study on the Long-Term Effects of Software Redocumentation , ICSM, Proceedings of the 20th IEEE International Conference on Software Maintenance, Alexander J. Rostkowycz , Vaclav Rajlich, Andrian Marcus, Wayne State University, Pages: 92 – 101, Year of Publication: 2004 http://portal.acm.org/citation.cfm?id=102142519. Semantic Designs, Website, http://www.semdesigns.com/Products/Clone/20. Finding Bugs is Easy, David Hovemeyer and William Pugh, Dept. of Computer Science, University of Maryland, http://www.cs.nyu.edu/~lharris/papers/findbugsPaper.pdf21. Understanding regression testing techniques, Gaurav Duggal, Mrs. Bharti Suri, Guru Gobind Singh Indraprastha University, Delhi, India. http://www.rimtengg.com/coit2008/proceedings/SW15.pdf22. Software Complexity and Maintenance Costs, Communications of the ACM, Banker et al, November 1993,How to save on software maintenance costs Page 11 of 12
    • http://www.pitt.edu/~ckemerer/CK%20research%20papers/SwComplexityAndMaintena nceCost_BankerDatar93.pdf23. Official ITIL Website, http://www.itil-officialsite.com24. Het legacy probleem aangepakt, H. Vogt & M. Maat, 1998, www.serc.nl25. Een methodische aanpak voor Legacy, H. Vogt, Informatie, September 2004, http://www.omnext.net/downloads/een_methodische_aanpak_voor_legacy.pdf26. Quantitative IT Portfolio Management, C. Verhoef, 2002, Science of Computer Programming (45), http://www.few.vu.nl/~x/ipm/ipm.htmlHow to save on software maintenance costs Page 12 of 12