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Industry - The Evolution of Information Systems. A Case Study on Document Management


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Paper : The Evolution of Information Systems. A Case Study on Document Management

Authors : Paolo Salvaneschi

Session: Industry Track Session 3: Evolution and migration

Published in: Technology, Business
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Industry - The Evolution of Information Systems. A Case Study on Document Management

  1. 1. 27th IEEE International Conference on Software Maintenance September 25 – 30, 2011 The Evolution of Information SystemsA Case Study on Document Management Paolo Salvaneschi University of Bergamo Faculty of Engineering ICSM 2011 Paolo Salvaneschi 1
  2. 2. Summary• The problem• Aims of the study• The Information System• The study• Results• Validity and Scope• Conclusions and future work ICSM 2011 Paolo Salvaneschi 2
  3. 3. The problem• The management of knowledge required to support the evolution of large information systems• A well-known and difficult problem for IT departments of organizations• Many existing applications evolving for a long period of time (e.g. 10 years).• New projects : - a change of one or more applications ( evolution step) - or the development of a new application ICSM 2011 Paolo Salvaneschi 3
  4. 4. The problem• Although the initial development was based on the best Software Engineering practices, the delivered documents become quickly outdated and no longer useful• The cost of maintaining them during the evolution phase is too high.• Analysts and programmers do not have time to update the documents• Turnover causes loss of knowledge ICSM 2011 Paolo Salvaneschi 4
  5. 5. Aims of the study• To verify a set of hypotheses - The evolution can be supported by a minimal set of “good enough” documents - The set of evolution documents derives from a selections of contents of the development documents - It is based on a cost-benefit analysis• To define an engineering guideline (types and patterns of documents)• To develop a tool for managing the documents ICSM 2011 Paolo Salvaneschi 5
  6. 6. Aims of the study• Minimal set of “good enough” documents - Knowledge is a property emerging from a system composed by analysts/programmers and documents - Documents do not require being “complete” It is sufficient that they be “good enough” - The analysts/programmers may use a minimal set of document as a “landscape” for understanding where to read the details in the code Reference: the theory of minimalist instruction founded in the psychology of learning and problem solving [Carroll, J. M. 1990] ICSM 2011 Paolo Salvaneschi 6
  7. 7. Aims of the study• Questions - Are the actors involved in the evolution able to identify a minimal set (based on a cost-benefit analysis) of evolution documents they consider important to understand the software to be changed? - What is the content of these documents? - What is the relationship between these evolution documents and the development documents? - Are there recurrent sets of evolution documents for classes of applications? ICSM 2011 Paolo Salvaneschi 7
  8. 8. The Information System• The information system of a large retail company - 100 stores in Italy, 2 billion Euro turnover, more than 8000 employees (year end 2009) - IT department: 70 employees,150 servers, 4000 clients, about 100 software applications, 5000 users. - Internally developed software (external suppliers) and tailored market-available packages - AS400 and Web-based environments ICSM 2011 Paolo Salvaneschi 8
  9. 9. The study• 21 interviewed people (analysts/programmers, project managers and system managers) and an external consultant having the role of researcher• 89 applications• About 400.000 Java-JSP LOC, about 1.100.000 RPG LOC and tailored COTS ICSM 2011 Paolo Salvaneschi 9
  10. 10. The studyNumber, role and experience of interviewed people ICSM 2011 Paolo Salvaneschi 10
  11. 11. The studyApplications classified by technologySoftware applications classified by evolution life ICSM 2011 Paolo Salvaneschi 11
  12. 12. The study• Information sources: - Development document stored on a project basis into a database under version control - Applications owners• We study the documents that can help the analyst/programmer to understand the code during software evolution• We do not examine the source code ICSM 2011 Paolo Salvaneschi 12
  13. 13. The study• Meetings between the researcher and each application owner - The researcher explains the hypotheses and requests the application owner to identify a minimum set of evolution documents• An evolution document may be: - A development document stored in the database - A part of a development document (a document whose quality is poor may require a re-documentation process) ICSM 2011 Paolo Salvaneschi 13
  14. 14. The study• Result: a set of candidate documents• Selection through a cost benefit analysisSelection rule ICSM 2011 Paolo Salvaneschi 14
  15. 15. The study• Rcost Cost spent by the new analyst/programmer for reconstructing the content of the evolution document, when needed, from code, data structures and program behavior• Mcost Maintenance cost of the evolution document, estimated by the number of pages Low < 5 pages Medium 5 to 10 pages High > 10 pages ICSM 2011 Paolo Salvaneschi 15
  16. 16. The study• Example 1: - Specification document : a detailed specification of interactive screens. - The reconstruction cost is low: the programmer may run the product and use the person machine interface as a living specification for understanding code - discard ICSM 2011 Paolo Salvaneschi 16
  17. 17. The study• Example 2: - Design document : includes a five-page model of software architecture - The maintenance cost is low - The cost of understanding and reconstructing the architecture from code is high - select ICSM 2011 Paolo Salvaneschi 17
  18. 18. The study• Example 3: - The design document includes a detailed specification (a dozen pages) of an algorithm implementing a set of very complex business rules - The reconstruction cost is high - Also the maintenance cost is high - The owner notes that it is very difficult to understand the algorithm by reading code. - After a discussion: select ICSM 2011 Paolo Salvaneschi 18
  19. 19. Results• Example: the application "Supply Chain" Development documents Evolution Documents The minimal setThe E-R model of the central RDBMS is not considered ICSM 2011 Paolo Salvaneschi 19
  20. 20. Results• The minimalist approach: an average reduction factor of 10 (number of pages of development documents / number of pages of evolution documents)• Types of evolution documents: - Landscapes (e.g. Software architecture) - Aspects (e.g. Use case) - Critical points (e.g. Complex algorithm) ICSM 2011 Paolo Salvaneschi 20
  21. 21. Results• Development documents vs evolution documents - Some contents of the development documents have been discarded or significantly downsized - The development documents tend to be complete and layered according to abstraction levels. The evolution documents include only the most important information and collect parts of the development documents at very different levels of abstraction ICSM 2011 Paolo Salvaneschi 21
  22. 22. Results• From the analysis of the meeting reports: Patterns of evolution documents ICSM 2011 Paolo Salvaneschi 22
  23. 23. Results• Classes of applications ICSM 2011 Paolo Salvaneschi 23
  24. 24. Results• Types of documents• Content of each type ICSM 2011 Paolo Salvaneschi 24
  25. 25. Results• The wiki tool - MediaWiki environment - Now in service - Loaded with all the 89 applications examined in the study - 500 pages and links to three data models generated by an external CASE - 60 registered users - A standard process to upgrade the wiki at the end of each development step ICSM 2011 Paolo Salvaneschi 25
  26. 26. ResultsICSM 2011 Paolo Salvaneschi 26
  27. 27. Validity and Scope• Threats of validity• Representativeness of the results - People and applications biased by specific skills or technologies - Owners with different roles and experience. Applications covering different technologies and development /acquisition processes• Reliability of classification - Subjective assignment of RCost and MCost. - Reduced using an evaluation based on the number of pages ICSM 2011 Paolo Salvaneschi 27
  28. 28. Validity and Scope• Scope• Study related to just one information system Generalization of the results to other information systems should be done with caution• A contribution that can be replicated on other information systems ICSM 2011 Paolo Salvaneschi 28
  29. 29. Validity and Scope• Scope• The study may be generalized to other commercial information systems? - The studied information system is representative of many others commercial systems - The types and patterns of evolution document do not depend on specific technologies or business processes They essentially depend on: The architectural characterization of the application The degree of transparency (in house developed vs COTS) ICSM 2011 Paolo Salvaneschi 29
  30. 30. Conclusions and future work• The study questions have been positively answered• The guideline and the tool are used in the specific information system• Replicate the study for other commercial systems• Other types of systems? ICSM 2011 Paolo Salvaneschi 30