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

The Evolution of Information Systems

A Case Study on Document Management

27th IEEE International Conference on Software MaintenanceSeptember 25 – 30, 2011

ICSM 2011 Paolo Salvaneschi 1

A Case Study on Document Management

University of BergamoFaculty of Engineering

Paolo Salvaneschi

• The problem

• Aims of the study

• The Information System

• The study

• Results

Summary


• Results

• Validity and Scope

• Conclusions and future work

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

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the initial development was based on the best Software Engineering practices, the delivered documents become quickly outdated and no longer useful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.


evolution phase is too high.

• Analysts and programmers do not have time to update the documents

• Turnover causes loss of knowledge

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


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

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


- 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]

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?


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?

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,


4000 clients, about 100 software applications, 5000 users.

- Internally developed software (external suppliers) and tailored market-available packages

- AS400 and Web-based environments

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


• About 400.000 Java-JSP LOC, about 1.100.000 RPG LOC and tailored COTS

The study

Number, role and experience of interviewed people


The study

Applications classified by technology


Software applications classified by evolution life

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


• We study the documents that can help the analyst/programmer to understand the code during software evolution

• We do not examine the source code

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)

The study

• Result: a set of candidate documents

• Selection through a cost benefit analysis

Selection rule


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


• Mcost Maintenance cost of the evolution document, estimated by the number of pages Low < 5 pages

Medium 5 to 10 pages

High > 10 pages

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


person machine interface as a living specification for understanding code

- discard

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 cost of understanding and reconstructing the architecture from code is high

- select

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


- 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

Results

• Example: the application "Supply Chain"

Developmentdocuments


EvolutionDocumentsThe minimal set

The E-R model of the central RDBMS is not considered

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)

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


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

Results

• From the analysis of the

meeting reports:

Patterns of evolution documents


Results

• Classes of applications


Results

• Types

of documents

• Content

of each type


Results

• The wiki tool

- MediaWiki environment

- Now in service

- Loaded with all the 89 applications examined in the study


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

Results


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


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

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


• A contribution that can be replicated on other information systems

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)

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?

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

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