2IS99 Capita Selecta Software Engineering and Technology

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2IS99 Capita Selecta Software Engineering and
Technology
Software Evolution
Mark van den BrandAlexander Serebrenik
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2IS99 Capita Selecta Software Engineering and
Technology

• 5 ECTS, i.e, 140 hours
• Classes
• Friday, 1530 1715 (7th 8th hours).
• Alternative time slots
• Wednesday 1330 1515 (5th 6th hours).
• Thursday 845 1030 (1st 2nd hours)
• 14 meetings (28 hours) self study (112 hours).

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software evolution
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Assignments

• Software Evolution by Tom Mens and Serge
  Demeyer
• Presentation 1 (theory)
• A chapter from the book
• Mail us your choice!
• Presentation 2 (practice)
• Install a tool from, or similar to those from
  your chapter.
• Apply the tool to a case (at least one)
• Report on the application results
• What can you say about the tool?
• What can you say about the case?
• Paper theory practice

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Software Evolution. In the beginning.

• Royce 1970, Waterfall model.

Maintenance bug fixes and minor adjustments
What are the main shortcomings of this model, in
your opinion?
NB Still in use anno 2009!
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1974. Lehmans laws.

• E-type system
• Systems operate in the real world (or address it)
• They should be evolved since the real world
  evolves!
• Evolution laws
• E-type systems must be continually adapted else
  they become progressively less satisfactory.
• As an E-type system evolves its complexity
  increases unless work is done to maintain or
  reduce it.
• The quality of E-type systems will appear to be
  declining unless they are rigorously maintained
  and adapted to operational environment changes.
• There are more

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Macro look Bennett and Rajlich (2000)
architecture decay
Loss of architectural integrity
Patches too costly?

• Legacy system the system that is still valuable
  despite its degraded quality.
• Migration keep functionality, improve quality!
• At what stage would you like to plan migration?

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Micro look Yau et al. (1978)

• Evolution stage of the Bennett-Rajlich model
• Refactoring keep functionality, improve
  structure!
• What is the difference between refactoring and
  restructuring as defined in the Yau model?

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Going extreme

• Software evolution (iterative, incremental)
• short time periods
  
• high degree of collaboration
  
• explicit accommodation of changing needs
• agile software development
• Extreme programming is an example of agile.

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Software Evolution Definition

• Look at the discussion so far.
• How would you define software evolution?
• Software evolution is the set of activities, both
  technical and managerial, that ensures that
  software continues to meet organisational and
  business objectives in a cost effective way.

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Where do we start?

• Versioning repositories (CVS, SVN, )
• Software but what about models, requirements,
  etc?
• Bug tracking systems
• Change logs
• Documentation
• Mailing list archives
• Huge amount of information
• Tooling is essential!

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Research Themes in Software Evolution Science

• What is the nature of software evolution?
• Lehmans law
• Evolution a multi-loop, multi-level and
  multi-agent feedback system
• Understanding the evolution requires
  understanding
• Human psychology
• Social interaction
• Organizational aspects
• Economics and management
• Legislation

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Research Themes in Software Engineering
Engineering

• Technology, means and tools to direct, implement
  and control software evolution.
• Some relevant questions
• What artefacts evolve?
• Requirements, design, code, tests,
• What can we learn from evolution so far?
• Quality change
• How evolvable are our artefacts?
• How can we make them more evolvable?
• Migration, reverse engineering and reengineering
• How is the evaluation implemented?
• Refactoring, architecture transformations

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What does evolve?
Requirements evolution
Design (architecture) evolution. Chapter 10
Data, code, documents, technology evolution
Evolution of different artefacts should be
consistent. This is called the co-evolution
problem.
Tests and proofs evolution Ch. 8
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Consistency and co-evolution Points of discussion

• What should co-evolve?
• Code and database table definitions
• Code and design documentation
• Code and tests
• What constitutes inconsistency?
• How to detect inconsistencies?
• How to ensure absence of inconsistencies?

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What can we learn from the evolution so far?

• What modules are stable?
• How to predict bugs from history?
• How to detect the architecture decay?
• What can we say about the project organisation?
• Is there a major developer? (risk if she leaves)
• Is there correlation between bugs, productivity
  and certain developers/teams?
• Chapters 3-4
• Analysing Software Repositories to Understand
  Software Evolution by DAmbros, Gall, Lanza,
  Pinzger
• Predicting Bugs from History by Zimmermann,
  Nagappan, Zeller

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How evolvable are our artefacts?

• Resilience to change caused by
• Bad readability
• Bad structure
• Code clones (see next slide)
• High complexity
• Insufficient abstractness (OO)
• How to detect these situations?
• Metrics
• Dependencies

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Special technique Code clones elimination

• Presence of code clones impedes evolution.
• Why?
• Points of discussion
• When A and B can be considered clones?
• Identical
• Up to variable/constant/number renaming
• Allowing gaps/repetitions
• How to detect clones?
• Chapter 2 in the book
• Identifying and Removing Software Clones by
  Koschke

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How to make the artefacts more evolvable?
Analysis
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How to make the artefacts more evolvable?
Analysis
Reverse engineering
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How to make the artefacts more evolvable?
Analysis
Reverse engineering
Restructuring, model evolution
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How to make the artefacts more evolvable?
Analysis
Reverse engineering
Restructuring, model evolution
Forward engineering
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How to make the artefacts more evolvable?
Analysis
Reverse engineering
Restructuring, model evolution
Forward engineering
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Special kind of software Legacy

• Chapters 5-7 in our book
• Object-Oriented Reengineering by Demeyer
• Migration of Legacy Information Systems by
  Hainaut, Cleve, Henrard and Hick
• Architectural Transformations From Legacy to
  Three-Tier and Services by Heckel, Correia,
  Matos, El-Ramly, Koutsoukos and Andrade.

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Special kinds of software

• Chapter 9
• Evolution Issues in Aspect-Oriented Programming
  by Mens, Tourwé
• Chapter 11
• Empirical Studies of Open Source Software by
  Fernandez-Ramil, Lozano, Wermelinger, Capiluppi

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How is the evolution implemented?

• Design
• Architecture (model) transformations
• Chapter 7 Architectural Transformations From
  Legacy to Three-Tier and Services by Heckel,
  Correia, Matos, El-Ramly, Koutsoukos and Andrade.
• Code
• Refactoring
• Give an example of a model transformation.
• Do you know any languages allowing to describe
  model transformations?

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Software Evolution _at_ TU/e

• What does evolve?
• Repositories for models Zvezdan Protic, MvdB
• What can we learn from evolution so far?
• Statistical approaches Serguei Roubtsov, AS,
  MvdB
• How evolvable are our systems?
• SQuAVisiT Serguei Roubtsov, Martin vd Vlist,
  Peter Schachtschabel
• How to make the artefacts more evolvable?
• Reverse engineering Dennie van Zeeland, MvdB,
  AS
• How is the evolution implemented?
• Model transformations Marcel van Amstel, Luc
  Engelen, MvdB
• Migration coordination Erik de Vink, Suzana
  Andova

and also YOU!
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Questions?
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Giving presentations, writing papers
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Always keep in mind
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Audience and Purpose

• Audience
• Your audience are your fellow students.
• Neither underestimate nor overestimate them.
• Purpose
• Convince?
• Inform?
• Entertain?

Audience/Purpose Organization Style Flow
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Organization

• What do you remember of a song?
• Identify the kern idea and repeat it
• Oral Keep in mind attention span!

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Style Vocabulary shift

• We got encouraging results.
• The economic outlook is mighty nice.
• The results of a lot of projects have been pretty
  good.
• NB Users, programmers, and other humans in
  academic texts are usually feminine.

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Style Formal Grammar (1)
Written

• Avoid contractions
• wont ? will not
• Appropriate negative forms
• didnt yield any new results ? yielded no new
  results
• Limit the use of run on expressions
• robots, CD players, etc. ? robots, CD players and
  other electronic devices.

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Style Formal Grammar (2)
Written

• Limit the use of direct questions
• What can be done to ?
• We need to consider what can be done to
• Place adverbs within the verbs
• Then the solution can be discarded.
• The solution can then be discarded.

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Style To be or not to be?
Written

• Avoid as much as possible
• The goal of our project is
• Our project aims at
• Crime was increasing rapidly and the police were
  becoming concerned.
• The rapid increase in crime was causing concern
  among the police.

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Flow

• Progress or structure indicator?
• 4-steps scheme
• What shall I do?
• Why shall I do it?
• Do it
• What have I done?

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Flow
Written

• It, this, that
• Teachers know that students need to understand
  the differences between formal and informal
  language. It cannot usually be acquired quickly.
• It this understanding
• Linking words
• however, furthermore, while, for instance,

Audience/Purpose Organization Style Flow
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Presentation

• Long sentences that one cannot even understand
  without rereading them at least twice, and
  blah-blah-blah
• 1 picture 1000 words?

Audience/Purpose Organization Style Flow
Presentation
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Presentation check!
Written

• Format
• Paragraphs? Line spacing?
• Grammar
• Subject/verb agreement?
• Parallel structures agreement?
• About these broken sentences.
• Spelling
• Spell-checker
• Did the spell-checker miss anything?

Audience/Purpose Organization Style Flow
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Bibliography
Written

• Articles Authors, Title, Journal,
  Volume(Number)PageFrom-PageTill, Year.
• Papers Authors, Title, In Editors, eds.
  Conference, Place, ltvolume Vol of Lecture Notes
  in Computer Sciencegt, PageFrom-PageTill, Year.

Audience/Purpose Organization Style Flow
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Bibliography
Written

• Internet Try to avoid
• URI date visited.
• Names
• J. Smith, Smith, J., Jane Smith ?
• Dutch van Dale before Deckers
• Check BibTeX style files for inspiration!

Audience/Purpose Organization Style Flow
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Questions?