What they dont tell you: Software Engineering lessons

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What they dont tell youSoftware Engineering
lessons

• Sriram Srinivasan (Ram)
• sriram_at_malhar.net

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Good design comes from
Experience
Experience
comes from making bad mistakes
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Today, youll learn ..

• To look at methodologies with a critical eye
• What worked for me, and what didnt
• QA practices adopted for a successful commercial
  product
• WebLogic Application Server (www.bea.com)

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OO is wonderful

• Application system of interacting objects
• Guides thinking, partitioning the problem
• RUP provides different views
• Structural view of data, processes
• Class diagrams
• Dynamic view
• Use cases
• Sequence diagrams, State charts
• Focus on data and data flow

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Case Study 1 OO thinking

• One of the worlds largest courier companies
• Project To come up with a company-wide business
  object model
• Re-engineer all systems with this model
• Promote reusability across the enterprise

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Case Study 1 Lessons learnt

• Business objects nebulous concept
• Reusability dubious goal
• Clear problem statement
• Replace a legacy system is not a goal.
• Dont think object, web, computer UML when
  learning a domain
• Systemic thinking includes manual processes

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Case Study 2 Components

• Objects vs components
• Remote objects, Remote components
• CORBA, DCOM, Java RMI
• Enterprise JavaBeans, DCOMMTS, .NET
• My experience, from both sides
• Used remote components for a large aircraft
  scheduling application, network management
  systems
• Wrote a CORBA server
• Wrote the worlds first EJB framework

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Case study 2 Lessons

• Business Object Models do not translate well to
  code
• Mismatch between RDBMS and objects
• Network not transparent
• Duplication between object framework and RDBMS
  concurrency, transactions, security
• Using objects to generate UI bad idea
• All designers must be active programmers

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Other delivery issues

• Customers want cheap, fast, good
• Constant change
• Requirements, technologies, business practices,
  programmers
• Documents and Code mismatched soon
• Proposed solution eXtreme Programming (XP)

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Extreme Programming

• Kent Beck, Ward Cunningham
• Stresses customer satisfaction
• Focus on attitude
• simplicity (in documentation, in coding)
• communication
• feedback
• courage embracing change
• RUP and XP coexist happily

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XP Practices

• Planning
• Writing User Stories (use cases)
• Each story implementable in 3 weeks
• Release and Iteration planning
• Sort stories by desirability
• Designing
• Simple Only accommodate what's needed now, not
  for the future
• Design evolves as project evolves
• Customer available throughout the project

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XP Practices (contd)

• Coding
• Implement and deliver a story at a time
• Write unit tests first
• Dont write more code before exisiting tests
  succeed
• Pair Programming
• Continuous Refactoring, Integration
• Collective ownership
• Testing
• All code must pass unit tests
• All bug fixes accompanied by more tests

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XP pitfalls

• Types of software projects
• Shrinkwrap, embedded, games, throwaway, internal
  IT projects
• Most methodologies apply to internal IT projects
• Customer is not always available
• Not much chance of repeated versions in embedded
  software and games

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XP pitfalls

• Pair programming doesnt work well
• Ego clashes, mismatched experience levels, need
  for unstructured think time
• Pair desigining, debugging works well for me
• Erring on the side of too less documentation,
  less design
• Problem with inexperienced XPers.
• Larger projects require more structure
• Refactoring costs time

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What works for me

• General
• Meeting notes, emails, random ideas, prototypes
  archived and indexed
• Every team project has a web-site
• PowerPoint instead of verbose documents
• Daily short meeting
• Requirements phase
• Problem statement (not list of features)
• Design
• User Interaction first objects later

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What works for me (contd)

• Programming
• Write unit tests first
• Source code control, frequent integrations.
• Assertion checks throughout
• Peer code reviews
• Tools Profiler, Coverage Thread analyzer
• Design docs updated as design changes
• Test for performance
• System Test
• Web test tools
• Post-mortem

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QA _at_ BEA

• www.bea.com
• Weblogic Server
• Market leading Java application server for the
  last seven years
• Testers and programmers in same room
• Several tiers of testing

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Tier 1 Build and Test Monkey

• Fast, basic sanity check of recent checkins
• Build and test in clean-room environment
• Rule by shame
• Monkey spams engineering for build or test
  breakage listing suspects
• Performs broad-spectrum functional test
• (3000 test cases) that should always pass
• Status viewable through intranet
• Tools Inhouse testing framework, WebLogic itself
  used as intranet webserver

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Tier 2 Nightly

• Nightly functional testing (same tools as
  earlier)
• Quarter-million test cases in 12 hours across 5
  codeline branches
• Partial JDK, OS, RDBMS platform matrix coverage
• Daily report to all WLS engineering via web page
• QA folks analyze and summarize report each AM
• Longevity testing
• Web based test tools

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Tier 3 Weekly

• Full functional testing
• Full JDK and platform and protocol coverage
• Full database coverage
• Full 3rd party integration coverage
• Performance testing
• Loadrunner, mercury interactive, grinder
• 30,000 client loadrunner configuration on ES4500,
  E10000
• Stress tests, applications like ecPerf, ePizza,
  PetStore
• Sun J2EE CTS

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Tier 4 Monthly

• Manual GUI testing
• Packaging/download testing
• Installation verification
• Examples testing
• Complexity/coverage analysis
• McCabe software metrics
• Usability testing
• Each bug tracked independently. Bug fix requires
  test case name
• Regression tests

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References

• General
• The Mythical Man Month, Fred Brooks
• About-Face Principles of User Interface design,
  Alan Cooper
• The Inmates Are Running The Asylum, Alan Cooper
• Bringing Design to Software, Terry Winograd
• The Design of Everyday Things, Donald Norman
• Software Engineering
• www.joelonsoftware.com, Joel Spolsky
• www.holub.com, Alan Holub
• www.ObjectMentor.com, Robert Martin
• www.nakedobjects.org

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References

• Extreme Programming
• eXtreme Programming Explained, Kent Beck
• www.extremeprogramming.org
• xprogramming.com
• Extreme Programming Installed
• Ronald Jeffries, Ann Henderson, Chet Hendrickson
• Extreme programming considered harmful
• www.avoca-vsm.com/downloads/downloads.html
• UI
• www.useit.com, Jacob Nielsen
• www.uidesign.net
• www.cooper.com Alan Cooper

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References

• Distributed computing
• A Note on Distributed Computing, Jim Waldo et al
• www.sunlabs.com/techrep/1994/abstract-29.html
• WebLogic Application Server
• www.bea.com