AntiPatterns Tik110'498 Seminar on Design Patterns HUT 18'05'2001 Vesa Krpijoki Softplan Oy

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AntiPatternsTik-110.498 Seminar on Design
PatternsHUT 18.05.2001Vesa KärpijokiSoftplan
Oy
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Introduction

• 5/6 of software projects are regarded as failures
• 1/3 of software projects are canceled
• 50 years of software development
  gt still the same fundamental
  problems are encountered over and over again
• no generic preventive actions for avoiding the
  problems
• no generic countermeasures for mitigating the
  effects of the problems
• Possible solution AntiPatterns?

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Background for AntiPatterns

• AntiPattern is a literary form that describes a
  commonly occurring solution to a problem that
  generates decidedly negative consequences.
• Design Patterns define an ideal solution to a
  problem, while the AntiPatterns describe two
  solutions
• AntiPattern solution the unwanted, problematic,
  existing solution
• refactored solution the good solution (target of
  the AntiPattern)
• Purpose is to give the IT industry a common
  vocabulary and means to discuss and mitigate the
  common problems
• Developed to complement the existing fundamental
  software patterns (GoF, Buschmann, Analysis,
  CORBA)
• AntiPatterns have arisen from the discussion and
  proposals by patterns experts on the Internet (
  1996-)

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AntiPattern Fundamentals (1/2)

• Three groups of AntiPatterns
• Software Development AntiPatterns
• Software Architecture AntiPatterns
• Software Project Management AntiPatterns
• Root causes for AntiPatterns
• haste
• apathy
• narrow-mindedness
• sloth
• avarice
• ignorance
• pride

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AntiPattern Fundamentals (2/2)

• Primal forces management of
• functionality
• performance
• complexity
• change
• IT resources
• technology transfer
• Software Design-Level Model
• Object level
• Micro-architecture level
• Framework level
• Application level
• System level
• Enterprise level
• Global/Industry level

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AntiPattern Template

• Possible templates Pseudo-AntiPattern,
  Mini-AntiPattern and Full AntiPattern template
• Mini-AntiPattern template consists of
• compact, unique and unambiguous name
• description of the AntiPattern solution
• description of the refactored solution
• Full AntiPattern template includes also for
  instance
• scale and scope of the AntiPattern
• root causes practical description of the typical
  causes
• misused primal forces
• symptoms of the problem (negative) consequences
• variation

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Software Development APs

• Concentrates on lowest layer of IT business
  programming, code management and (mis)use of DPs
• Groundwork by Mike Aykroyd in 1996
• Most famous software development APs include
• Blob
• Spaghetti Code
• Cut-and-Paste Programming
• LavaFlow
• Golden Hammer
• Mushroom Management

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Mini AntiPattern Robot

• I believe the power of the holy scripts (TM)!
• Why would you do the two replacements with
  Notepad?? Let me code a script that does it for
  you.
• No, that doesnt need to be reviewed or tested.
  I ran a script that modified all the 4527
  try-catch clauses recursively. It works, I
  guarantee that.
• Problem A person who believes that almost
  anything can (and should) be automated. Often an
  administrator who wants to play in his own
  sandbox.
• Root causes Sloth, Pride
• Refactored solution interaction, mentoring,
  constant peer reviews, pair programming,
  management control

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Mini AntiPattern Lonely Rider

• Oh no we cannot do anything to the module before
  John comes back from his two-month holiday (in
  Bali)!
• I am a guru. Id like to work alone, its just
  my way of doing things.
• I dont know about it. Ask John, he has written
  the code for almost all of our key components.
• Problem A seemingly irreplaceable person who
  intentionally or unintentionally becomes the
  single point of failure and bottleneck in the
  software project
• Root causes Avarice, Pride
• Refactored solution interaction between
  developers, constant peer reviews, competence
  transfer, mentoring help to less experienced and
  busy developers

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Software Architecture APs

• Software architecture focuses on
• Partitioning the system into well-defined modules
• Interfaces between the modules
• Technology applied to implement the interface
  connections
• Well-known architecture APs include
• Stovepipe System
• Cover Your Assets
• Architecture by Implication
• Design by Committee
• Swiss Army Knife
• Reinvent the Wheel

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Project Management APs

• Project management focuses on
• Controlling the software process
• Management of human and IT resources
• Management of external interfaces (customers and
  partners)
• Common project management APs are e.g.
• Analysis Paralysis
• Death by Planning
• Corncob
• Project Mismanagement
• Fire Drill
• Smoke and Mirrors

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Mini AntiPattern Jekyll Hyde

• Mr. Jekyll in private conversation, 801 AM
  (gentle voice) Yes, I think your idea is great,
  lets talk it over in the lunch. Its on me.
• Mr. Hyde in project meeting with the subordinates
  and the big boss is listening, 8.03 AM (furious)
  What the.. Thats a poor idea. And why no one
  has done anything to think about this beforehand?
  I cant stand this kind of incompetence!
• Problem A (typically opportunist) person whose
  behaviour is totally dependent on the audience.
  Jekyll transforms to and from Hyde in a
  nanosecond.
• Root causes Ignorance, Pride
• Refactored solution a good long talk in a proper
  and non-offending environment (pizza?) a
  transfer to other projects departments

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Discussion

• AntiPatterns define a well-known and publicly
  recognized way to identify and prevent the common
  mistakes and problems in software development
• AntiPatterns describe commonly known and tested
  countermeasures to an AntiPattern solution in the
  form of a refactored solution
• AntiPatterns are available for anyone (Internet)
• Also non-software -related AntiPatterns exist
• Anyone can write and propose new AntiPatterns
• AntiPattern must be encountered at least in three
  different occasions (forms) before accepted
  officially