Friday, 27 April 2007

QCon 2007 - What I learnt about architecture

This is the first post in a series that summarises what I learnt at QCon 2007.

This post focuses on solution architectures.

For a mind map version, click here QCon 07 Architecture Notes

Inspiration came from the following excellent sessions:

Replacing Amazon's architecture

  • Monolithic application to SOA
  • Took 6 years
  • Cost $2 billion
  • Only 30% of cost delivered visible business value
  • 70% was on the "heavy-lifting"

Architecture relates to

  • how it runs
  • how it fails
  • how its developed
  • how it changes during
    • development time
    • run-time

Architecture is interwoven with the development process

Operational manageability

  • Design for
    • operational configuration
    • operational monitoring
    • failure (no SPOF's)
  • Maintain clear dependencies

Design up-front the parts that are costly to change

  • Reduce the significance of remaining decisions
  • Defer decisions to the last responsible moment
  • Metric is cost of reversing decision
  • e.g.
    • testability
    • security
    • maintainability
    • performance
  • Its like putting stones in a bucket.
stones in buckets

How much up front design (UFD)?

  • BUFD - Big
  • RUFD - Rough
  • NUFD - None
  • Time spent should be inversely proportional to
    • Knowledge of domain
    • Experience in design


  • "A stable architecure is not the same as a frozen architecture"
  • "Doing the simplest thing that works is not same as doing the easiest thing"

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