Why a Rewrite?

Rewriting a large, working application is not something to be undertaken lightly. It is a lot of work & the payback at this stage isn't clear.

It is being done to address some real problems with the the old Sahana codebase:

• Sahana was developed in a custom PHP framework based on design principles which have since become sub-optimal due to the emergence of new MVC frameworks & highly-interactive Web 2.0 UIs.

• The old codebase has grown organically since it was originally designed - standards have broken down & the code is becoming harder to maintain.

• It is currently hard to access data from modules via consistent methods...this is required for serious integration e.g. in GIS & Messaging.

• Using a framework reduces our maintenance overheads & allows us to focus on the user-facing application:
  • ​http://www.youtube.com/watch?v=1J91Ownq-7g

• PHP is not a good language for building large, maintainable applications: ​http://www.ukuug.org/events/linux2002/papers/html/php/index.html
  • especially when using it to write out complex Javascript (the syntaxes are always tripping you up)
  • doesn't enforce Object Orientation
  • poor separation of Presentation & Code

• Whilst there is a fairly coherent custom framework, it isn't adhered to consistently - different developers have done very different things in different modules

• The Javascript components, especially, are very varied with lots of manual AJAX & the use of several different libraries
  • using a modern library means no issues with browser incompatibilities
  • consistency means less headers for clients to download

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