Functional Specifications

 

I'm researching Functional Specs.

 

As usual, Wikipedia has a good overview with lots of good links:

http://en.wikipedia.org/wiki/Functional_specification

 

Excerpts:

"A functional specification does not define the inner workings of the proposed system; it does not include the specification how the system function will be implemented. Instead, it focuses on what various outside agents (people using the program, computer peripherals, or other computers, for example) might "observe" when interacting with the system."

 

And:

"In practice, most successful specifications are written to understand and fine-tune applications that were already well-developed"

My main source of good information is Joel Spolsky (again).

Painless Functional Specifications:

• Part 1: Why Bother
  
• Part 2: What's a Spec?
• Part 3: But... How?
• Part 4: Tips

My take-away?

Functional specs should be easy to read, evolutionary documents that help you think through the design and workflow of your intended application.

Development should not start while there are open issues.

On the other hand, the document should not be considerd 'done' until the project is feature complete.