I've been looking for answers about writing functional specifications for a software for a while now but I can't seem to find an answer to my specific case.

I think I understand the difference between technical and functional specs but it's still hard for me to be clear about that when I write those for a RESTful API. To me a RESTful API is a simple bridge between databases and HTTP-based clients to access data in those databases. When it comes to define the functional specs of such an API I can't seem to be correct and to me the only way is to go into details but I know I'm wrong.

When I try not to go into details there are a lot of repetitions like "Accessing [database table here] informations...." or "Modyfing [database table here] informations...." maybe there will be something like "Authenticate client using OAUTH" but that is it. I'm probably missing something here and right now I feel like I'm completely lost when it comes to write such specs about that kind of API.

Is there a specific way to write them when it comes to such an API or is it just me completely misunderstanding the concept of functional specifications?

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    "To me a RESTful API is a simple bridge between databases and HTTP-based clients to access data in those databases." This is where you got it wrong. That would be an API of the database, the API for the application is a whole different thing
    – Javier
    Feb 24, 2015 at 23:56
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    Thank you a lot for your answer. I knew I wasn't really clear about this and now it's obvious. I need to understand the differences between those two. Do you have any suggestions to an article/book about this?
    – Ganitzsh
    Feb 26, 2015 at 10:19

1 Answer 1


For me functional specification of WS is just use case diagram for your backend. You can describe it as set of features like ability to authenticate user, get messages list, finish user's sesion, demand something. Functional specification should describe what (bussiness) services are available through your WS and what is it built for.

  • Ok now it's a bit clearer to me. So if I get what you told me when it comes to write functional specs I need to keep in mind that this is not specific manipulations on data that I need to list but actions that my WS will provide?
    – Ganitzsh
    Feb 26, 2015 at 10:25
  • For me - yes. Functional specification as I understand it is just description (in some form) of what a WS can do for me not how is it done.
    – piotrpo
    Feb 26, 2015 at 10:46

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