Use case is a document that defines the functionality of the document.
Functional specification is almost perform the same function but some confusion arise.
when u define use case then functional specification need remain or use case is enough?
if functional specification required along with use case then which document develop first?
if not required and u r develop only one document then which is better approach use case or functional specification?
Thanks in advance.
There are more great ideas out then you think...
Per the Rational Unified Process (as I understand it), the requirements are defined via Use Cases along with Supplementary Specifications (which deal with things not easily or logically addressed by use cases). These two deliverables could be combined into one requirements document, but I see no need to re-write the use cases into a separate (non use case) functional specification, assuming (and an important assumption!) that the use cases are being adequately and correctly devised and documented. If there is a perceived need to re-write the use cases into some other format, then that might be begging the question as to whether your requirements analysts are really using use cases correctly?
If you do have to deal with two overlapping requirements sources, then the parties involved will need to determine which takes precedence, and whether both need to be used for test case generation or whether one supercedes the other and is the only document you need to test against. This can only be determined by you and your coworkers/management, based on the realities of your particular situation.