Connallen breaking the rules? -UML for Web-

[fluxtah]

Hiya,

After reading up on Use Cases, looking past CRUD, I realise now that Jim Conallen, Author of Building Web Applications with UML actually Refers to system operations in his Use Case.

Can someone confirm that this is acceptable within the domain of a web application, or would it be wise to stick to the tried and tested guidelines?

I appreciate his work, but his Use Case goes against what I have been discussing recently in the 'to split or not to split post' - http://www.sparxsystems.com.au/cgi-bin/yabb/YaBB.cgi?board=UMLPRO;action=display;num=1076246030

- Fluxtah

[sargasso]

Fluxtah,

I have not read his book, but having seen other works by the gentleman I would venture to say that his views are taken more from the "designer" point rather than the "analyst".  

That is, I would expect that he is not looking at use cases as a means to synthesize a structured business view from which to derive requirements and then move into a design phase.  His works tend to "presume" that the requirements have been done and a solution architecture (usually ASP :-) ) has been decided.  Thuis his use of use cases is as a framework to hang design components on.

In thses situations, (requirements and architecture already decided), we too just use the use cases as a scaffold to hang the design around.  We tend to try and pitch it more at the business level then he does, so that we can handle system testing and deployment in the same framework.

Remember, UML is a "simple but rich" notation that lets the audience all talk the same lanuage about the system.  Therefore, if you are primarliy concerned with explaining the design and implementation of web applications and your audience is intended to be the technical developers of those applications then it is acceptable, I suppose, to use use cases in such a manner.

I also note that given a "stateless" architecture such as web applications, the use cases may indeed be closer to a CRUD model than most stateful systems.

[fluxtah]

Cool I think I understand   He does mention that he models within the domain of web apps, so this means that the client might already know the web lingo available.

I have just got another book that called Practical Software Engineering - Analysis and Design for the .NET Platform which shows how to build a web app from start to end using RUP, they also seem to have CRUD related Use Case, though I really do think it might not be necessary depending.

Thanks for the help! :]

- Fluxtah

[mchiuminatto]

Hi

Maybe he's talking about Use Case Realisations (UCR), which are the bridge between use case and the design model (see collaborations in EA). As you can see in RUP literature an UCR have a shape like Use Cases (but dotted border). As far as I know a Use Case can be realised by one or more UCR's.  The UCR are related to Design and Implementation aspects. I Haven't read the book, I'd appreciate if you can confirm if he's talking about UCR's or not.

Regards

Marcello

[fluxtah]

Hiya nope he is not talking about UCR, It appears (after reading other WAE-UML related books) That
within the web world you can call Use Cases anything related to the domain, ie:-

Update Account, Create Account are both valid Use Cases as the Client's we work with often know the lingo and talk to us in this manner.

The language of a Use Case is supposed to be that of the Stakeholders, which in most cases with the web it is, most web dev is based on existing web systems such as Linux & PHP set up or, IIS and .NET, etc.

regards

Fluxtah

[thomaskilian]

IMHO that's what boundaries are good for. They tell in which scope you are thinking, talking, expressing yourself. If you're talking in business terms, you need the additional abstraction layer of UCR.
I always had (and still have little) trouble in putting the right abstraction level (boundaries). Starting from activities over to use cases, business use cases, business processes and use case realization. Unfortunately UML is only clear in what model elements to use, not where and in which condition   But I guess this is simply impossible.

Cheers, Thomas