UML based Web Modelling: model the login process?

Question

I am trying to model a web site project with UML. My question: in Use Case and Activity diagrams, should I model the login process (and if so, how)? Looking around, I didn't find a consistent answer to this question. Some people say we should no show the login as any part of the system, neither in Use Case nor in Activity diagrams; some people say we should. Can anyone shed some light on me?

Answer 1

You are right, there is unfortunately no commonly agreed upon or standardized way to model web sites and applications with UML. There is a plentitude of approaches with varying impact, from the early Jim Conallen with Building Web Applications with UML over WebML to UWE, as none of them can be considered authoritative, your best bet in deciding this question is to:

a) Look at as many of these approaches as possible and settle with what the mayority does *, and...

b) ...use some common sense.

One hint for each a) and b) from me:

a) There is a nice example of an UWE UML model here. This example does model the login process.

b) The login process is quite an important part of usage and activity on a site (say you have different content depending of if you are logged in or not, you might login with an 3rd site auth provider like OpenID, ...). if you don't model that - what will you model then? I think the people saying you should not model it do so mostly because they use notations that are not powerful enough, or they just don't know how to use them.

This, I guess, amounts to my advice: do model the login process.

Good luck!

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* Provided you can still find them - some of them seem to be quite short lived

Answer 2

Absolutely. Do model the login process. First of all, it usually contains complex logic (validation, password recovery) that you can't afford to leave not modelled. Secondly, who says it's not a part of the system? It may not be a part of the problem domain, but it is definitely a part of the solution domain.