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Requirement Engineering Use Case diagram



At my University I have a module Requirement Engineering.

We have to do UML Use Cases and I understand 99% but I have one question.

I have a Use Case “check password” that is an <> from “login email” and “login Facebook”. Once it is checked on the app itself (login email) and once it is Facebook that checks it (I suppose Facebook is another actor) Can I use the same Use case “check password” or do I need a separate one? or do I just don’t check the password from the “login Facebook” and connect it directly to Facebook. Do I have to do the same for output Error.

I know everything is German sry

I hope someone can help. I have always been lucky here.

Thanks for reading



I guess it’s up to you, there’isnt, to me, a clear cut correct answer.
My take on it is to keep using the “check password” use case you already created, there’s no need to have another one since you’re checking always the same credentials.
Regarding the error reporting you need a new use case since you’re not logging into Facebook but into Spotify (using Facebook credentials) so you need Spotify to throw an error in the app, not Facebook. For example if you change Facebook password and open the Spotify app you need the app to throw and error of incorrect passoword.

Why aren’t you using keys in this diagram? It makes everything more clear. Defines better what data each use case is handling and what data are being passed on.


Hi Janick

I would not suggest separate “check password” use cases, what I would suggest is first having a login use case (user picks email or facebook etc.), then an extension for use email and another for use facebook, then an authenticate function. If you are using facebook, that data would then need to be transmitted (securely) to facebook, if you get an error then display. Something like this:

Also totally can’t read German, but in my mind it is a faux pass to have a system/subject the same name as an actor So you need to review why you have both.

I highly recommend as a site for tips and tricks doing these things :slight_smile:

I hope I’ve helped.

Good luck and have fun.