Which UML diagrams may I need to conceptualize bac

Question

I'm trying to develop a web-app and some desktop apps, all of these apps communicates via database or socket tcp. These desktop apps are running in background so, there is no use cases and the web-app is only used by remote users.

And, these desktop apps communicates with the web-app via the DB and vis versa.

Which UML diagrams may help me to conceptualize the work of the desktop apps, please?

I've tried to conceptualize this thing using the deploiement diagram, but, I think that it's unsufficient to explain the whole work in a report. Isn't it ?

Thanks a lot!

Answer 1

If you read up on the theory of use case diagrams and actors, you will see that an actor (something that interacts with a use case) can be a person or another system.

In this case, since your app is running in the background, is must be triggered by something: by a person or by a job scheduler (=a system). That means that the triggering is done by an actor, since an actor can be a person or another software system.

So that means you have a use-case (your app) and an actor (scheduler or person). In that way your background app can be described as a use case in a use-case diagram, together with the rest of your system.

Answer 2

As Rolf Schorpion told, you can still use use case diagrams with systemic actors. Just make sure that actor is something external to the system (or part of the system). A typical actor can be Timer (if it is time-controlled).

Besides there is a plenty of UML-diagrams you can use. From the short desctiption you posted, I'd recommend the following set of diagrams (at least these are the diagrams I'd asked you to prepare in order to better understand the system you briefly described):

Mandatory:

1. Component diagram - showing structural organization of your system and their dependencies (desktop app, WEB app, DB are components)
2. Deployment diagram - showing the network organization, servers and how the previously defined components are actually deployed on server nodes
3. Sequence diagram(s) - showing the important communication scenarios between the components. You mentiones TCP, so this can be further refined and displayed using one or more sequence diagrams. It there is a standard communication pattern, a single sequence can be enough. Otherwise, several sequences can be used to cover all significant communucation scenaria

Optional:

1. Class diagrams - to specify internal components structure - design (blue print of the source code). I recommend this one only if there is a complex design in each compoennt, worth this effort. If not, it could be costly to keep the model in sync with the actual code.
2. State disgrams - if a class of componen show a behavior that could be modelled as a set of discrete states (e.g. ON, OFF, IN REPAIR, OUT OF ORDER), this diagram is very powerfull and highly recommendedn
3. Activity diagram - if you have some interesting non-trivial algorithms or simply want to show an overall system logic in terms of sequenced tasks, use activita diagrams.

These are the most common UML diagrams. Besides you have a couple of them more that couls be used in some special conditions (timing for example), but I'm sure you can model almost everything using only these. Use case is far from the first choice for UML modelling.

If you have some further questions or doubts, just ask.