Sequence diagram, some questions

[Marneus]

Hello to all, I'm trying to create my sequence diagram, but some questions.

I'd like to create a sequence like "Fast search" or "Advanced Search" in an alt fragment and then a message wich comes back with the result.

My problem is that I have one activation rectangle for the first message, and then a second for the second message and its result.

I'd like to have only one activation rectangle.

Do you know how?


If my question isn't clear, just tell me

[«Midnight»]

Perhaps you could answer the following question - either in your design or to us readers:

How would your system know which search has been invoked?

If the diagram you are drawing is at a higher level of detail than this, you might simply want to show that a search of either kind, perhaps not specified, is invoked and completes.

If you are working at a lower level of detail you might want to put a condition - what kind and how you express it probably depend on other aspects of your design - on the actions; they could then come from the same activation box, with the conditions giving some idea of how the system determines what to do.

You might also want to consider two diagrams, one for each scenario. This would probably by my preference. You can then tie them to the use cases or fragments thereof - EA provides several mechanisms for this.

HTH,
David

[Marneus]

It's a high level diagram, it's the user who choose wich way to take.
In fact, I want to merge two branches of my use case in one diagram, with a low level of detail.

[«Midnight»]

I'm not quite sure what your second sentence means. If you mean you want to merge the two threads into a single, more detailed diagram, I'd tend to avoid that. But this is only my opinion, it might not work for you.

As I said before, at a high level (little detail but a wide overview of the system) I would probably just show that a search could be invoked, and an answer received. Perhaps adding a UML note to inform the reader that more than one type of search could be used.

I would then provide a more detailed sequence diagram for each case, showing just what happens, and any differences that might be important - as before these could be expressed with additional elements, notes, or whatever (perhaps even UML Frames).

In order for the user, and your developers, to navigate these in a meaningful way, you might want to start with use cases at the same levels of detail. Here you could provide a high level use case for invoking a search, and show alternate scenarios for each type, once again identiying important differences. This allows you to introduce the elements and considerations you will elaborate in the sequence diagrams, and in other dynamic and structural diagrams elsewhere in the model.