Is this use case is correct and proper according to uml?

Question

Is This use case is correct/proper according to UML? if not please give some input to improve it..

The ways we can look on it as the boundary value "Use Cases" can be described something as "Release Phase 1"?

Writer Module/Reader Module should be proper Ator?

alt text http://img190.imageshack.us/img190/6708/usecaseh.jpg

Answer 1

This diagram is telling me that there is something external to the system you are developing called a "Writer Module". The Writer needs three Use Cases, for example Initialization.

Similarly another actor needs Check Status and StackUp.

If that is what you intended to say, then this diagram works. Do you really mean it? Does only the Writer module Initialise the system? Or does the system initialise itself? Can the Reader check whether the system has been initialised, before it has been initialised? Is there another Use Case?

Small improvement: make the Use Case names match in their parts of speech. Initialisation is a "Thing", Check Status is an "Action". Perhaps Initialize System might be better? "Stack Up" not "StackUp", be consistent.

Answer 2

Normally the reason you group the use cases using a box is to show what system is helping meet or realize the use case. It is formally known as a system boundry ("The system you are building". Normally the systems, modules, etc that are actors are more black box, existing, or use only. If there are many new or modified systems this definition gets confusing.

The other comments are semantics of what you are showing, but are not sytax, still important.

Page 103 of Martin Fowler has a diagram and discription that uses the system boundry concept and system actors.

Answer 3

To pick on an example: this diagram says that Check Status is a scenario with two participants, a Writer and a Reader. Is that what you want to say?

Also, I don't remember seeing boxes around (sets of) Use Cases in general.

Answer 4

Use cases are meant to show how someone uses a system to get something of value. Actors always represent persons, in the sense of an independent being who has goals and is capable of seeking something of value.

Actors are represented in one of several ways, either directly by name, or by inclusion through a role, or by proxy in the form of an agent acting on behalf of a person or role (the "system" actor). Regardless of the form, the actor is always independent, and always capable of "acting" upon the system to achieve its own ends.

The diagram you have here is NOT a use case diagram. "Modules" are not independent, goal-seeking entities, they appear to be simply components of some system. They are not capable of "seeking" anything, they are just implementation details.

The diagram you are probably looking for is the Deployment diagram (if you want to model how specific components are wired together), the Activity diagram (if you want to model application logic), or the Class diagram (if you want to model the formal relationships between components).