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Developing UML Diagrams for EJBs with Poseidon
by Deepak Vohra
The Unified Modeling Language (UML) is widely used to model enterprise applications implemented by the Enterprise Java Bean (EJB) architecture. The UML profile for EJB specification (also called the UML/EJB Mapping Specification) enables you to map your application from the UML to the EJB. UML representations of EJB elements are specified in the mapping. The specification also defines several stereotypes, which are UML extensions representing the different components (classes, interfaces, fields, and methods) of an EJB. Developing UML diagrams for EJBs provides a preview of your EJBs without actually having to create the EJBs. This allows you to fine-tune your UML model for an EJB before you spend the time developing the EJB. This just saves you time.
In this article, you'll model an example EJB in UML class diagrams. First, you'll learn a bit more about the UML for EJB specification. You'll be using Poseidon for UML as the UML modeling tool to develop the UML diagrams for the EJB, but you can certainly use another UML modeling tool if you'd like. You'll be creating UML diagrams to model the example EJB based on the UML/EJB mapping specification. For more in-depth information on the EJB spec, refer to the J2EE 1.4 tutorial.
Overview of the UML/EJB Mapping Specification
An EJB may be represented by the any of the various views provided by the UML for EJB specification. The UML profile for EJB provides the following views to model an EJB:
- The Analysis View: This represents the structure of an EJB, including the CMP fields and methods in the EJB. An Analysis view does not represent the different interfaces of an EJB.
- The External View: This represents the client's view of an EJB. In the external view, an EJB is modeled as UML classes representing EJB home and remote interfaces.
- The Internal View: This represents the developer's view of an EJB. In the internal view the composition of an EJB is shown including the implementation of the EJB.
- The Implementation View: The implementation view consists of component diagrams which represent the different components of an EJB application, such as Java class files, deployment descriptors and EJB-JAR files.
You'll be creating class diagrams to represent the Analysis, External, and Internal View Details of an example EJB. But first, you need to know how to create a UML diagram in Poseidon for UML. If you are already using another UML modeling tool, and are familiar with the procedure to create UML diagrams, skip the next section.
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