Entities

In this section you will create your first entity using AndroMDA. We will create an entity called Timecard that will represent a timecard in the application. We will associate it with the User object, which will be the person that submitted the timecard. Our finished entity diagram will look like this:

Note that we have marked the Timecard class with a stereotype of Entity. This tells AndroMDA that Timecard is an Entity as opposed to other type of model elements such as Enumeration or EmbeddedValue. Stereotypes determine what pattern of code AndroMDA will generate for a model element. More specifically, they determine which AndroMDA code generation templates will be triggered.

Also nte that we have marked the attributes to be of type Date andString. These are not .NET types, but rather in model driven architecture the model is kept independent of technology and hence all model elements are defined in terms of platform independent types. So Date and String in this context are platform independent types. When we run AndroMDA to generate code, it will translate platform independent types into platform dependent types such as System.String and System.DateTime . If we were to use the same model to generate a Java application, AndroMDA will translate String intojava.lang.String, which is the Java equivalent ofSystem.String. As you can see, a key advantage of the model driven approach is that your investment in the business models is preserved even as technologies come and go.

Now lets add the Timecard entity to the model:

  1. Create a new diagram by right clicking on the Domain package and clicking New Diagram |Class Diagram. Set the name of the diagram to Entity Diagram and clickOk.
  2. Click the Class tool in the toolbar and make a new class on the diagram surface. Double click on the class, name itTimecard, and add the Entity stereotype to it.
  3. Right click on the TimecardVO object and selectInsert new attribute. Add three public attributes to the class by:
    • One called startDate of typeDate.
    • One called comments of typeString.
  4. We now want to relate the the User entity to the Timecard entity. Drag the User class onto the diagram. If it looks very cluttered you can right click on it and selectSymbol Properties. Uncheck the Show Tagged Values option under General and also uncheck Show Attributes Properties in the Attributes section. Finally clickOk, right click on the User class again, and selectAutosize.
  5. Because each user can submit many timecards, we need to create an association that defines this relationship. Click the Association tool and draw an association between the Timecard class and the User class.
  6. Set the association multiplicity to * on the timecard end of the association by right clicking on the association end near the Timecard entity and selecting*.
  7. Set the name of the timecards association endpoint by right clicking on the association end near the Timecard entity and selectEdit name. Name the end+timecards.
  8. Set the association multiplicity to 1 on the user end of the association by right clicking on the association end near the User entity and selecting1.
  9. Set the name of the submitter association endpoint by right clicking on the association end near the User entity and selectEdit name. Name the end+submitter.