Using Profiles: a Case Study

To illustrate the concept of profile, you are going to build an extension for an OOM that will let you design a robustness diagram.

The robustness diagram is used to get across the gap between what the system has to do, and how it is actually going to accomplish this task. In the UML analysis, the robustness diagram is between use case and sequence diagram analysis. It allows you to verify that the use case is correct and that you have not specified a system behavior that is unreasonable given the sets of objects you have. The robustness diagram also enables to verify if no object is missing in the model.

You will follow this case study to create a new extension file, which will replicate Robustness.XEM, delivered by default and located in the \Resource Files\Extended Model Definitions folder of the PowerDesigner installation directory.

• Scenario
  You are going to build the robustness extension file starting from a concrete example. The following use case represents a very basic Web transaction: a customer wants to know the value of his stocks in order to decide to sell or not. He sends a stock value query from his Internet Browser. The query is transferred from the browser to the database server via the application server.
• Attaching a New Extension to the Model
  In your workspace, you already have created an OOM with a use case diagram containing an actor and 3 use cases.
• Create Object Stereotypes
  The robustness analysis classifies objects in three categories: Boundary, Entity, and Control.
• Define Custom Symbols for Stereotypes
  You are going to define a custom symbol for UMLObjects related to the Boundary, Control, or Entity stereotypes. The Custom Symbol feature lets you apply the standard robustness graphics into your communication diagram.
• Create Instance Links and Messages Between Objects
  You are going to create instance links between objects to express the collaboration between objects:
• Create Custom Checks on Instance Links
  The robustness analysis implies some behavioral rules between objects. For example, an actor should always communicate with a boundary object (an interface), entity objects should always communicate with control objects, and so on. To represent these constraints, you are going to define custom checks on the instance links.
• Generate a Textual Description of Messages
  You are going to generate a textual description of the messages existing in the communication diagram. The description should provide for each diagram in the model, the name of the message sender, the name of the message and the name of the receiver.