Chapter 3 Using the PowerDesigner Interface

Using extended dependencies

You can use extended dependencies to specify free collaborations between PowerDesigner objects. These links are allowed among objects of any type of model. They are not interpreted and checked by PowerDesigner as they are meant for documentation purposes only.

You can complement these links by creating stereotypes to specify their meaning. Stereotypes are used to define extended dependencies in all PowerDesigner modules, and appear in the Extended Dependencies tab of each non-link object property sheet. You can type them directly in the Stereotype column or select a value from the list if you have previously defined stereotypes in an extended model definition (.XEM) applied or embedded to the model.

For more information about stereotypes in an extended model definition, see "Working with Extended Model Definitions" in the "Managing Objects" chapter.

Example

The following example illustrates how extended dependencies can help you document relations between package or model objects.

This example about generation from a CDM to two PDMs generated with different DBMS shows that the file object SourceCDM.cdm has extended dependencies with the file objects GeneratedPDM.pdm (for Sybase IQ) and GeneratedPDM2.pdm (for ASA7). These extended dependencies are defined by the <<generation>> stereotype to explain that the two PDM come from the same CDM.

For more information, see the "Using file objects" section in the "Managing Objects" chapter.

Creating an extended dependency

The object from which you create the extended dependency is called dependent object and the object towards which the extended dependency goes is called influent object.

You can create an extended dependency in one of the following ways:

• From the diagram using the Link/Extended Dependency tool from the diagram toolbar. To create an extended dependency graphically you simply have to select Link/Extended Dependency tool in the diagram toolbar and click inside the dependent object and while continuing to hold down the mouse button, drag the cursor to the influent object where you can release the mouse button.
  This method does not work for extended dependency between objects belonging to different types of models as these cannot have symbols in the same diagram.

     Moving extended dependencies
  Extended dependencies behave like oriented links. When you move the dependent object, you also move the extended dependency attached to it. And when you move the influent object, it is replaced with a shortcut to preserve the extended dependency definition.

• In the Extended Dependency tab of the dependent object property sheet. You can use the Add Objects selection dialog box to create an extended dependency with an object belonging to any type of open model. If you select an object that belongs to another package or model, a shortcut is created for this object.

To create an extended dependency from the dependent object property sheet:

1. Double-click a non-link object to open its property sheet and click the Extended Dependencies tab.
2. Click the Add Objects tool to open the Add Objects dialog box.
3. Select a model among open models from the Model box, a package from the list, and an object from one of the sub- tabs.
4. Click OK.
   
   The extended dependency you have created appears simultaneously in the list of extended dependencies but also in the diagram if objects at both extremities are displayed.
5. Click the Stereotype column for the extended dependency you have just created and type a stereotype or select a stereotype from the list if available.
6. Click OK.

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