Model-management approaches

A key difference between Rational® XDE and the new Rational UML modeling products is model management. In the Rational UML modeling products, models are always stored within a single model file; the XDE model and its subunits are merged into one file.

Before you learn more about the new model-management capabilities, it is important to review how subunits work within XDE.

XDE subunits

In order to share parts of an XDE model with multiple users, or to simply reduce the size of a single model file, you can break up a model into individual chunks, commonly referred to as subunits. Subunits help you manage a model by dividing it up and breaking it into smaller, more manageable sections. It is very common for software development teams to work in parallel by sharing out and placing subunits in a configuration management system such as IBM® Rational ClearCase®. Subunits are also important when merging models within XDE; they enable specific model sections to be exclusively accessed.

For example, when you create a subunit from a package (PKX) file, its contents are moved from the model file and stored in the new file. The new file contains the following information:

The original file no longer holds the contents of the package. Instead, the original model file only references the new subunit’s file.

Model management in the Rational UML modeling products

In the new Rational UML modeling products, you manage and control your models at the model level only; the concept of subunits is not carried over from XDE. While the Rational UML modeling products do not use subunits, it does not mean that the information stored in subunits is lost upon import. When you import XDE models, all subunit content is automatically copied into the imported model. The subunit no longer resides as a separate file and is incorporated into a standard, monolithic Rational UML modeling product UML 2.0 model.

The Rational modeling products contain several capabilities that help you divide and manage your imported models.

Once you import your model, you can:

It is important to give your models a logical organizational structure that enables individuals to work independently on specific packages. Correctly organizing the organizational structure of your models will reduce the possibility of model conflicts that must be merged. When you find it necessary to break up a logical model into multiple modeling files, use techniques such as shortcuts, cross-model references, and diagrams to create a logical and hierarchical view of your models.

Related tasks
Preparing for Rational XDE model migration
Migrating XDE models
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