Rational Software Architect – Java to UML Transformations

Over the past few weeks I’ve been evaluating IBM’s Rational Software Architect (RSA) for WebSphere 7.5 . Whilst RSA is an incredibly powerful piece of software, there are a number of features that are conspicuous by their absence. Perhaps the most prominent of these is the inability of the Java to UML transformation to generate relationships other than Generalisation or Realisation. For example, it won’t generate Association or Usage elements. This makes it pretty useless when it comes to visualising the structure of existing code

You could argue that RSA’s raison d’etre is not the reverse engineering of UML models from Java code, but rather the architecture and development of new applications. This is true, but it misses the point as a number of RSA’s design contract management protocols (notably, "Reconciled Modelling" and "Conceptual Models Drive Development") rely on the reverse transformation of Java code.

According to Rational Support this issue has been logged as a request for enhancement, but when or if it makes it into a future release is anyone’s guess. In the meantime here’s an illustration of the problem.

Step 1 – Create a simple UML model with a composite aggregation navigable from both ends

Figure 1. Class diagram view

Class Diagram 1

Figure 2. Project explorer view

Model 1

Step 2 – Run a reconciled UML to Java transformation on the model

This produces the following java classes (minus the auto-generated comments):

Whole.java

package uml;

import java.util.Set;

public class Whole {

	private Set part;
}

Part.java

package uml;

public class Part {

	private Whole whole;
}

Step 3 – Comment out both private fields in the generated source and run the reverse transformation

As you’d expect, the composite aggregation relationship has now been deleted from the model.

Figure 3. Class diagram view

Class Diagram 2

Figure 4. Project explorer view

Model 2

Step 4 – Uncomment both fields and rerun the reverse transformation

Unfortunately this doesn’t produce the results you’d expect. Rather than explicitly creating an Association element in the UML model, the composite aggregation becomes implicit via the generated attributes for each class. By itself this isn’t a major drama, but it does introduce an inconsistency in your model if you have existing relationships that are modelled explicitly, as was originally the case. To visualise the recreated association you have to filter the attributes to "show as association". However, this only produces uni-directional associations which results in difficult to read diagrams full of unnecessary clutter and noise. The only workaround is to manually recreate the association in the model, which at best wastes time and at worst introduces errors.

Figure 4. Class diagram view (show as attribute)

Class Diagram 3

Figure 4. Class diagram view (show as association)

Class Diagram 4

Figure 5. Project explorer view

Model 3

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Posted in UML

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