# Java Composition Discoverer

Quality disclaimer: this Java Composition discoverer has good test coverage compared to the complexity of the discovery process, and it is based on the Java and KDM Source discoverers, which are well tested.

## Description

MoDisco provides a discoverer associated to the metamodel definition described here.

The discovery takes a workspace Java project as input.

- The first step of the discovery creates one Java model, using the associated discoverer.
- The second step of the discovery creates one Kdm inventory model, using the associated discoverer.
- The third step creates a model with JavaApplication metamodel instances with references to the two leaf models.

## User manual

The plug-in provides the user with a contextual menu to easily create models.

By right-clicking on a Java Project in the Eclipse Package Explorer view and choosing Discovery > Discoverers > Discover Java and Inventory model from Java project you can quickly create the Java Application model of your application:

A discovery parameters dialog opens to let you specify the parameters of the discovery:

See the documentation of the Java discoverer for an explanation of the parameters.

Once launched, a progress dialog will appear as soon as the operation begins. Depending on the size of your application, the reverse engineering process might take some time to complete:

At the end of the process, the newly created model files are added to the root of your project if you set SERIALIZE_TARGET to true:

And the model is opened in the default model browser if you selected Open model in editor after discovery:

A xmi file suffixed by _java2kdm.xmi contains the root element of the model, which refers to the _java.xmi Java model file and the _kdm.xmi Inventory model file.

Some referenced xmi fragment files are serialized into a java2kdmFragments directory (see Resources distribution in the benchmark).

Once the main file _java2kdm.xmi has been opened in the MoDisco model Browser, you may navigate through the JavaApplication metamodel instances to the Java and kdm.source metamodel instances.

Some facets called javaToKdmShortcuts and KdmToJavaShortcuts are available for allowing navigation shortcuts from some Java/Kdm.source model elements. (enabling the "Show Derived Links" option is necessary to view the shorcut links)

To take advantage of memory usage tuning (see the benchmark), for huge Java legacy code, the MoDisco global preferences should have the "resources loading depth" set to 1 (0 works but is less interesting for browsing). This setting allows the lazy loading of xmi fragment files, through the model navigation, for less memory usage than with an initial complete loading of resources.

Using the Group by package setting will ease the selection in the types panel considering the metamodels (EPackages instances) involved.