JGraLab4Eclipse

This is an Eclipse project to deploy JGraLab as an Eclipse plugin.

Setup

1. Create a symlink src pointing to jgralab's src folder.

2. Create a symlink lib pointing to jgralab's lib folder.

3. Create a symlink META-INF pointing to jgralab's META-INF folder.

4. Import this project into Eclipse.

5. Make sure that the original jgralab project is not in your workspace. It can be, but must be closed! Otherwise, you will end up with the META-INF folder being detected twice and the plugin appears redundantly in the run configuration. The result may be further issues, such as Activator class not being found.

Note, that if you change any java files, those are actually changed inside your jgralab working copy, so you have to commit them there.

To use the JGraLab plugin, you simply define a plugin dependency in your project.

Using JGraLab Compiled Schemas as Eclipse Plugin

When you try to use compiled TGraph schemas (i.e. schemas where the JGraLab code generator has produced Java files) as an Eclipse plugin, you may experience class loading exceptions. JGraLab throws exceptions java.lang.ClassNotFoundException when trying to load your schema classes.

The reason is that JGraLab accesses schema classes at runtime by Java reflection mechanisms. However, Eclipse installs a separate class loader per plugin. By default, this plugin class loader can not access classes of other plugins.

To handle situations like this, Eclipse has the so-called buddy class loading mechanism. To enable this mechanism, JGraLab's MANIFEST.MF contains a buddy policy:

Eclipse-BuddyPolicy: registered

This means that the class loader of the JGraLab plugin can ask registered buddies for assistance to load a class that it can not find itself.

Registering your plugin as a buddy

To register as a JGraLab buddy, you have to put

Eclipse-RegisterBuddy: de.uni_koblenz.jgralab

into the MANIFEST.MF of your plugin (i.e. the one that contains the generated schema classes). The bundle name used in the buddy registration is the ID of the JGraLab plugin.

This way, JGraLab can find the schema class files, and the class loading exceptions are gone :-)

License

Copyright (C) 2006-2014 The JGraLab Team [email protected]

Distributed under the General Public License (Version 3), with the following additional grant:

Additional permission under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or combining it
with Eclipse (or a modified version of that program or an Eclipse plugin),
containing parts covered by the terms of the Eclipse Public License (EPL),
the licensors of this Program grant you additional permission to convey the
resulting work.  Corresponding Source for a non-source form of such a
combination shall include the source code for the parts of JGraLab used as
well as that of the covered work.