EuGENia: Kick-start your GMF editor development

GMF is a great piece of software in terms of features – and not only because it’s built atop GEF and EMF. Nevertheless, (here it comes) it also requires significant effort to learn, the error messages it produces during validation are often cryptic, the gmfmap wizard typically gets it all wrong, and all put together just make it too hard for the inexperienced user.

To reduce the effort required to build a basic editor we’ve implemented a tool, called EuGENia, which can derive the gmfgraph, gmftool and gmfmap models that are required to generate a fully functional GMF editor using only the ECore metamodel itself, augmented with a few GMF-specific annotations (I know that annotations pollute metamodels but they’re irresistibly convenient).

The Filesystem editor example

In this example we’ll construct a GMF editor for a filesystem metamodel. To generate a basic GMF editor from the metamodel, all we need to know is that:

• The root of the diagram is FileSystem
• File and all of its subclasses (Drive, Folder, Shortcut etc) are nodes with a label that reflects the value of their name attribute
• Shortcut.target is a link
• Sync is also a link class with Sync.source as the one end, Sync.target as the other and lastSync as the label

To capture the above, plus a bit of formatting information, we add the following @gmf.* annotations to the metamodel (in Emfatic):

@namespace(uri="filesystem", prefix="filesystem")
@gmf
package filesystem;

@gmf.diagram
class Filesystem {
    val Drive[*] drives;
    val Sync[*] syncs;
}

class Drive extends Folder {

}

class Folder extends File {
    @gmf.compartment
    val File[*] contents;
}

class Shortcut extends File {
    @gmf.link(target.decoration="arrow", style="dash")
    ref File target;
}

@gmf.link(label="lastSync", source="source",
                 target="target", style="dot", width="2")
class Sync {
    ref File source;
    ref File target;
    attr String lastSync;
}

@gmf.node(label = "name")
class File {
    attr String name;
}

Through the process demonstrated in this screencast EuGENia can generate the following editor without the user needing to touch any of the .gmfgraph, .gmfmap or .gmftool models manually.

Obviously EuGENia doesn’t support all the options the .gmfgraph and .gmfmap models do but only a small subset of commonly needed features. A complete list of the annotations EuGENia supports as well as instructions for obtaining it is available here.

Follow up: EuGENia: Polishing your GMF editor

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