From Xcore/ecore to OmniGraffle

Some years ago I wrote a small tool for creating OmniGraffle UML diagrams directly from Java source code. Visualizing Java is nice, but since I'm often use ecore/Xcore to define my models, I wanted a tool to also nicely visualize EMF based models.

I have now extended my tool, j2og, to also create UML class diagrams from ecore or Xcore models. Below you see a (manually layouted) version of an automatically generated diagram of the ecore library example.

j2og does not layout the diagram, since OmniGraffle provides some nice layout algorithms anyway. When creating the diagram, you can tweak the output with several settings. For example

1. show or hide attribute and operation compartments
2. show context, optionally grayed out -- the context are classifiers defined in an external package
3. show package names, omit common package prefixes etc.
4. and more

Note that besides OmniGraffle, you can open the diagrams with other tools (Diagrammix, Lucidchart) as well. See the j2og github page for details. You can install the tool via update site or Eclipse marketplace link.

The following image (click to enlarge) is the result of exporting a large Xcore model defining the AST of N4JS, a statically typed version of JavaScript. I have exported it and applied the hierarchy layout algorithm -- no other manual tweaks were applied. Of course, this diagram is probably too large to be really useable, but it is a great start to document (parts) of the model. Well, in case of an AST you probably prefer using an EBNF grammar ;-)

PS: Of course you could use ecoretools to create an UML diagram. I usually need the diagrams for documentation purposes. In that case, OmniGraffle simply is so much better since it is easier to use and the diagrams look so much nicer, (sorry, ecoretools).

Java To OmniGraffle

If you ask developers using Mac OS X about their favorite diagramming tool, you will often get the same answer: OmniGraffle. I also like OmniGraffle very much, and I'm still wondering what makes this tool so much better then all the GEF based editors.

When I have to create diagrams for documenting some Java code, I used to manually draw an UML like class diagram with OmniGraffle. This is an error prone process, and a boring one as well. So, I tried to find a better solution. Since I didn't find any existing tool, I wrote a small Eclipse plugin my self. It automatically generates OmniGraffle class diagrams from existing Java code.

Its usage is very simple: Open or create a drawing in OmniGraffle. Then switch back to Eclipse and select "Create OmniGraffle Diagram" from the context menu of a package in the package explorer, as shown in Figure 1. Configure the output, as shown in Figure 2. The plugin will scan the package and add a class diagram of this package to the front most drawing opened with OmniGraffle. Figure 3 shows the result created by the plugin without any manual changes. It is a visualization of the package "ReverseLookup" of GEF3D.

Fig. 1: Context menu entry

Fig. 2: Configuration Dialog

Fig 3: Created class diagram

At this moment, the plugin can only create class diagrams for a single package. Update: The plugin can create class diagrams for selected types, packages, and sub packages. Besides, the context of selected classes, that is types on which the selected types depend on, can be visualized as well. Attributes are drawn as associations if possible, parameterized collection types are recognized and replaced by 0..* associations. You can configure the output with some switches. Besides filtering members based in their scope, I have added some "filters" I often use when I draw diagrams manually:

• Getter and setters can be omitted
• Methods implementing or overriding methods of interfaces or classes already shown in the diagram can be omitted as well
• In order to better see relations between classes, you can force to draw all associations, even if they would be filtered out by the scope filter.

The newly created shapes are initially drawn using OmniGraffle's hierarchical layout algorithm.

Tip: In order to manually change the diagram, you may want to have a look at my collection of UML shapes at Graffletopia.

You can install the plugin via the update site:

http://jevopi.de/updatesite/de.jevopi.JavaToOmniGraffle

This is an beta alpha version, which will expire 2012. If you find this plugin useful, flattr me! Or leave me a comment below. Depending on the feedback, I will continue developing the plugin -- or not ;-)

In the preferences, you can set the default configuration settings and define the name of your OmniGraffle installation (however, the plugin tries to find the latest installed version automatically).

Last but not least: Of course, this plug is only available on Mac OS X, since OmniGraffle is a native Mac application. The communication between Eclipse and OmniGraffle is done via AppleScript, which is very easy thanks to Peter Friese's blog post.

(At Stackoverflow, someone estimated a tool for creating OmniGraffle diagrams from Eclipse UML2 based models would require 18 months development effort. Well, I needed less then 18 hours. But I only convert Java packages to class diagrams... ;-) ).

Update 2011-11-01:

1. Besides packages, selected types and sub packages can be visualized.
2. The context of visualized types can be visualized. That is, types on which the selected types depend on, such as super classes, can be rendered additionally to the selected classes. These context types are rendered in gray.
3. The default package is now handled as well (see comment by mathpup).