Is it possible to use the Presentation Model Pattern for a GEF-based RCP app with an EMF domain model?

Question

I'm working on an eclipse RCP application, using a third-party domain model based on EMF, and a GEF editor for editing.

GEF uses the MVC pattern, which would be fair enough if I didn't have to use a specific layout for drawing the model graph on the editor view. The domain model I am using includes no visual information whatsoever (which in itself is a good idea), but I'd like to be able to assign coordinates to Figures in their EditParts. This would make it much easier for me to calculate the position of the figure in the layout.

Now I have stumbled upon the Presentation Model Pattern by Martin Fowler, which seems just about the thing I was looking for. I have also found a - old-ish - tutorial on RCP UI testing (German only), which uses this pattern in an eclipse RCP context.

Now I'm wondering: is it generally possible to use PM in a GEF context, seeing that GEF explicitly uses MVC? Is MVVM an alternative?

Please note that I am prevented from using GMF for a number of reasons.

Many thanks!

Answer 1

Yes, it's definitely possible, and you have two choice.

First - is implement you own graphical notation model. I would suggest you using appreach like:

modelElement : ModelElement 1..1
x            : int          1..1
y            : int          1..1

Then load two models in EditingDomain (EMF will resolve cross-document references for you), create all missing Graphical Notation Elements e.t.c...

The other option is to use GMF or Graphiti. They have the model you're looking for out of the box, which will greatly simplify you life. At the cost of learning yet-another-monster-framework (in case of GMF). Graphiti, is easy (relative to GEF/GMF), but IMO is's less flexible. GMF, btw, will give you a 'free' TransactionalEditingDomain, which will handle all the commands, undos and redos for you. So, as in comments to you previous question, I would suggest you using GMF.

Oh, sorry, I didn't noticed what you wrote about GMF.

Then, the second option is to have Graphical Model inherit from Domain Model, and then code you GEF editor against this model.