This tutorial will be all about the Eclipse Modeling Framework, one of the core technologies in the Eclipse universe. You will learn what metamodels are and how to create them, how to generate an editor for instances of your metamodels, and how to load and save such instances. All of this just goes to teach you all you need to know for the final step: designing and implementing a metamodel for Turing Machines as well as a head controller that can execute Turing Machines specified in terms of that metamodel. Once you're done with this tutorial, you will have an application that looks something like this:

Preliminaries

The Eclipse Modeling Framework (EMF) belongs to the most important technologies in the Eclipse world. One of the more recent indicators of this is its being used to describe the very foundation of Eclipse 4 (or e4, which of course sounds way cooler) applications: the application model. We might come back to the application model in the project phase of our practical. Another indication is that EMF has come to be the foundation of most other modeling-related Eclipse projects. Thus, there is important stuff to be learned in this tutorial!

Let's try to get a first idea of what EMF does. Essentially, EMF helps you to write the code necessary to represent models (or domain models, as they are also called). So, what are models? An example of a model that you have all encountered before is a UML class diagram. In such a model, classes are related to one another using different types of relations: inheritance relations, associations, aggregations, compositions,... Working on such a model requires code that represents the model and that allows you to change its structure. EMF can help you write that code.

However, EMF can do that for all kinds of models. To generate the code for a specific kind of models, EMF needs to know what kinds of entities and relationships between the entities there are in those models. This is where a metamodel comes into play: metamodels describe the structure of your models. They are to your models what grammar is to your programming languages. When working with EMF, you usually start by defining the metamodel (syntax of your models), and then proceed to let EMF generate the code required to represent such models.

You can also have EMF generate simple editors to load, edit, and save models corresponding to your metamodel.

EMF also contains a bunch of tools that can help you with everything surrounding modeling, such as loading and saving models. EMF usually serializes models using the XMI (XML Metadata Interchange) format, which is an XML file geared towards the representation of models. The classes generated by EMF also have built-in facilities to, for instance, help you observe changes in the model instances.

Required Software

Your Eclipse installation already has everything we need for this tutorial. In fact, that's one reason why we suggested you install the Eclipse Modeling Tools. You will again be working on your branch of our tutorials Git repository.

Finding Documentation

For an introduction to EMF, here's a few suggestions to get you started:

• The Wikipedia article on metamodeling may be i
• The Eclipse online help system contains a section on EMF, complete with an introduction and tutorials.
• There is a book on EMF, which is a great resource. The library may have copies available. We also have at least one copy at our office, so feel free to drop in and read it. (We also have tea and a sofa, so there's no lack of proper reading atmosphere... )
• Among many other helpful tutorials, Lars Vogel, an active Eclipse developer, has also written a tutorial on EMF.