Generating an EMF Model with Object Constraint Language

This tutorial is a step-by-step description of the process of creating an EMF model with additional constraints and generating a simple model editor for it. Following this tutorial will show how easy EMF makes it to go from a simple model definition to a fully functioning editor for that model.

The screenshots are based on version 2.1 of the Eclipse SDK and version 1.0 of EMF-OCL plugin

The model we will generate looks like this in UML :

context Book inv: pages>0 context Book inv: library.writers->includes(author)

We're going to show how an EMF-OCL model can be generated from an UML diagram (+ constraints)

Contents

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Step 0: Prerequisites

After installing the plugin package, verify that it is available in your Eclipse environment:

• Bring up the "Help/About Eclipse Platform" dialog.
  
   
• Click on "Plug-in Details".
  
   
• Check that the highlighted set of plugins are present.
  
   

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Step 1a: Make the Model

We're going to build the Ecore model using the eclipse interface. (library.ecore)

• Bring up the "File/New/Project..." dialog.
  
   
• Select "Eclipse Modeling Framework", choose "EMF Project" and click on "Next"
  
   
• Enter the Project name and click on "Next"
  
   
• Choose "Create empty project" and click on "Finish"
  
   

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Step 1b: Create an Ecore Model

Right-click on "Library/src" and Bring up the "New/Other..." dialog

 

Select "Example EMF Model Creation Wizards", choose "Ecore Model" and click on "Next"

 

Enter the File name and click on "Next"

 

Choose the Model Object "EPackage" and click on "Finish"

 

Give a name to your EPackage. Here it is "Library".

 

Add a class to your model. Here it is "Library".

 

Change the name of the class. (use the "help/Show View/Other/Basic/Properties" dialog if you don't have the window with properties)

 

Do the same for other classes.
You should have the following classes: (Library,Book and Writer)

 

Add an EEnum for the different types of books and give a name



 

Add an EEnum Literal by type of book, give a name and a value by EEnum Literal



 

Global view of Library.Ecore at this step:

 

Create the EData Type (Int, String for example) and put the correct OCLtype



 

Add EAttributes and change their properties (name, bounds, Etype, ...)



 

Add the different EReferences and change their properties:



 

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Step 1c: Add the OCL Constraints

• Add EConstraints :
  
  
  
• Add the different properties and clic on the expression button
  
  
  
• Enter the OCL expression and click on the validate button
  
  
  return on the Constraint tab and click on OK
  
  
• Do the same for the second constraint
  
   

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Step 2: Generate the EMF Model Code

Create the GenModel:

• In the Package Explorer view, right-click the "src" folder and select "New/Other..." from the pop-up menu.
  
   
• Select "Eclipse Modeling Framework" and "EMF Models". Click the "Next" button.
  
   
• Change the folder to "library/src/model", Change the file name to "library.genmodel" and click the "Next" button.
  
   
• Select "Load from EMF core model" and click the "Next" button.
  
   
• Click on "Browse File System", select your model (library.ecore), click the "Load" button and click on "Next".
  
   
• Select library package and click the "Finish" button.
  
   
• An Ecore model and a GenModel will be created. The GenModel, which controls code generation for the model, is opened in the main view.
  
   

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Step 3: Generate an Editor for the Model

A fully functional Eclipse editor can also be generated for any model. By default, it is split between two plugins: an "edit" plugin includes adapters that provide a structured view and perform command-based editing of the model objects; an "editor" plugin provides the UI for the editor and wizard.

• In the GenModel, right-click the "Library" model object and select "Generate Edit Code" from the pop-up menu.
  
   
• Right-click the model object and select "Generate Editor Code" from the pop-up menu.
  
   
• Observe the generated projects, with "edit" and "editor" suffixes.
  
   

In general, if you wish to generate the model, edit, and editor plugins in a single step, you can do so by selecting "Generate All" from the pop-up menu.

The code should be compiled automatically as it is generated, and should recompile whenever it is changed. If you have disabled automatic building in the workbench preferences, you can initiate compilation manually:

• Select "Rebuild All" from the "Project" menu.
  
   
• There should no errors in the "library", "library.edit", and "library.editor" projects if you import a correct core model.
  
   

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Step 4: Run the Generated Editor

In order to run plugins in a runtime workbench, a lunch configuration must first be set up:

• Select "Run..." from the "Run" menu.
  
   
• Select "Run-time Workbench" and click the "New" button.
  
   
• You may want to change the configuration's name to something more recognizable. Then, switch to the "Plug-ins and Fragments" tab.
  
   
• Pick "Choose plugin-ins and fragments to launch from the list", and then select the top-level "External Plug-ins".
  
   
• Switch to the "Common" tab, select "Display in favorites menu: Run", and click the "Apply" button.
  
   

A runtime workbench can be launched from the "Launch Configurations" dialog by clicking on the "Run" button. Once the launch configuration has been set up, it can also be launched from the "Run" button on the toolbar.

• Select the new launch configuration from the "Run" button drop-down.
  
   
• Wait for a second instance of the Eclipse platform to come up. Bring up the "Help/About Eclipse Platform" dialog, click on the "Plug-in Details" button, and verify that the generated plugins are there.
  
   

The library model wizard can now be used to create a new instance of the model.

• Bring up the "File/New/Project..." dialog.
  
   
• Select "Simple" and "Project". Click the "Next" button.
  
   
• Give the project a name and click the "Finish" button.
  
   
• Right-click the project and select "New/Other..." from the pop-up menu.
  
   
• Select "Example EMF Model Creation Wizards" and "Library Model". Click the "Next" button.
  
   
• Enter a file name for the library model. Make sure it ends with a ".library" extension. Then click the "Next" button.
  
   
• Select "Library" as the model object, and click the "Finish" button.
  
   

The root object in this editor corresponds to the "My.library" resource. Under it lies a single library, the object which was selected as the model object in the wizard.

• The newly created library model is opened in the main view.
  Expand the "platform:/resource/librarytest/My.library" resource to see the library object. Select it.
  
   
• Right-click on the library and select "New Child/Book" from the pop-up menu to add a new book to the library.
  Enter the title of the book in the Properties view.
  
   
• Similarly, a bwriter can be added to the library.
  
   
• All the book's attributes and references can edited in the Properties view.
  
   
• You can save, close, and then re-open the model using the text editor if you wish to see the saved model in XMI format.
  

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