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EMF allows to store the model content via the EMF persistence framework. By default EMF uses XMI (XML Metadata Interchange). XMI is an standard for exchanging metadata information via Extensible Markup Language (XML).

The generated model code looks like normal Java code and can be used like normal Java code. The *PackageImpl.java.init() method needs to be called before doing anything else as this method initializes the model and the listeners.

The following demonstrates how you create a model instance via Java code, save it and load it again.

Create a new plugin project "de.vogella.emf.webpage.instance". Add the following dependency to your "plugin.xml".

				
package writeWebpage;

import java.io.IOException;
import java.util.Collections;
import java.util.Map;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.eclipse.emf.ecore.xmi.impl.XMIResourceFactoryImpl;

import datamodel.website.MyWeb;
import datamodel.website.Webpage;
import datamodel.website.WebsiteFactory;
import datamodel.website.WebsitePackage;
import datamodel.website.impl.WebsitePackageImpl;

public class CreateSaveTester {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// Initialize the model
		WebsitePackage.eINSTANCE.eClass();
		// Retrieve the default factory singleton
		WebsiteFactory factory = WebsiteFactory.eINSTANCE;

		// Create the content of the model via this program
		MyWeb myWeb = factory.createMyWeb();
		Webpage page = factory.createWebpage();
		page.setName("index");
		page.setDescription("Main webpage");
		page.setKeywords("Eclipse, EMF");
		page.setTitle("Eclipse EMF");
		myWeb.getPages().add(page);

		// As of here we preparing to save the model content

		// Register the XMI resource factory for the .website extension

		Resource.Factory.Registry reg = Resource.Factory.Registry.INSTANCE;
		Map<String, Object> m = reg.getExtensionToFactoryMap();
		m.put("website", new XMIResourceFactoryImpl());

		// Obtain a new resource set
		ResourceSet resSet = new ResourceSetImpl();

		// Create a resource
		Resource resource = resSet.createResource(URI
				.createURI("website/My2.website"));
		// Get the first model element and cast it to the right type, in my
		// example everything is hierarchical included in this first node
		resource.getContents().add(myWeb);

		// Now save the content.
		try {
			resource.save(Collections.EMPTY_MAP);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

			

The following coding can be used to load an existing model.

				

package writeWebpage;

import java.util.Map;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.eclipse.emf.ecore.xmi.impl.XMIResourceFactoryImpl;

import datamodel.website.MyWeb;
import datamodel.website.WebsitePackage;
import datamodel.website.impl.WebsitePackageImpl;

public class EMFModelLoad {
	public MyWeb load() {
		// Initialize the model
		WebsitePackage.eINSTANCE.eClass();
		
		// Register the XMI resource factory for the .website extension

		Resource.Factory.Registry reg = Resource.Factory.Registry.INSTANCE;
		Map<String, Object> m = reg.getExtensionToFactoryMap();
		m.put("website", new XMIResourceFactoryImpl());

		// Obtain a new resource set
		ResourceSet resSet = new ResourceSetImpl();

		// Get the resource
		Resource resource = resSet.getResource(URI
				.createURI("website/My.website"), true);
		// Get the first model element and cast it to the right type, in my
		// example everything is hierarchical included in this first node
		MyWeb myWeb = (MyWeb) resource.getContents().get(0);
		return myWeb;
	}

}

			

You can then access the model content via standard Java coding.

				
package writeWebpage;

import java.util.Iterator;

import datamodel.website.MyWeb;
import datamodel.website.Webpage;

public class LoadTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// Loading the existing model
		EMFModelLoad loader = new EMFModelLoad();
		MyWeb myWeb = loader.load();
		// Accessing the model information
		System.out.println(myWeb.getDescription());
		System.out.println(myWeb.getTitle());
		// Lets see what info the webpage has
		for (Iterator<Webpage> iterator = myWeb.getPages().iterator(); iterator
				.hasNext();) {
			Webpage page = iterator.next();
			System.out.println("Name : " + page.getName());
			// We could also iterate over the Articles...
		}
	}
}

			

http://www.vogella.de/code/codeeclipse.html Source Code of Examples

http://www.eclipse.org/modeling/emf Eclipse EMF Homepage

http://www.eclipse.org/modeling/emf/docs/ EMF Documentation

http://www.ibm.com/developerworks/opensource/library/os-ecemf1 Model with the Eclipse Modeling Framework, Part 1: Create UML models and generate code

http://www.ibm.com/developerworks/opensource/library/os-ecemf2 Model with the Eclipse Modeling Framework, Part 2: Generate code with Eclipse's Java Emitter Templates

http://www.eclipse.org/m2m/atl/ ATL allows model to model transformation for EMF

Eclipse.org Homepage

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