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EMF Integration

The lionweb-java-emf module provides bidirectional conversion between LionWeb and the Eclipse Modeling Framework (EMF/Ecore). This lets you:

  • Export a LionWeb language (metamodel) to an Ecore EPackage for use in Eclipse tools.
  • Import an existing Ecore EPackage as a LionWeb Language.
  • Export LionWeb nodes to EMF EObject instances.
  • Import EMF EObject instances as LionWeb nodes.

Dependencies​

dependencies {
    implementation("io.lionweb:lionweb-2024.1-core:$lionwebVersion")
    implementation("io.lionweb:lionweb-2024.1-emf:$lionwebVersion")
    // Required for LionCore built-in elements that have no Ecore equivalent
    implementation("io.lionweb:lionweb-2024.1-emf-builtins:$lionwebVersion")
}

Exporting a Language to Ecore​

Use EMFMetamodelExporter to convert a LionWeb Language into an Ecore EPackage:

import io.lionweb.emf.EMFMetamodelExporter;
import io.lionweb.language.Language;
import org.eclipse.emf.ecore.EPackage;

Language myLanguage = ...; // your LionWeb language

EMFMetamodelExporter exporter = new EMFMetamodelExporter();
EPackage ePackage = exporter.exportLanguage(myLanguage);

To export multiple languages into a single EMF Resource:

import org.eclipse.emf.ecore.resource.Resource;
import java.util.List;

Resource resource = exporter.exportResource(List.of(myLanguage, anotherLanguage));

Importing a Language from Ecore​

Use EMFMetamodelImporter to convert an Ecore EPackage into a LionWeb Language:

import io.lionweb.emf.EMFMetamodelImporter;
import io.lionweb.language.Language;
import org.eclipse.emf.ecore.EPackage;

EPackage ePackage = ...; // your Ecore package

EMFMetamodelImporter importer = new EMFMetamodelImporter();
Language language = importer.importEPackage(ePackage);

To import all languages from a Resource:

List<Language> languages = importer.importResource(resource);

Exporting Nodes to EMF Objects​

Use EMFModelExporter to convert LionWeb nodes into EMF EObject instances. You must first set up the exporter with the language mapping (so it knows which EClass to use for each Concept).

import io.lionweb.emf.EMFModelExporter;
import io.lionweb.model.Node;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import java.util.List;

EMFModelExporter modelExporter = new EMFModelExporter();
Resource resource = modelExporter.exportResource(List.of(rootNode));

Importing EMF Objects as Nodes​

Use EMFModelImporter to convert EMF EObject instances back into LionWeb nodes:

import io.lionweb.emf.EMFModelImporter;
import io.lionweb.model.Node;
import org.eclipse.emf.ecore.resource.Resource;
import java.util.List;

EMFModelImporter modelImporter = new EMFModelImporter();
List<Node> nodes = modelImporter.importResource(resource);

About emf-builtins​

Some LionCore built-in elements (such as INamed, IKeyed, and primitive types) have no direct Ecore equivalent. The emf-builtins module provides a companion EPackage that fills this gap:

  • nsURI: http://lionweb.io/lionweb-java/emf/core/builtins/2023.1
  • Bundle-SymbolicName: io.lionweb.emf.builtins

This package is automatically used by EMFMetamodelExporter and EMFMetamodelImporter when they encounter LionCore built-in types, so you only need to add it as a dependency — no further configuration is required.