Extended workflow example by injecting non-default state

examples/org.eclipse.glsp.example.workflow/META-INF/MANIFEST.MF

@@ -27,5 +27,6 @@ Require-Bundle: org.eclipse.glsp.layout;bundle-version="[2.0.0,3.0.0)",
  org.eclipse.glsp.server.websocket;bundle-version="[2.0.0,3.0.0)",
  org.eclipse.elk.core;bundle-version="0.8.1",
  org.eclipse.elk.alg.layered;bundle-version="0.8.1",
- org.eclipse.elk.graph;bundle-version="0.8.1"
+ org.eclipse.elk.graph;bundle-version="0.8.1",
+ com.google.gson;bundle-version="2.8.7"
 Import-Package: org.apache.logging.log4j;version="2.17.1"

examples/org.eclipse.glsp.example.workflow/src/org/eclipse/glsp/example/workflow/WorkflowDiagramModule.java

@@ -47,6 +47,7 @@
 import org.eclipse.glsp.server.features.contextactions.ContextActionsProvider;
 import org.eclipse.glsp.server.features.contextactions.RequestContextActionsHandler;
 import org.eclipse.glsp.server.features.contextmenu.ContextMenuItemProvider;
+import org.eclipse.glsp.server.features.core.model.GModelFactory;
 import org.eclipse.glsp.server.features.core.model.SourceModelStorage;
 import org.eclipse.glsp.server.features.directediting.ContextEditValidator;
 import org.eclipse.glsp.server.features.directediting.LabelEditValidator;
@@ -58,8 +59,8 @@
 import org.eclipse.glsp.server.features.typehints.EdgeCreationChecker;
 import org.eclipse.glsp.server.features.validation.ModelValidator;
 import org.eclipse.glsp.server.gmodel.GModelDiagramModule;
-import org.eclipse.glsp.server.gmodel.GModelStorage;
 import org.eclipse.glsp.server.layout.LayoutEngine;
+import org.eclipse.glsp.server.model.GModelState;
 import org.eclipse.glsp.server.operations.OperationHandler;
 
 public class WorkflowDiagramModule extends GModelDiagramModule {
@@ -71,7 +72,17 @@ protected Class<? extends DiagramConfiguration> bindDiagramConfiguration() {
 
    @Override
    protected Class<? extends SourceModelStorage> bindSourceModelStorage() {
-      return GModelStorage.class;
+      return WorkflowModelStorage.class;
+   }
+
+   @Override
+   protected Class<? extends GModelState> bindGModelState() {
+      return WorkflowModelState.class;
+   }
+
+   @Override
+   protected Class<? extends GModelFactory> bindGModelFactory() {
+      return WorkflowModelFactory.class;
    }
 
    @Override

examples/org.eclipse.glsp.example.workflow/src/org/eclipse/glsp/example/workflow/WorkflowModelFactory.java

@@ -0,0 +1,51 @@
+/********************************************************************************
+ * Copyright (c) 2019-2023 EclipseSource and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+package org.eclipse.glsp.example.workflow;
+
+import com.google.inject.Inject;
+import org.eclipse.glsp.graph.GModelRoot;
+import org.eclipse.glsp.server.features.core.model.GModelFactory;
+
+/**
+ * This class provides the method to transform a source model into a GModel, updating the {@link GModelRoot}.
+ *
+ * This is, however, only relevant in cases where the source model is not already a valid GModel.
+ *
+ * Here, this custom implementation only serves to provide an entrypoint, but for a more extensive example
+ * look to <a href="https://eclipse.dev/glsp/documentation/gmodel/#graphical-model-factory">
+ *     https://eclipse.dev/glsp/documentation/gmodel/#graphical-model-factory</a>.
+ */
+public class WorkflowModelFactory implements GModelFactory {
+
+    @Inject
+    protected WorkflowModelState modelState;
+
+    /**
+     * Since this is an example using Workflow, which inherently already uses a GModel format, no difference
+     * exists between the underlying source model and `root`. Therefore all handlers directly update the
+     * root, making this method detrimental after first model creation.
+     *
+     * If other handlers are instead written to update `modelState.model`, then the root has to be updated
+     * after every change.
+     */
+    @Override
+    public void createGModel() {
+        if (modelState.getRoot() == null) {
+            modelState.updateRoot(modelState.getModel());
+            modelState.getRoot().setRevision(-1);
+        }
+    }
+}

examples/org.eclipse.glsp.example.workflow/src/org/eclipse/glsp/example/workflow/WorkflowModelState.java

@@ -0,0 +1,49 @@
+/********************************************************************************
+ * Copyright (c) 2019-2023 EclipseSource and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+package org.eclipse.glsp.example.workflow;
+
+import org.eclipse.glsp.graph.GGraph;
+import org.eclipse.glsp.graph.GModelRoot;
+import org.eclipse.glsp.server.model.DefaultGModelState;
+import org.eclipse.glsp.server.model.GModelState;
+import org.eclipse.glsp.server.features.core.model.GModelFactory;
+
+/**
+ * This model state serves to demonstrate how to extend or create a custom model state.
+ *
+ * While this may not be necessary when handling JSON formatted graphs that already
+ * correspond to a GModel (as the Workflow example does), since {@link DefaultGModelState}
+ * is sufficient, it nonetheless provides an adequte example for custom formats.
+ */
+public class WorkflowModelState extends DefaultGModelState {
+
+    /**
+     * The source model that needs to be transformed into a GModel and its {@link GModelRoot}.
+     * It is saved in the {@link GModelState} in order to later be available in the
+     * corresponding {@link GModelFactory}.
+     *
+     * Its type solely depends on the used source model.
+     */
+    private GGraph model;
+
+    public GGraph getModel() {
+        return model;
+    }
+
+    public void setModel(GGraph model) {
+        this.model = model;
+    }
+}

examples/org.eclipse.glsp.example.workflow/src/org/eclipse/glsp/example/workflow/WorkflowModelStorage.java

@@ -0,0 +1,81 @@
+/********************************************************************************
+ * Copyright (c) 2019-2023 EclipseSource and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+package org.eclipse.glsp.example.workflow;
+
+import com.google.gson.Gson;
+import com.google.inject.Inject;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Reader;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import org.eclipse.glsp.graph.GGraph;
+import org.eclipse.glsp.server.actions.SaveModelAction;
+import org.eclipse.glsp.server.features.core.model.RequestModelAction;
+import org.eclipse.glsp.server.features.core.model.SourceModelStorage;
+import org.eclipse.glsp.server.gson.GraphGsonConfigurationFactory;
+import org.eclipse.glsp.server.types.GLSPServerException;
+import org.eclipse.glsp.server.utils.ClientOptionsUtil;
+import org.eclipse.glsp.server.gmodel.GModelStorage;
+
+/**
+ * This {@link SourceModelStorage} serves as a naive implementation similar to the default {@link GModelStorage}.
+ * The main difference being that the source model is not directly instantiated as GModel, which works
+ * in the Workflow example (since its data format is already a valid GModel), but not generally. Therefore,
+ * this example is more easily applicable to custom model formats.
+ *
+ * The model saved here is later on transformed in {@link WorkflowModelFactory} and has to be updated in the handlers,
+ *  if source model and GModel are different.
+ */
+public class WorkflowModelStorage implements SourceModelStorage {
+
+    @Inject
+    protected WorkflowModelState modelState;
+
+    protected Gson gson;
+
+    @Inject
+    public void configureGson(final GraphGsonConfigurationFactory gsonConfigurator) {
+        gson = gsonConfigurator.configureGson().setPrettyPrinting().create();
+    }
+
+    @Override
+    public void loadSourceModel(final RequestModelAction action) {
+        final File file = ClientOptionsUtil.getSourceUriAsFile(action.getOptions()).orElseThrow();
+        try (Reader reader = new InputStreamReader(new FileInputStream(file), StandardCharsets.UTF_8)) {
+            var model = gson.fromJson(reader, GGraph.class);
+            modelState.setModel(model);
+            modelState.setProperty(ClientOptionsUtil.SOURCE_URI, action.getOptions().get(ClientOptionsUtil.SOURCE_URI));
+        } catch (IOException e) {
+            throw new GLSPServerException("Could not load model from file: " + file.toURI().toString(), e);
+        }
+    }
+
+    @Override
+    public void saveSourceModel(final SaveModelAction action) {
+        File file = ClientOptionsUtil.getAsFile(modelState.getProperty(ClientOptionsUtil.SOURCE_URI, String.class).orElseThrow());
+        try (Writer writer = new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8)) {
+            gson.toJson(modelState.getRoot(), GGraph.class, writer);
+        } catch (IOException e) {
+            throw new GLSPServerException("An error occured during save process.", e);
+        }
+    }
+
+}