211: Revise TypeHints and server side feedback for creation actions

- Add a new parameter to EdgeTypeHint, 'dynamic', indicating that new
edges need to check with the server before allowing creation
- Add a new Request/Response to implement this check

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/CheckEdgeTargetResultAction.java

@@ -0,0 +1,40 @@
+/********************************************************************************
+ * Copyright (c) 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.server.actions;
+
+/**
+ * {@link ResponseAction} for a {@link RequestCheckEdgeTargetAction}.
+ */
+public class CheckEdgeTargetResultAction extends ResponseAction {
+
+   public static final String KIND = "setTargetTypeHints";
+
+   private boolean isValid;
+
+   public CheckEdgeTargetResultAction() {
+      this(false);
+   }
+
+   public CheckEdgeTargetResultAction(final boolean isValid) {
+      super(KIND);
+      this.setValid(isValid);
+   }
+
+   public boolean isValid() { return isValid; }
+
+   public void setValid(final boolean isValid) { this.isValid = isValid; }
+
+}

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/RequestCheckEdgeTargetAction.java

@@ -0,0 +1,69 @@
+/********************************************************************************
+ * Copyright (c) 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.server.actions;
+
+import org.eclipse.glsp.server.types.EdgeTypeHint;
+
+/**
+ * A {@link RequestAction} used to check the validity of an edge being created. This is used
+ * to update creation feedback on the client side, for edges configured with a dynamic {@link EdgeTypeHint}.
+ *
+ * @see EdgeTypeHint#isDynamic()
+ * @see CheckEdgeTargetResultAction
+ */
+public class RequestCheckEdgeTargetAction extends RequestAction<CheckEdgeTargetResultAction> {
+
+   public static final String KIND = "requestCheckEdgeTarget";
+
+   private String edgeTypeId;
+
+   private String sourceElementId;
+
+   private String targetElementId;
+
+   public RequestCheckEdgeTargetAction() {
+      super(KIND);
+   }
+
+   /**
+    * The element type id of the Edge.
+    *
+    * @return
+    *         the element type id of the Edge.
+    */
+   public String getEdgeTypeId() { return edgeTypeId; }
+
+   public void setEdgeTypeId(final String edgeTypeId) { this.edgeTypeId = edgeTypeId; }
+
+   /**
+    * The ID of the source element of the edge being created.
+    *
+    * @return the ID of the source element of the edge being created.
+    */
+   public String getSourceElementId() { return sourceElementId; }
+
+   public void setSourceElementId(final String sourceElementId) { this.sourceElementId = sourceElementId; }
+
+   /**
+    * The ID of the target element of the edge being created.
+    *
+    * @return the ID of the target element of the edge being created.
+    */
+   public String getTargetElementId() { return targetElementId; }
+
+   public void setTargetElementId(final String targetElementId) { this.targetElementId = targetElementId; }
+
+}

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/di/DiagramModule.java

@@ -35,6 +35,7 @@
 import org.eclipse.glsp.server.actions.SetDirtyStateAction;
 import org.eclipse.glsp.server.actions.SetEditModeAction;
 import org.eclipse.glsp.server.actions.SetEditModeActionHandler;
+import org.eclipse.glsp.server.actions.CheckEdgeTargetResultAction;
 import org.eclipse.glsp.server.actions.SetViewportAction;
 import org.eclipse.glsp.server.actions.StartProgressAction;
 import org.eclipse.glsp.server.actions.TriggerEdgeCreationAction;
@@ -43,6 +44,7 @@
 import org.eclipse.glsp.server.di.scope.DiagramGlobalScope;
 import org.eclipse.glsp.server.di.scope.DiagramGlobalSingleton;
 import org.eclipse.glsp.server.diagram.DiagramConfiguration;
+import org.eclipse.glsp.server.diagram.DefaultRequestTargetTypeHintsActionHandler;
 import org.eclipse.glsp.server.diagram.RequestTypeHintsActionHandler;
 import org.eclipse.glsp.server.diagram.ServerConfigurationContribution;
 import org.eclipse.glsp.server.diagram.SetTypeHintsAction;
@@ -320,6 +322,7 @@ protected void configureClientActions(final MultiBinding<Action> binding) {
       binding.add(TriggerNodeCreationAction.class);
       binding.add(UpdateModelAction.class);
       binding.add(UpdateProgressAction.class);
+      binding.add(CheckEdgeTargetResultAction.class);
    }
 
    protected void configureActionHandlers(final MultiBinding<ActionHandler> binding) {
@@ -338,6 +341,7 @@ protected void configureActionHandlers(final MultiBinding<ActionHandler> binding
       binding.add(ComputedBoundsActionHandler.class);
       binding.add(SaveModelActionHandler.class);
       binding.add(UndoRedoActionHandler.class);
+      binding.add(DefaultRequestTargetTypeHintsActionHandler.class);
    }
 
    protected Class<? extends ActionHandlerRegistry> bindActionHandlerRegistry() {

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/diagram/DefaultRequestTargetTypeHintsActionHandler.java

@@ -0,0 +1,43 @@
+/********************************************************************************
+ * Copyright (c) 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.server.diagram;
+
+import java.util.List;
+
+import org.eclipse.glsp.server.actions.AbstractActionHandler;
+import org.eclipse.glsp.server.actions.Action;
+import org.eclipse.glsp.server.actions.CheckEdgeTargetResultAction;
+import org.eclipse.glsp.server.actions.RequestCheckEdgeTargetAction;
+
+import com.google.inject.Inject;
+
+/**
+ * Default handler implementation for {@link RequestCheckEdgeTargetAction}.
+ * This handler always rejects creation of dynamic Edges. Client applications
+ * should replace this default implementation with their own logic to
+ * conditionally accept creation of new edges configured with a Dynamic type.
+ */
+public class DefaultRequestTargetTypeHintsActionHandler extends AbstractActionHandler<RequestCheckEdgeTargetAction> {
+
+   @Inject
+   protected DiagramConfiguration diagramConfiguration;
+
+   @Override
+   protected List<Action> executeAction(final RequestCheckEdgeTargetAction actualAction) {
+      return List.of(new CheckEdgeTargetResultAction());
+   }
+
+}

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/diagram/DiagramConfiguration.java

@@ -71,7 +71,7 @@ public interface DiagramConfiguration {
    Optional<GraphExtension> getGraphExtension();
 
    default EdgeTypeHint createDefaultEdgeTypeHint(final String elementId) {
-      return new EdgeTypeHint(elementId, true, true, true, null, null);
+      return new EdgeTypeHint(elementId, true, true, true, false, null, null);
    }
 
    default ShapeTypeHint createDefaultShapeTypeHint(final String elementId) {

plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/types/EdgeTypeHint.java

@@ -17,6 +17,8 @@
 
 import java.util.List;
 
+import org.eclipse.glsp.server.actions.RequestCheckEdgeTargetAction;
+
 /**
  * {@link ElementTypeHint Element type hints} for edges.
  */
@@ -25,12 +27,19 @@ public class EdgeTypeHint extends ElementTypeHint {
    private boolean routable;
    private List<String> sourceElementTypeIds;
    private List<String> targetElementTypeIds;
+   private boolean dynamic = false;
 
    public EdgeTypeHint() {}
 
    public EdgeTypeHint(final String elementTypeId, final boolean repositionable, final boolean deletable,
       final boolean routable,
       final List<String> sourceElementTypeIds, final List<String> targetElementTypeIds) {
+      this(elementTypeId, repositionable, deletable, routable, false, sourceElementTypeIds, targetElementTypeIds);
+   }
+
+   public EdgeTypeHint(final String elementTypeId, final boolean repositionable, final boolean deletable,
+      final boolean routable, final boolean dynamic,
+      final List<String> sourceElementTypeIds, final List<String> targetElementTypeIds) {
       super(elementTypeId, repositionable, deletable);
       this.routable = routable;
       this.sourceElementTypeIds = sourceElementTypeIds;
@@ -53,4 +62,15 @@ public void setTargetElementTypeIds(final List<String> targetElementTypeIds) {
       this.targetElementTypeIds = targetElementTypeIds;
    }
 
+   /**
+    * Indicates whether this type hint is dynamic or not. Dynamic edge type hints
+    * require an additional runtime check before creating an edge, when checking
+    * source and target element types is not sufficient.
+    *
+    * @see RequestCheckEdgeTargetAction
+    */
+   public boolean isDynamic() { return dynamic; }
+
+   public void setDynamic(final boolean isDynamic) { this.dynamic = isDynamic; }
+
 }