Add change container handler

examples/workflow-server/src/common/handler/change-container-workflow-handler.ts

@@ -0,0 +1,45 @@
+/********************************************************************************
+ * Copyright (c) 2026 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
+ * http://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
+ ********************************************************************************/
+import { ChangeContainerOperation, GCompartment, GModelChangeContainerOperationHandler, GModelElement } from '@eclipse-glsp/server';
+import { injectable } from 'inversify';
+import { Category } from '../graph-extension';
+import { ModelTypes } from '../util/model-types';
+
+/**
+ * Workflow-specific {@link GModelChangeContainerOperationHandler} that redirects reparenting into a
+ * {@link Category}'s structure compartment. The client references the outer {@link Category} node as
+ * container, so the actual child container (the `struct` compartment) has to be resolved on the server side.
+ */
+@injectable()
+export class ChangeContainerWorkflowHandler extends GModelChangeContainerOperationHandler {
+    override getContainer(operation: ChangeContainerOperation): GModelElement | undefined {
+        const container = super.getContainer(operation);
+        if (container instanceof Category) {
+            const structComp = this.getCategoryCompartment(container);
+            if (structComp) {
+                return structComp;
+            }
+        }
+        return container;
+    }
+
+    getCategoryCompartment(category: Category): GCompartment | undefined {
+        return category.children
+            .filter(child => child instanceof GCompartment)
+            .map(child => child as GCompartment)
+            .find(comp => ModelTypes.STRUCTURE === comp.type);
+    }
+}

examples/workflow-server/src/common/workflow-diagram-module.ts

@@ -22,6 +22,7 @@ import {
     DiagramConfiguration,
     EdgeCreationChecker,
     GLSPServerInitializer,
+    GModelChangeContainerOperationHandler,
     GModelDiagramModule,
     InstanceMultiBinding,
     LabelEditValidator,
@@ -35,6 +36,7 @@ import {
     SourceModelStorage
 } from '@eclipse-glsp/server';
 import { injectable } from 'inversify';
+import { ChangeContainerWorkflowHandler } from './handler/change-container-workflow-handler';
 import { CreateAutomatedTaskHandler } from './handler/create-automated-task-handler';
 import { CreateCategoryHandler } from './handler/create-category-handler';
 import { CreateDecisionNodeHandler } from './handler/create-decision-node-handler';
@@ -89,6 +91,7 @@ export class WorkflowDiagramModule extends GModelDiagramModule {
         binding.add(CreateDecisionNodeHandler);
         binding.add(CreateCategoryHandler);
         binding.add(EditTaskOperationHandler);
+        binding.rebind(GModelChangeContainerOperationHandler, ChangeContainerWorkflowHandler);
     }
 
     protected bindDiagramConfiguration(): BindingTarget<DiagramConfiguration> {

packages/server/src/common/gmodel/change-container-operation-handler.ts

@@ -0,0 +1,81 @@
+/********************************************************************************
+ * Copyright (c) 2025-2026 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
+ * http://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
+ ********************************************************************************/
+import { GModelElement, isGBoundsAware } from '@eclipse-glsp/graph';
+import { ChangeContainerOperation, MaybePromise, Point } from '@eclipse-glsp/protocol';
+import { injectable } from 'inversify';
+import { Command } from '../command/command';
+import { getRelativeLocation } from '../utils/layout-util';
+import { GModelOperationHandler } from './gmodel-operation-handler';
+
+/**
+ * Applies {@link ChangeContainerOperation} directly to the GModel by re-parenting the element
+ * from its current container to the target container.
+ */
+@injectable()
+export class GModelChangeContainerOperationHandler extends GModelOperationHandler {
+    operationType = ChangeContainerOperation.KIND;
+
+    createCommand(operation: ChangeContainerOperation): MaybePromise<Command | undefined> {
+        const element = this.modelState.index.find(operation.elementId);
+        const targetContainer = this.getContainer(operation);
+        if (!element || !targetContainer) {
+            return undefined;
+        }
+        // resolve elements lazily inside the closure so that references remain valid
+        // even when preceding commands in a CompoundCommand rebuild the model tree
+        return this.commandOf(() => {
+            const currentElement = this.modelState.index.find(operation.elementId);
+            const currentContainer = this.getContainer(operation);
+            if (currentElement && currentContainer) {
+                this.executeChangeContainer(currentElement, currentContainer, operation.location);
+            }
+        });
+    }
+
+    /**
+     * Returns the {@link GModelElement} that will receive the reparented element. By default this is the
+     * target element referenced by {@link ChangeContainerOperation.targetContainerId}, but it could also
+     * be e.g. an intermediate compartment or a different node. Subclasses can override this to redirect the
+     * reparented element into another container.
+     *
+     * @param operation the operation to resolve the container for.
+     * @returns the {@link GModelElement} that will contain the reparented element, or `undefined` if it cannot be resolved.
+     */
+    getContainer(operation: ChangeContainerOperation): GModelElement | undefined {
+        return this.modelState.index.find(operation.targetContainerId);
+    }
+
+    protected executeChangeContainer(element: GModelElement, targetContainer: GModelElement, location?: Point): void {
+        // remove from current parent
+        const currentParent = element.parent;
+        if (currentParent) {
+            const index = currentParent.children.indexOf(element);
+            if (index >= 0) {
+                currentParent.children.splice(index, 1);
+            }
+        }
+        // add to new parent
+        targetContainer.children.push(element);
+        element.parent = targetContainer;
+        // update position relative to the new container
+        if (location && isGBoundsAware(element)) {
+            const relativeLocation = getRelativeLocation(location, targetContainer);
+            if (relativeLocation) {
+                element.position = relativeLocation;
+            }
+        }
+    }
+}

packages/server/src/common/gmodel/gmodel-diagram-module.ts

@@ -1,5 +1,5 @@
 /********************************************************************************
- * Copyright (c) 2022-2023 STMicroelectronics and others.
+ * Copyright (c) 2022-2026 STMicroelectronics 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
@@ -25,6 +25,7 @@ import { DefaultModelState, ModelState } from '../features/model/model-state';
 import { OperationHandler, OperationHandlerConstructor } from '../operations/operation-handler';
 import { GModelApplyLabelEditOperationHandler } from './apply-label-edit-operation-handler';
 import { GModelChangeBoundsOperationHandler } from './change-bounds-operation-handler';
+import { GModelChangeContainerOperationHandler } from './change-container-operation-handler';
 import { GModelChangeRoutingPointsOperationHandler } from './change-routing-points-operation-handler';
 import { GModelCutOperationHandler } from './cut-operation-handler';
 import { GModelDeleteOperationHandler } from './delete-operation-handler';
@@ -41,6 +42,7 @@ import { GModelReconnectEdgeOperationHandler } from './reconnect-edge-operation-
  * - {@link RequestClipboardDataActionHandler} to {@link ActionHandler}
  * - {@link GModelApplyLabelEditOperationHandler} to {@link OperationHandler}
  * - {@link GModelChangeBoundsOperationHandler} to {@link OperationHandler}
+ * - {@link GModelChangeContainerOperationHandler} to {@link OperationHandler}
  * - {@link GModelCutOperationHandler} to {@link OperationHandler}
  * - {@link GModelDeleteOperationHandler} to {@link OperationHandler}
  * - {@link GModelPasteOperationHandler} to {@link OperationHandler}
@@ -67,6 +69,7 @@ export abstract class GModelDiagramModule extends DiagramModule {
         super.configureOperationHandlers(binding);
         binding.add(GModelApplyLabelEditOperationHandler);
         binding.add(GModelChangeBoundsOperationHandler);
+        binding.add(GModelChangeContainerOperationHandler);
         binding.add(GModelCutOperationHandler);
         binding.add(GModelDeleteOperationHandler);
         binding.add(GModelPasteOperationHandler);

packages/server/src/common/index.ts

@@ -71,6 +71,7 @@ export * from './features/validation/model-validator';
 export * from './features/validation/request-markers-handler';
 export * from './gmodel/apply-label-edit-operation-handler';
 export * from './gmodel/change-bounds-operation-handler';
+export * from './gmodel/change-container-operation-handler';
 export * from './gmodel/change-routing-points-operation-handler';
 export * from './gmodel/cut-operation-handler';
 export * from './gmodel/delete-operation-handler';

packages/server/src/common/protocol/glsp-server.ts

@@ -14,8 +14,10 @@
  * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
  ********************************************************************************/
 import {
+    Action,
     ActionMessage,
     Args,
+    CompoundOperation,
     DisposeClientSessionParameters,
     GLSPClientProxy,
     GLSPServer,
@@ -167,7 +169,7 @@ export class DefaultGLSPServer implements GLSPServer {
 
     process(message: ActionMessage): void {
         this.validateServerInitialized();
-        this.logger.info(`process [action=${message.action.kind}, clientId=${message.clientId}]`);
+        this.logger.info(`process [action=${this.formatAction(message.action)}, clientId=${message.clientId}]`);
         const clientSessionId = message.clientId;
         const clientSession = this.clientSessions.get(clientSessionId);
         if (!clientSession) {
@@ -228,6 +230,14 @@ export class DefaultGLSPServer implements GLSPServer {
         this.sendToClient({ clientId: message.clientId, action: errorAction });
     }
 
+    protected formatAction(action: Action): string {
+        if (CompoundOperation.is(action)) {
+            const children = action.operationList.map(op => op.kind).join(', ');
+            return `${action.kind}(${children})`;
+        }
+        return action.kind;
+    }
+
     protected sendToClient(message: ActionMessage): void {
         this.glspClientProxy.process(message);
     }