Server side implementation of ACTVT 93: The Share client exposes the diagram associated with a workflow (ALF-8634).

WorkflowService Java API now has a hasWorkflowImage() method which is used in the existing workflow instance REST API to determine whether to return a URL to the diagram ("diagramUrl" property) in the response. A new REST API has also been added (/api/workflow-instances/<id>/diagram) to allow retrieval of the PNG image data.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@28485 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

config/alfresco/templates/webscripts/org/alfresco/repository/workflow/workflow-instance-diagram.get.desc.xml

@@ -0,0 +1,15 @@
+<webscript>
+   <shortname>Get Workflow Instance Diagram</shortname>
+   <description>Streams an image representing the current state of a workflow instance, if one is present</description>
+   <url>/api/workflow-instances/{workflow_instance_id}/diagram</url>
+   <format default="">argument</format>
+   <authentication>user</authentication>
+   <transaction allow="readonly">required</transaction>
+   <lifecycle>public_api</lifecycle>
+   <args>
+      <arg>
+         <shortname>workflow_instance_id</shortname>
+         <description>The id of workflow process instance to retrieve a diagram for.</description>
+      </arg>
+   </args>
+</webscript>

config/alfresco/templates/webscripts/org/alfresco/repository/workflow/workflow-instance.get.desc.xml

@@ -44,6 +44,7 @@
                      "lastName": string
                   },
                   "definitionUrl": string,
+                  "diagramUrl": string,
                   "startTaskInstanceId": string,
                   "definition":
                   {

config/alfresco/templates/webscripts/org/alfresco/repository/workflow/workflow.lib.ftl

@@ -125,6 +125,7 @@
    null,
    </#if>
    "definitionUrl": "${workflowInstance.definitionUrl}"<#if detailed>,
+   "diagramUrl": <#if workflowInstance.diagramUrl??>"${workflowInstance.diagramUrl}"<#else>null</#if>,
    "startTaskInstanceId": "${workflowInstance.startTaskInstanceId}",
    "definition": 
    <@workflowDefinitionJSON workflowDefinition=workflowInstance.definition detailed=true/>

config/alfresco/web-scripts-application-context.xml

@@ -1047,6 +1047,13 @@
           class="org.alfresco.repo.web.scripts.workflow.WorkflowInstanceGet"
           parent="abstractWorkflowWebScript"></bean>
           
+    <!-- Retrieves the diagram for a specific workflow instance -->
+    <bean id="webscript.org.alfresco.repository.workflow.workflow-instance-diagram.get"
+          class="org.alfresco.repo.web.scripts.workflow.WorkflowInstanceDiagramGet"
+          parent="webscript">
+       <property name="workflowService" ref="WorkflowService" />
+    </bean>
+
     <!-- Retrieves all workflow instances. -->
     <bean id="webscript.org.alfresco.repository.workflow.workflow-instances.get"
           class="org.alfresco.repo.web.scripts.workflow.WorkflowInstancesGet"

source/java/org/alfresco/repo/web/scripts/workflow/WorkflowInstanceDiagramGet.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2005-2010 Alfresco Software Limited.
+ *
+ * This file is part of Alfresco
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.alfresco.repo.web.scripts.workflow;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Map;
+
+import javax.servlet.http.HttpServletResponse;
+
+import org.alfresco.repo.content.MimetypeMap;
+import org.alfresco.service.cmr.workflow.WorkflowInstance;
+import org.alfresco.service.cmr.workflow.WorkflowService;
+import org.springframework.extensions.webscripts.AbstractWebScript;
+import org.springframework.extensions.webscripts.Cache;
+import org.springframework.extensions.webscripts.WebScriptException;
+import org.springframework.extensions.webscripts.WebScriptRequest;
+import org.springframework.extensions.webscripts.WebScriptResponse;
+import org.springframework.util.FileCopyUtils;
+
+/**
+ * Java backed implementation for REST API to retrieve a diagram of a workflow instance.
+ * 
+ * @author Gavin Cornwell
+ * @since 4.0
+ */
+public class WorkflowInstanceDiagramGet extends AbstractWebScript
+{
+    protected WorkflowService workflowService;
+    
+    public void setWorkflowService(WorkflowService workflowService)
+    {
+        this.workflowService = workflowService;
+    }
+    
+    @Override
+    public void execute(WebScriptRequest req, WebScriptResponse res) throws IOException
+    {
+        Map<String, String> params = req.getServiceMatch().getTemplateVars();
+
+        // getting workflow instance id from request parameters
+        String workflowInstanceId = params.get("workflow_instance_id");
+        
+        WorkflowInstance workflowInstance = workflowService.getWorkflowById(workflowInstanceId);
+
+        // workflow instance was not found -> return 404
+        if (workflowInstance == null)
+        {
+            throw new WebScriptException(HttpServletResponse.SC_NOT_FOUND, "Unable to find workflow instance with id: " + workflowInstanceId);
+        }
+        
+        // check whether there is a diagram available
+        if (!workflowService.hasWorkflowImage(workflowInstanceId))
+        {
+            throw new WebScriptException(HttpServletResponse.SC_NOT_FOUND, "Unable to find diagram for workflow instance with id: " + workflowInstanceId);
+        }
+        
+        // set mimetype for the content and the character encoding + length for the stream
+        res.setContentType(MimetypeMap.MIMETYPE_IMAGE_PNG);
+        
+        // set caching (never cache)
+        Cache cache = new Cache();
+        cache.setNeverCache(true);
+        cache.setMustRevalidate(true);
+        cache.setMaxAge(0L);
+        res.setCache(cache);
+        
+        // stream image back to client
+        InputStream imageData = workflowService.getWorkflowImage(workflowInstanceId);
+        try
+        {
+            FileCopyUtils.copy(imageData, res.getOutputStream());     // both streams are closed
+        }
+        catch (IOException e)
+        {
+            throw new WebScriptException(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Error occurred streaming diagram for workflow instance with id '" + 
+                        workflowInstanceId + "' " + e.getMessage());
+        }
+    }
+}

source/java/org/alfresco/repo/web/scripts/workflow/WorkflowModelBuilder.java

@@ -108,6 +108,7 @@ public class WorkflowModelBuilder
     public static final String TASK_WORKFLOW_INSTANCE_DEFINITION = "definition";
     public static final String TASK_WORKFLOW_INSTANCE_TASKS = "tasks";
     public static final String TASK_WORKFLOW_INSTANCE_DEFINITION_URL = "definitionUrl";
+    public static final String TASK_WORKFLOW_INSTANCE_DIAGRAM_URL = "diagramUrl";
 
     public static final String TASK_WORKFLOW_INSTANCE_INITIATOR_USERNAME = "userName";
     public static final String TASK_WORKFLOW_INSTANCE_INITIATOR_FIRSTNAME = "firstName";
@@ -297,6 +298,11 @@ public class WorkflowModelBuilder
             startTaskId = startTask.getId();
         }
         
+        if (workflowService.hasWorkflowImage(workflowInstance.getId()))
+        {
+            model.put(TASK_WORKFLOW_INSTANCE_DIAGRAM_URL, getDiagramUrl(workflowInstance));
+        }
+        
         model.put(TASK_WORKFLOW_INSTANCE_START_TASK_INSTANCE_ID, startTaskId);
         model.put(TASK_WORKFLOW_INSTANCE_DEFINITION, buildDetailed(workflowInstance.getDefinition()));
 
@@ -627,6 +633,11 @@ public class WorkflowModelBuilder
         return "api/workflow-instances/" + workflowInstance.getId();
     }
     
+    private String getDiagramUrl(WorkflowInstance workflowInstance)
+    {
+        return "api/workflow-instances/" + workflowInstance.getId() + "/diagram";
+    }
+
     private String getAvatarUrl(NodeRef avatarRef)
     {
         return "api/node/" + avatarRef.toString().replace("://", "/") + "/content/thumbnails/avatar";