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From tay...@apache.org
Subject svn commit: r344071 - /portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java
Date Mon, 14 Nov 2005 07:38:21 GMT
Author: taylor
Date: Sun Nov 13 23:38:18 2005
New Revision: 344071

URL: http://svn.apache.org/viewcvs?rev=344071&view=rev
Log:
http://issues.apache.org/jira/browse/JS2-387

Layout pipeline (AJAX), Portlet Placement Manager
base code checked in
still need to integrate into pipeline

Added:
    portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java

Added: portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java
URL: http://svn.apache.org/viewcvs/portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java?rev=344071&view=auto
==============================================================================
--- portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java
(added)
+++ portals/jetspeed-2/trunk/components/portal/src/java/org/apache/jetspeed/ajax/AjaxRequestServiceImpl.java
Sun Nov 13 23:38:18 2005
@@ -0,0 +1,254 @@
+/*
+ * Copyright 2000-2001,2004 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jetspeed.ajax;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.io.StringWriter;
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.ServletOutputStream;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.jetspeed.request.RequestContext;
+import org.apache.velocity.VelocityContext;
+import org.apache.velocity.app.VelocityEngine;
+import org.apache.velocity.context.Context;
+
+/**
+ * 
+ * Provides a generic way to handle a Ajax request/response. Useful for AJAX since
+ * the processing can be broken down into actions and builders
+ */
+public class AjaxRequestServiceImpl implements AjaxRequestService
+{
+
+    protected static final String CONTENT_TYPE = "text/xml";
+
+    protected static final String AJAX_PROCESSOR = "AJAX processor";
+
+    protected static final String DEFAULT_ERROR = "<js><status>failure</status><action>unknown</action></js>";
+
+    // Name of the parameter that will be used to lookup the
+    // command object. Default is action.
+    //
+    // Sample URL:
+    // http://localhost/js?pipeline=layout&action=move
+    //
+    // In this case the parameter "action" is used to find "move"
+    // "move" will be used as the key to lookup the object that will
+    // handle the command
+    protected static final String URL_PARAMETER_NAME = "action";
+
+    /** Logger */
+    protected Log log = LogFactory.getLog(AjaxRequestServiceImpl.class);
+
+    // Objects that are available to execution. These objects must
+    // implement either the Action interface or the Builder interface
+    // or both.
+    // If the Action interface is implemented, then the run method is called
+    // If the Build interface is implemented, then the build methods are called
+    protected Map objects;
+
+    // Used to create the response XML
+    protected VelocityEngine velocityEngine = null;
+
+    // Parameter on the URL that will be used to lookup the object
+    protected String urlParameterName = URL_PARAMETER_NAME;
+
+    // Spring can be used to inject this information
+    public AjaxRequestServiceImpl(Map objects, VelocityEngine velocityEngine)
+    {
+        this.objects = objects;
+        this.velocityEngine = velocityEngine;
+    }
+
+    // Spring can be used to inject this information
+    public AjaxRequestServiceImpl(Map objects, VelocityEngine velocityEngine,
+            String urlParameterName)
+    {
+        this.objects = objects;
+        this.velocityEngine = velocityEngine;
+        this.urlParameterName = urlParameterName;
+    }
+
+    // This is the entry point for this service
+    public void process(RequestContext requestContext) throws AJAXException
+    {
+        // Lookup the object that is to be used
+        String objectKey = requestContext.getRequestParameter(urlParameterName);
+        if (objectKey != null)
+        {
+            // Get the object associated with this key
+            Object object = objects.get(objectKey);
+            if (object != null)
+            {
+                Map resultMap = new HashMap();
+
+                boolean success = true;
+                try
+                {
+                    // Check to see if this object implements the action
+                    // interface
+                    if (object instanceof AjaxAction)
+                    {
+                        success = processAction((AjaxAction) object,
+                                requestContext, resultMap);
+                    }
+                } catch (Exception e)
+                {
+                    success = false;
+                }
+
+                try
+                {
+                    // Check to see if this object implements the builder
+                    // interface
+                    if (object instanceof AjaxBuilder)
+                    {
+                        processBuilder((AjaxBuilder) object, resultMap,
+                                requestContext, success);
+                    }
+                } catch (Exception e)
+                {
+                    // The builder failed, return an error response
+                    buildError(requestContext);
+                }
+            } else
+            {
+                // Log an informational message
+                log.debug("could not find the object named:" + objectKey);
+
+                // Return an error response
+                buildError(requestContext);
+            }
+        } else
+        {
+            // Log an information message
+            log.debug("key not found, could not process");
+
+            // Return an error response
+            buildError(requestContext);
+        }
+    }
+
+    // Process the action if provided
+    protected boolean processAction(AjaxAction action,
+            RequestContext requestContext, Map resultMap)
+            throws Exception
+    {
+        return action.run(requestContext, resultMap);
+    }
+
+    // Process the builder if provided
+    protected void processBuilder(AjaxBuilder builder, Map inputMap,
+            RequestContext requestContext, boolean actionSuccessFlag)
+    {
+        // Response will always be text/xml
+        requestContext.getResponse().setContentType(CONTENT_TYPE);
+
+        try
+        {
+            // Ask the builder to construct the context
+            // Add the input map to the velocity context
+            
+            boolean result = true;
+
+            if (actionSuccessFlag == true)
+            {
+                result = builder.buildContext(requestContext, inputMap);
+            }
+            else
+            {
+                result = builder.buildErrorContext(requestContext, inputMap);
+            }
+            
+            Context context = new VelocityContext(inputMap);
+            
+            // Check to see if we have a valid context
+            if (result)
+            {
+                // Get the name of the template from the builder
+                String templateName = null;
+
+                if (actionSuccessFlag == true)
+                {
+                    templateName = builder.getTemplate();
+                } 
+                else
+                {
+                    templateName = builder.getErrorTemplate();
+                }
+
+                // Get a reader to the velocity template
+                final InputStream templateStream = this.getClass()
+                        .getClassLoader().getResourceAsStream(templateName);
+
+                Reader template = new InputStreamReader(templateStream);
+
+                // The results of the velocity template will be stored here
+                StringWriter stringWriter = new StringWriter();
+
+                // Run the velocity template
+                velocityEngine.evaluate(context, stringWriter,
+                        AJAX_PROCESSOR, template);
+
+                // Get the results from the velocity processing
+                String buffer = stringWriter.getBuffer().toString();
+
+                log.debug("output from AjaxService:" + buffer);
+
+                // Put the response XML on the response object
+                HttpServletResponse response = requestContext.getResponse();
+                ServletOutputStream sos = response.getOutputStream();
+                sos.print(buffer);
+                sos.flush();
+            } 
+            else
+            {
+                log.error("could not create builder context");
+                buildError(requestContext);
+            }
+        } catch (Exception e)
+        {
+            log.error("builder failed", e);
+
+            buildError(requestContext);
+        }
+    }
+
+    // This is the last chance to handle an error to send back to the client
+    // Send back a generic response.  Subclasses may want to override this 
+    // method
+    protected void buildError(RequestContext requestContext)
+    {
+        try
+        {
+            requestContext.getResponse().getOutputStream().print(DEFAULT_ERROR);
+        } 
+        catch (IOException e)
+        {
+            // Not much can be done here, an exception while handling an exception
+            log.error("exception while trying to build an error message", e);
+        }
+    }
+
+}



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