EnginePrivate


1   /*
2    * Copyright 2005 Joe Walker
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.directwebremoting.extend;
17  
18  import java.io.IOException  ;
19  
20  import org.directwebremoting.ScriptBuffer;
21  import org.directwebremoting.dwrp.ProtocolConstants;
22  import org.directwebremoting.impl.DefaultRemoter;
23  import org.directwebremoting.proxy.ScriptProxy;
24  import org.directwebremoting.util.JavascriptUtil;
25  import org.directwebremoting.util.Logger;
26  
27  /**
28   * An abstraction of the DWREngine Javascript class for use by
29   * {@link org.directwebremoting.dwrp.BaseCallMarshaller},
30   * {@link org.directwebremoting.dwrp.PollHandler} and a few others that need
31   * to call internal functions in engine.js
32   * @author Joe Walker [joe at getahead dot ltd dot uk]
33   */
34  public class EnginePrivate extends ScriptProxy
35  {
36      /**
37       * Call the dwr.engine._remoteHandleResponse() in the browser
38       * @param conduit The browser pipe to write to
39       * @param batchId The identifier of the batch that we are handling a response for
40       * @param callId The identifier of the call that we are handling a response for
41       * @param data The data to pass to the callback function
42       * @throws IOException If writing fails.
43       * @throws MarshallException If objects in the script can not be marshalled
44       */
45      public static void remoteHandleCallback(ScriptConduit conduit, String   batchId, String   callId, Object   data) throws IOException  , MarshallException
46      {
47          ScriptBuffer script = new ScriptBuffer();
48          script.appendScript("dwr.engine._remoteHandleCallback(\'")
49                .appendScript(batchId)
50                .appendScript("\',\'")
51                .appendScript(callId)
52                .appendScript("\',")
53                .appendData(data)
54                .appendScript(");");
55  
56          conduit.addScript(script);
57      }
58  
59      /**
60       * Call the dwr.engine._remoteHandleException() in the browser
61       * @param conduit The browser pipe to write to
62       * @param batchId The identifier of the batch that we are handling a response for
63       * @param callId The id of the call we are replying to
64       * @param ex The exception to throw on the remote end
65       * @throws IOException If writing fails.
66       */
67      public static void remoteHandleMarshallException(ScriptConduit conduit, String   batchId, String   callId, MarshallException ex) throws IOException  
68      {
69          try
70          {
71              ScriptBuffer script = new ScriptBuffer();
72              script.appendScript("dwr.engine._remoteHandleException(\'")
73                    .appendScript(batchId)
74                    .appendScript("\',\'")
75                    .appendScript(callId)
76                    .appendScript("\',")
77                    .appendData(ex)
78                    .appendScript(");");
79  
80              conduit.addScript(script);
81          }
82          catch (MarshallException mex)
83          {
84              ScriptBuffer script = new ScriptBuffer();
85              script.appendScript("dwr.engine._remoteHandleException(\'")
86                    .appendScript(batchId)
87                    .appendScript("\',\'")
88                    .appendScript(callId)
89                    .appendScript("\',")
90                    .appendData(ex)
91                    .appendScript(");");
92  
93              addScriptWithoutException(conduit, script);
94          }
95      }
96  
97      /**
98       * Call the dwr.engine._remoteHandleException() in the browser
99       * @param conduit The browser pipe to write to
100      * @param batchId The identifier of the batch that we are handling a response for
101      * @param callId The id of the call we are replying to
102      * @param ex The exception to throw on the remote end
103      * @throws IOException If writing fails.
104      */
105     public static void remoteHandleException(ScriptConduit conduit, String   batchId, String   callId, Throwable   ex) throws IOException  
106     {
107         try
108         {
109             ScriptBuffer script = new ScriptBuffer();
110             script.appendScript("dwr.engine._remoteHandleException(\'")
111                   .appendScript(batchId)
112                   .appendScript("\',\'")
113                   .appendScript(callId)
114                   .appendScript("\',")
115                   .appendData(ex)
116                   .appendScript(");");
117 
118             conduit.addScript(script);
119         }
120         catch (MarshallException mex)
121         {
122             ScriptBuffer script = new ScriptBuffer();
123             script.appendScript("dwr.engine._remoteHandleException(\'")
124                   .appendScript(batchId)
125                   .appendScript("\',\'")
126                   .appendScript(callId)
127                   .appendScript("\',")
128                   .appendData(ex)
129                   .appendScript(");");
130 
131             addScriptWithoutException(conduit, script);
132         }
133     }
134 
135     /**
136      * Call the dwr.engine._remoteHandleServerException() in the browser
137      * @param batchId The identifier of the batch that we are handling a response for
138      * @param ex The execption from which we make a reply
139      * @return The string that calls dwr.engine._remoteHandleServerException()
140      */
141     public static String   getRemoteHandleBatchExceptionScript(String   batchId, Exception   ex)
142     {
143         StringBuffer   reply = new StringBuffer  ();
144 
145         String   output = JavascriptUtil.escapeJavaScript(ex.getMessage());
146         String   params = "{ name:'" + ex.getClass().getName() + "', message:'" + output + "' }";
147         if (batchId != null)
148         {
149             params += ", '" + batchId + "'";
150         }
151 
152         reply.append(ProtocolConstants.SCRIPT_CALL_REPLY).append("\r\n");
153         reply.append("if (window.dwr) dwr.engine._remoteHandleBatchException(").append(params).append(");\r\n");
154         reply.append("else if (window.parent.dwr) window.parent.dwr.engine._remoteHandleBatchException(").append(params).append(");\r\n");
155 
156         return reply.toString();
157     }
158 
159     /**
160      * Call the dwr.engine._remotePollCometDisabled() in the browser
161      * @param batchId The identifier of the batch that we are handling a response for
162      * @return The string that calls dwr.engine._remoteHandleServerException()
163      */
164     public static String   getRemotePollCometDisabledScript(String   batchId)
165     {
166         StringBuffer   reply = new StringBuffer  ();
167 
168         String   params = "{ name:'dwr.engine.pollAndCometDisabled', message:'Polling and Comet are disabled. See the server logs.' }";
169         if (batchId != null)
170         {
171             params += ", '" + batchId + "'";
172         }
173 
174         reply.append(ProtocolConstants.SCRIPT_CALL_REPLY).append("\r\n");
175         reply.append("if (window.dwr) dwr.engine._remotePollCometDisabled(").append(params).append(");\r\n");
176         reply.append("else if (window.parent.dwr) window.parent.dwr.engine._remotePollCometDisabled(").append(params).append(");\r\n");
177 
178         return reply.toString();
179     }
180 
181     /**
182      * Take an XML string, and convert it into some Javascript that when
183      * executed will return a DOM object that represents the same XML object
184      * @param xml The XML string to convert
185      * @return The Javascript
186      */
187     public static String   xmlStringToJavascriptDom(String   xml)
188     {
189         String   xmlout = JavascriptUtil.escapeJavaScript(xml);
190         return "dwr.engine._unserializeDocument(\"" + xmlout + "\")";
191     }
192 
193     /**
194      * Get a string which will initialize a dwr.engine object
195      * @return A dwr.engine init script
196      */
197     public static String   getEngineInitScript()
198     {
199         return "// Provide a default path to dwr.engine\n" +
200                "if (dwr == null) var dwr = {};\n" +
201                "if (dwr.engine == null) dwr.engine = {};\n" +
202                "if (DWREngine == null) var DWREngine = dwr.engine;\n" +
203                '\n';
204     }
205 
206     /**
207      * {@link DefaultRemoter} needs to know the name of the execute function
208      * @return The execute function name
209      */
210     public static String   getExecuteFunctionName()
211     {
212         return "dwr.engine._execute";
213     }
214 
215     /**
216      * A script to send at the beginning of an iframe response
217      * @param batchId The id of the current batch
218      * @param useWindowParent Will the exec happen from a child iframe which is
219      * the case for normal iframe based calls, or from the main window, which is
220      * the case for iframe streamed polling.
221      * @return A script to init the environment
222      */
223     public static String   remoteBeginIFrameResponse(String   batchId, boolean useWindowParent)
224     {
225         String   prefix = "";
226         if (useWindowParent)
227         {
228             prefix = "window.parent.";
229         }
230 
231         return prefix + "dwr.engine._remoteBeginIFrameResponse(this.frameElement"+(batchId == null?"":", '" + batchId+"'") + ");";
232     }
233 
234     /**
235      * A script to send at the end of an iframe response
236      * @param batchId The id of the current batch
237      * @param useWindowParent Will the exec happen from a child iframe which is
238      * the case for normal iframe based calls, or from the main window, which is
239      * the case for iframe streamed polling.
240      * @return A script to tidy up the environment
241      */
242     public static String   remoteEndIFrameResponse(String   batchId, boolean useWindowParent)
243     {
244         String   prefix = "";
245         if (useWindowParent)
246         {
247             prefix = "window.parent.";
248         }
249 
250         return prefix + "dwr.engine._remoteEndIFrameResponse("+(batchId == null?"":"'" + batchId+"'")+");";
251     }
252 
253     /**
254      * Prepare a script for execution in an iframe environment
255      * @param script The script to modify
256      * @return The modified script
257      */
258     public static String   remoteEval(String   script)
259     {
260         return "window.parent.dwr.engine._eval(\"" + JavascriptUtil.escapeJavaScript(script) + "\");";
261     }
262 
263     /**
264      * Calling {@link ScriptConduit#addScript(ScriptBuffer)} throws a
265      * {@link MarshallException} which we want to ignore since it almost
266      * certainly can't happen for real.
267      * @param conduit The browser pipe to write to
268      * @param script The buffer to add to the current {@link ScriptConduit}
269      * @throws IOException If the write process fails
270      */
271     private static void addScriptWithoutException(ScriptConduit conduit, ScriptBuffer script) throws IOException  
272     {
273         try
274         {
275             conduit.addScript(script);
276         }
277         catch (MarshallException ex)
278         {
279             log.warn("This exception can't happen", ex);
280         }
281     }
282 
283     /**
284      * The log stream
285      */
286     private static final Logger log = Logger.getLogger(EnginePrivate.class);
287 }
288
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