Source Code of rmitest.RMIGenerator

/*
* Copyright 1999-2004 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 rmitest; 


// import the necessary classes from the java.io package 
import java.io.IOException;
import java.io.StringReader; 


// import the necessary classes from the java.rmi 
import java.rmi.Naming; 
import java.rmi.RemoteException; 
import java.rmi.NotBoundException; 


// import the necessary SAX classes 
import org.xml.sax.InputSource; 
import org.xml.sax.SAXException; 


// import of the classes used from Cocoon 2 
import org.apache.cocoon.ProcessingException; 
import org.apache.cocoon.generation.ComposerGenerator; 


// import of the classes from the 
// Avalon Framework 
import org.apache.avalon.framework.parameters.Parameters; 
import org.apache.avalon.framework.parameters.ParameterException; 
import org.apache.avalon.framework.component.ComponentException; 


// needed for obtaining parser in Cocoon 
import org.apache.excalibur.xml.sax.SAXParser;


/**
 * <p>
 * The <code>RMIGenerator</code> is a generator that reads a String via RMI
 * and generates SAX events. 
 * The RMIGenerator extends the <code>ComposerGenerator</code> class. This is
 * done so we can access the <code>ComponentManager</code> to obtain a
 * <code>SAXParser</code>.
 * </p>
 *
 * <p>
 * The methods invokes to obtain the String via RMI are defined in the 
 * <code>ServerFunctions</code> interface in resides in the same package
 * as this generator. A RMI server application that wants to be able to
 * &quot;feed&quot; XML data to this generator must implement the
 * <code>ServerFunctions</code> interface.
 * </p>
 *
 * <p>
 * <b>Usage:</b>
 * </p>
 *
 * <p>
 * Suppose you declare this generator in your sitemap and name it
 * <code>rmigenerator</code>. A typical example of use is the following:
 * </p>
 *
 * <p>
 * <pre>
 * <code>
 *   &lt;map:match pattern=&quot;rmi/**.xml&quot;&gt;
 *     &lt;map:generate type=&quot;rmigenerator&quot; src=&quot;{1}.xml&quot;&gt;
 *       &lt;!-- host parameter where RMI server is running, REQUIRED --&gt;
 *       &lt;map:parameter name=&quot;host&quot; value=&quot;myhost.com&quot;/&gt;
 *       &lt;!-- bindname parameter, name to which RMI server is bound in remote rmiregistry, REQUIRED --&gt;
 *       &lt;map:paramater name=&quot;bindname&quot; value=&quot;RMIServer&quot;/&gt;
 *       &lt;!-- port parameter, at which port the rmiregistry is running --&gt;
 *       &lt;!-- at the remote host, OPTIONAL --&gt;
 *       &lt;!-- 1099 is the default, this is in fact not really needed --&gt;
 *       &lt;map:parameter name=&quot;port&quot; value=&quot;1099&quot;/&gt;
 *     &lt;map:generate/&gt;
 *     &lt;map:transform src=&quot;somestylesheet.xsl&quot;/&gt;
 *     &lt;map:serialize/&gt;
 *   &lt;/map:match&gt;
 * </code>
 * </pre>
 * </p>
 *
 *
 * @author <a href="mailto:Erwin.Hermans@cs.kuleuven.ac.be">Erwin Hermans</a>
 *         (Student Computer Science Department KULeuven, 2001-2002)
 * @version CVS $Id: RMIGenerator.java,v 1.3 2004/03/06 02:26:14 antonio Exp $
 */
public class RMIGenerator extends ComposerGenerator { 


  /**
   * Generate SAX events based on the parameters and the source specified
   * in the sitemap. If the <code>src</code> attribute is specified, the
   * <code>getResource(String)</code> method is invoked, otherwise the
   * <code>sayHello()</code> is invoked on the remote object.
   *
   */
  public void generate () throws IOException, SAXException, ProcessingException { 
    String host; 
    
    // lookup parameter 'host' 
    try { 
      host = parameters.getParameter("host"); 
      // test if host is not the empty string 
      if (host == "") { 
        throw new ParameterException("The parameter 'host' may not be the empty string"); 
      } 
    } catch (ParameterException pe) { 
      // rethrow as a ProcessingException 
      throw new ProcessingException("Parameter 'host' not specified",pe); 
    }
    
    String bindname;
    
    // lookup parameter 'bindname' 
    try { 
      bindname = parameters.getParameter("bindname"); 
      // test if bindname is not the empty string 
      if (bindname == "") { 
        throw new ParameterException("The parameter 'bindname' may not be the empty string"); 
      }
    } catch (ParameterException pe) { 
      // rethrow as a ProcessingException 
      throw new ProcessingException("Parameter 'bindname' not specified",pe); 
    } 
    
    String port = ""; 
    // lookup parameter 'port' 
    try { 
      port = parameters.getParameter("port"); 
      port = ":" + port; 
    } catch (ParameterException pe) { 
      // reset port to the empty string 
      // port is not required 
      port = ""; 
    }
    
    try {
      ServerFunctions obj = (ServerFunctions)Naming.lookup("//" + host + port + "/" + bindname); 
      String message = "";


      // determine the method to invoke 
      // depending on value of source 
      if (this.source == null) { 
        message = obj.sayHello(); 
      } else { 
        message = obj.getResource(this.source);
      } 
      
      SAXParser parser = null; 
      parser = (SAXParser)this.manager.lookup(SAXParser.ROLE); 
      InputSource inputSource = new InputSource(new StringReader(message)); 
      parser.parse(inputSource,super.xmlConsumer); 
    } catch (NotBoundException nbe) { 
      throw new ProcessingException("Error looking up the RMI application server",nbe); 
    } catch (ComponentException ce) { 
      throw new ProcessingException("Error obtaining a SAXParser",ce); 
    } 
  } 
}
Source Code of rmitest.RMIGenerator

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