PC Professionell 2004 December/PCpro_2004_12.ISO/files/webserver/xampp/xampp-cocoon-addon-1.4.9-installer.exe/RMIGenerator.java

Java Source | 2004-07-12 | 5.7 KB | 169 lines

/*
* 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
 * "feed" 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>
 *   <map:match pattern="rmi/**.xml">
 *     <map:generate type="rmigenerator" src="{1}.xml">
 *       <!-- host parameter where RMI server is running, REQUIRED -->
 *       <map:parameter name="host" value="myhost.com"/>
 *       <!-- bindname parameter, name to which RMI server is bound in remote rmiregistry, REQUIRED -->
 *       <map:paramater name="bindname" value="RMIServer"/>
 *       <!-- port parameter, at which port the rmiregistry is running -->
 *       <!-- at the remote host, OPTIONAL -->
 *       <!-- 1099 is the default, this is in fact not really needed -->
 *       <map:parameter name="port" value="1099"/>
 *     <map:generate/>
 *     <map:transform src="somestylesheet.xsl"/>
 *     <map:serialize/>
 *   </map:match>
 * </code>
 * </pre>
 * </p>
 *
 *
 * @author <a href="mailto:[e-mail]">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);
        }
    }
}