/*

 Wotonomy: OpenStep design patterns for pure Java applications.

 Copyright (C) 2000 Intersect Software Corporation

 This library 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 2.1 of the License, or (at your option) any later version.

 This library 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 this library; if not, see http://www.gnu.org

 */

 package net.wotonomy.web.xml;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 import net.wotonomy.foundation.internal.WotonomyException;

 import net.wotonomy.foundation.xml.XMLDecoder;

 import org.xml.sax.SAXException;

 /**

 * An implementation of XMLDecoder that reads objects from 

 * XMLRPC format. 

 * This implementation is not thread-safe, so a new instances

 * should be created to accomodate multiple threads.

 */

 public class XMLRPCDecoder implements XMLDecoder

 {

     XMLRPCDecoderHelper helper = new XMLRPCDecoderHelper();

     /**

     * Decodes an object in XML-RPC format from the specified input stream.

     * @param anInputStream The input stream from which to read.

     * The stream will be read fully.

     * @param aDescription A description to accompany error messages

     * for the stream, typically a file name.

     * @param aURL A URL against which relative references within the

     * XML will be resolved.

     * @return The object that was constructed from the XML content,

     * or null if no object could be constructed.

     */ 

     public Object decode( 

         InputStream anInputStream, String aDescription, URL aURL )

     {

             Object result = null;

         try {

                 SAXParser sparser = SAXParserFactory.newInstance().newSAXParser();

                 sparser.parse(anInputStream,helper,aURL.toExternalForm());

                 result = helper.getResult();

         } catch (ParserConfigurationException e) {

             throw new WotonomyException("Problem in parser configuration", e );

         } catch (IOException e) {

             throw new WotonomyException("IOException thrown while parsing", e );

         } catch (SAXException e) {

             throw new WotonomyException("SAXException thrown while parsing", e );

         }

         helper.reset();

         return result;

     }

     /**

     * Decodes an XML-RPC message from the specified input stream.

     * Stand-alone values not wrapped in "methodCall" or "param"

     * tags will be treated as a response.

     * @param anInputStream The input stream from which to read.

     * The stream will be read fully.

     * @param aReceiver an XMLRPCReceiver that will be invoked with

     * the appropriate method: request, response, or fault.

     */ 

     public void decode( 

         InputStream anInputStream, XMLRPCReceiver aReceiver )

     {

         try

         {

                 SAXParser sparser = SAXParserFactory.newInstance().newSAXParser();

                 sparser.parse(anInputStream,helper);

             if ( helper.isRequest() )

             {

                 aReceiver.request( helper.getMethodName(), helper.getParameters() );

             }

             else

             if ( helper.isFault() )

             {

                 aReceiver.fault( helper.getFaultCode(), helper.getFaultString() );

             }

             else // all else is considered a response

             {

                 aReceiver.response( helper.getResult() );

             }

             } catch (ParserConfigurationException e) {

                 throw new WotonomyException("Problem in parser configuration", e );

             } catch (IOException e) {

                 throw new WotonomyException("IOException thrown while parsing", e );

             } catch (SAXException e) {

                 throw new WotonomyException("SAXException thrown while parsing", e );

         }

         helper.reset();

     }

 }