path: root/projects/net.wotonomy.web/src/main/java/net/wotonomy/web/xml/XMLRPCEncoder.java

/*
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.OutputStream;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Array;
import java.text.Format;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import net.wotonomy.foundation.internal.Introspector;
import net.wotonomy.foundation.internal.WotonomyException;
import net.wotonomy.foundation.xml.XMLEncoder;

import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.dom4j.util.NonLazyElement;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

/**
 * An implementation of XMLEncoder that serializes objects into XMLRPC format,
 * which is found at http://xmlrpc.com/spec. We extend that standard only in
 * that we add a "class" attribute to the "value" tag, so that a java-based
 * decoder can more closely reconstruct the original java data structure. The
 * class attribute can be safely ignored by clients. This implementation is not
 * thread-safe, so a new instances should be created to accomodate multiple
 * threads.
 */
public class XMLRPCEncoder implements XMLEncoder {
	public static final String METHODCALL = "methodCall";
	public static final String METHODNAME = "methodName";
	public static final String METHODRESPONSE = "methodResponse";
	public static final String PARAMS = "params";
	public static final String PARAM = "param";
	public static final String FAULT = "fault";
	public static final String FAULTCODE = "faultCode";
	public static final String FAULTSTRING = "faultString";

	public static final String VALUE = "value";
	public static final String CLASS = "class";

	public static final String STRUCT = "struct";
	public static final String MEMBER = "member";
	public static final String NAME = "name";

	public static final String ARRAY = "array";
	public static final String DATA = "data";

	public static final String NIL = "nil";
	public static final String INT = "int";
	public static final String I4 = "i4";
	public static final String BOOLEAN = "boolean";
	public static final String STRING = "string";
	public static final String DOUBLE = "double";
	public static final String DATE = "dateTime.iso8601";
	public static final String BASE64 = "base64";

	public static final String TRUE = "1";
	public static final String FALSE = "0";

	public static final Format DATEFORMAT8601 = new SimpleDateFormat("yyyyMMdd'T'HHmmss");

	/**
	 * Encodes an object to the specified output stream as XML.
	 * 
	 * @param anObject       The object to be serialized to XML format.
	 * @param anOutputStream The output stream to which the object will be written.
	 */
	public void encode(Object anObject, OutputStream anOutputStream) {
		try {

			// XMLWriter writer = new UTF8XMLWriter( anOutputStream );
			RPCXMLWriter writer = new RPCXMLWriter(anOutputStream, OutputFormat.createCompactFormat());
			writeValueToXMLWriter(anObject, writer);
			writer.flush();
		} catch (Exception exc) {
			throw new WotonomyException(exc);
		}
	}

	/**
	 * Encodes a method request in XML-RPC format in a "methodCall" tag, and writes
	 * the XML to the specified output stream. This method only writes XML: the
	 * caller is responsible for generating the appropriate header, if any, which
	 * should set the content type as "text/xml" and the content length as
	 * appropriate. The caller is also responsible for writing the xml version tag.
	 * 
	 * @param aMethodName     The method name to appear in the "methodName" tag.
	 * @param aParameterArray An array of objects, each of which will be encoded as
	 *                        values enclosed in a "param" tag, all of which will be
	 *                        enclosed in a "params" tag.
	 * @param anOutputStream  The stream to which the XML will be written.
	 */
	public void encodeRequest(String aMethodName, Object[] aParameterArray, OutputStream anOutputStream) {
		try {
			RPCXMLWriter writer = new RPCXMLWriter(anOutputStream, OutputFormat.createCompactFormat());
			writer.processingInstruction("xml", "version=\"1.0\" encoding=\"UTF-8\"");
			writer.startElement(METHODCALL);
			writer.startElement(METHODNAME);
			writer.write(aMethodName);
			writer.endElement(METHODNAME);
			writer.startElement(PARAMS);
			for (int i = 0; i < aParameterArray.length; i++) {
				writer.startElement(PARAM);
				writeValueToXMLWriter(aParameterArray[i], writer);
				writer.endElement(PARAM);
			}
			writer.endElement(PARAMS);
			writer.endElement(METHODCALL);
			writer.flush();
		} catch (Exception exc) {
			throw new WotonomyException(exc);
		}

		// TODO: should this return the content-length?
	}

	/**
	 * Encodes a method response in XML-RPC format in a "methodResponse" tag, and
	 * writes the XML to the specified output stream. This method only writes XML:
	 * the caller is responsible for generating the appropriate header, if any,
	 * which should set the content type as "text/xml" and the content length as
	 * appropriate. The caller is also responsible for writing the xml version tag.
	 * 
	 * @param aResult        A object which will be encoded as values enclosed in a
	 *                       "param" tag, all of which will be enclosed in a
	 *                       "params" tag.
	 * @param anOutputStream The stream to which the XML will be written.
	 */
	public void encodeResponse(Object aResult, OutputStream anOutputStream) {
		try {
			RPCXMLWriter writer = new RPCXMLWriter(anOutputStream, OutputFormat.createCompactFormat());
			writer.processingInstruction("xml", "version=\"1.0\" encoding=\"UTF-8\"");
			writer.startElement(METHODRESPONSE);
			writer.startElement(PARAMS);
			writer.startElement(PARAM);
			writeValueToXMLWriter(aResult, writer);
			writer.endElement(PARAM);
			writer.endElement(PARAMS);
			writer.endElement(METHODRESPONSE);
			writer.flush();
		} catch (Exception exc) {
			throw new WotonomyException(exc);
		}

		// TODO: should this return the content-length?
	}

	/**
	 * Encodes a fault response in XML-RPC format in a "methodResponse" tag, and
	 * writes the XML to the specified output stream. This method only writes XML:
	 * the caller is responsible for first generating the appropriate header, if
	 * any, which should set the content type as "text/xml" and the content length
	 * as appropriate. The caller is also responsible for writing the xml version
	 * tag.
	 * 
	 * @param aFaultCode     An application-defined error code.
	 * @param aFaultString   A human-readable error description.
	 * @param anOutputStream The stream to which the XML will be written.
	 */
	public void encodeFault(int aFaultCode, String aFaultString, OutputStream anOutputStream) {
		try {
			RPCXMLWriter writer = new RPCXMLWriter(anOutputStream, OutputFormat.createCompactFormat());
			writer.processingInstruction("xml", "version=\"1.0\"");
			writer.startElement(METHODRESPONSE);
			writer.startElement(FAULT);
			writer.startElement(VALUE);
			writer.startElement(STRUCT);

			writer.startElement(MEMBER);
			writer.startElement(NAME);
			writer.write(FAULTCODE);
			writer.endElement(NAME);
			writer.startElement(VALUE);
			writer.startElement(INT);
			writer.write(new Integer(aFaultCode).toString());
			writer.endElement(INT);
			writer.endElement(VALUE);
			writer.endElement(MEMBER);

			writer.startElement(MEMBER);
			writer.startElement(NAME);
			writer.write(FAULTSTRING);
			writer.endElement(NAME);
			writer.startElement(VALUE);
			writer.startElement(STRING);
			writer.write(aFaultString);
			writer.endElement(STRING);
			writer.endElement(VALUE);
			writer.endElement(MEMBER);

			writer.endElement(STRUCT);
			writer.endElement(VALUE);
			writer.endElement(FAULT);
			writer.endElement(METHODRESPONSE);
			writer.flush();
		} catch (Exception exc) {
			throw new WotonomyException(exc);
		}

		// TODO: should this return the content-length?
	}

	/**
	 * Performs the actual writing of the file to XML.
	 */
	private void writeValueToXMLWriter(Object anObject, RPCXMLWriter writer) {
		try {

			if (anObject == null) {
				writer.startElement(VALUE);
				// write nil for null
				Element nill = new NonLazyElement(NIL);
				writer.write(nill);
			} else if (anObject instanceof Collection) {
				// write class so we can restore if possible
				AttributesImpl a = new AttributesImpl();
				a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

				writer.startElement(VALUE, a);

				// write items in the order we get them from the iterator

				writer.startElement(ARRAY);
				writer.startElement(DATA);
				Iterator it = ((Collection) anObject).iterator();
				while (it.hasNext()) {
					writeValueToXMLWriter(it.next(), writer);
				}
				writer.endElement(DATA);
				writer.endElement(ARRAY);

			} else if (anObject instanceof Map) {
				AttributesImpl a = new AttributesImpl();
				a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

				writer.startElement(VALUE, a);

				// write items in the order we get them from the iterator
				// FIXME: The method-based properties are being ignored!

				Map.Entry entry;
				writer.startElement(STRUCT);
				writer.startElement(MEMBER);
				Iterator it = ((Map) anObject).entrySet().iterator();
				while (it.hasNext()) {
					entry = (Map.Entry) it.next();
					writer.startElement(NAME);
					writeValueToXMLWriter(entry.getKey(), writer);
					writer.endElement(NAME);
					writeValueToXMLWriter(entry.getValue(), writer);
				}
				writer.endElement(MEMBER);
				writer.endElement(STRUCT);
			} else // not a collection
			{
				// check for primitive types
				if (anObject instanceof String) {
					writer.startElement(VALUE);

					writer.startElement(STRING);
					writer.write(anObject.toString());
					writer.endElement(STRING);
				} else if (anObject instanceof StringBuffer) {
					// write class so we can restore if possible
					AttributesImpl a = new AttributesImpl();
					a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

					writer.startElement(VALUE, a);

					writer.startElement(STRING);
					writer.write(anObject.toString());
					writer.endElement(STRING);
				} else if (anObject instanceof Number) {
					// write class so we can restore if possible
					AttributesImpl a = new AttributesImpl();
					a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

					writer.startElement(VALUE, a);

					if ((anObject instanceof Double) || (anObject instanceof Float)) {
						writer.startElement(DOUBLE);
						writer.write(anObject.toString());
						writer.endElement(DOUBLE);
					} else {
						writer.startElement(INT);
						writer.write(anObject.toString());
						writer.endElement(INT);
					}
				} else if (anObject instanceof Date) {
					// write class so we can restore if possible
					AttributesImpl a = new AttributesImpl();
					a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

					writer.startElement(VALUE, a);

					writer.startElement(DATE);
					writer.write(DATEFORMAT8601.format(anObject));
					writer.endElement(DATE);
				} else if (anObject instanceof Boolean) {
					writer.startElement(BOOLEAN);
					if (((Boolean) anObject).booleanValue()) {
						writer.write("1");
					} else {
						writer.write("0");
					}
					writer.endElement(BOOLEAN);
				} else if (anObject.getClass().isArray()) {
					// write class so we can restore if possible
					AttributesImpl a = new AttributesImpl();
					a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

					writer.startElement(VALUE, a);

					writer.startElement(ARRAY);
					writer.startElement(DATA);

					int length = Array.getLength(anObject);
					for (int i = 0; i < length; i++) {
						writeValueToXMLWriter(Array.get(anObject, i), writer);
					}

					writer.endElement(DATA);
					writer.endElement(ARRAY);
				} else // not primitive or collection, treat as struct
				{
					// write class so we can restore if possible
					AttributesImpl a = new AttributesImpl();
					a.addAttribute(null, CLASS, null, null, anObject.getClass().getName());

					writer.startElement(VALUE, a);

					List readProperties = new ArrayList();
					String[] read = Introspector.getReadPropertiesForObject(anObject);
					for (int i = 0; i < read.length; i++) {
						readProperties.add(read[i]);
					}

					List properties = new ArrayList();
					String[] write = Introspector.getWritePropertiesForObject(anObject);
					for (int i = 0; i < write.length; i++) {
						properties.add(write[i]);
					}

					// only use readable properties
					properties.retainAll(readProperties);

//                if ( properties.size() > 0 )
//                {
					String key;
					Object value;
					Iterator it = properties.iterator();
					writer.startElement(STRUCT);
					while (it.hasNext()) {
						key = (String) it.next();
						value = Introspector.get(anObject, key);

						writer.startElement(MEMBER);
						writer.startElement(NAME);
						writer.write(key);
						writer.endElement(NAME);
						writeValueToXMLWriter(value, writer);
						writer.endElement(MEMBER);
					}
					writer.endElement(STRUCT);
					/*
					 * } else // no properties - write a converted string { writer.startElement(
					 * STRING ); Object converted = ValueConverter.convertObjectToClass( anObject,
					 * String.class ); if ( converted != null ) { writer.write( converted.toString()
					 * ); } else { writer.write( anObject.toString() ); } writer.endElement( STRING
					 * ); }
					 */
				}
			}

			writer.endElement(VALUE);
		} catch (Exception exc) {
			System.err.println("XMLFileSoup.writeValueToXMLWriter: " + exc);
			exc.printStackTrace();
		}

	}
	/*
	 * public static void main( String[] argv ) { System.out.println( "<test>" );
	 * XMLRPCEncoder encoder = new XMLRPCEncoder(); encoder.encodeRequest(
	 * "systemObject.test", new Object[] { new net.wotonomy.test.TestObject(), new
	 * net.wotonomy.test.TestObject(), new net.wotonomy.test.TestObject() },
	 * System.out ); System.out.println(); System.out.println();
	 * encoder.encodeResponse( new net.wotonomy.test.TestObject(), System.out );
	 * System.out.println(); System.out.println(); encoder.encodeFault( -1,
	 * "This is a fault.", System.out ); System.out.println(); System.out.println();
	 * System.out.println( "</test>" ); }
	 */

	private class RPCXMLWriter extends XMLWriter {

		public RPCXMLWriter(OutputStream arg0, OutputFormat arg1) throws UnsupportedEncodingException {
			super(arg0, arg1);
		}

		public void endElement(String localname) throws SAXException {
			super.endElement(null, localname, null);
		}

		public void startElement(String localname) throws SAXException {
			this.startElement(localname, null);
		}

		public void startElement(String localname, Attributes attributes) throws SAXException {
			this.startElement(null, localname, null, attributes);
		}

	}

}