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/*
* This file is part of the Echo Web Application Framework (hereinafter "Echo").
* Copyright (C) 2002-2009 NextApp, Inc.
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
package nextapp.echo2.webrender.service;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
import nextapp.echo2.webrender.ClientAnalyzerProcessor;
import nextapp.echo2.webrender.Connection;
import nextapp.echo2.webrender.ContentType;
import nextapp.echo2.webrender.ServerMessage;
import nextapp.echo2.webrender.Service;
import nextapp.echo2.webrender.UserInstance;
import nextapp.echo2.webrender.UserInstanceUpdateManager;
import nextapp.echo2.webrender.servermessage.ClientConfigurationUpdate;
import nextapp.echo2.webrender.servermessage.ClientPropertiesStore;
import nextapp.echo2.webrender.servermessage.ServerDelayMessageUpdate;
import nextapp.echo2.webrender.util.DomUtil;
/**
* A service which synchronizes the state of the client with that of the server.
* Requests made to this service are in the form of "ClientMessage" XML
* documents which describe the user's actions since the last synchronization,
* e.g., the input typed into text fields and the action taken (e.g., a button
* press) which caused the server interaction. The service parses this XML input
* from the client and performs updates to the server state of the application.
* Once the input has been processed by the server application, an output
* "ServerMessage" containing instructions to update the client state is
* generated as a response.
*/
public abstract class SynchronizeService
implements Service {
/**
* An interface describing a ClientMessage MessagePart Processor.
* Implementations registered with the
* registerClientMessagePartProcessor() method will have
* their process() methods invoked when a matching
* message part is provided in a ClientMessage.
*/
public static interface ClientMessagePartProcessor {
/**
* Returns the name of the ClientMessagePartProcessor.
* The processor will be invoked when a message part with its name
* is found within the ClientMessage.
*
* @return the name of the processor
*/
public String getName();
/**
* Processes a MessagePart of a ClientMessage
*
* @param userInstance the relevant UserInstance
* @param messagePartElement the message part element
* to process
*/
public void process(UserInstance userInstance, Element messagePartElement);
}
/**
* Service identifier.
*/
public static final String SERVICE_ID = "Echo.Synchronize";
/**
* Map containing registered ClientMessagePartProcessors.
*/
private Map clientMessagePartProcessorMap = new HashMap();
/**
* Creates a new SynchronizeService.
*/
public SynchronizeService() {
super();
registerClientMessagePartProcessor(new ClientAnalyzerProcessor());
}
/**
* Trims an XML InputStream to work around the issue
* of the XML parser crashing on trailing whitespace. This issue is present
* with requests from Konqueror/KHTML browsers.
*
* @param in the InputStream
* @param characterEncoding the character encoding of the stream
* @return a cleaned version of the stream, as a
* ByteArrayInputStream.
*/
private InputStream cleanXmlInputStream(InputStream in, String characterEncoding)
throws IOException{
ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
byte[] buffer = new byte[4096];
int bytesRead = 0;
try {
do {
bytesRead = in.read(buffer);
if (bytesRead > 0) {
byteOut.write(buffer, 0, bytesRead);
}
} while (bytesRead > 0);
} finally {
if (in != null) { try { in.close(); } catch (IOException ex) { } }
}
in.close();
byte[] data = byteOut.toByteArray();
data = new String(data, characterEncoding).trim().getBytes(characterEncoding);
return new ByteArrayInputStream(data);
}
/**
* @see nextapp.echo2.webrender.Service#getId()
*/
public String getId() {
return SERVICE_ID;
}
/**
* @see nextapp.echo2.webrender.Service#getVersion()
*/
public int getVersion() {
return DO_NOT_CACHE;
}
/**
* Generates a DOM representation of the XML input POSTed to this service.
*
* @param conn the relevant Connection
* @return a DOM representation of the POSTed XML input
* @throws IOException if the input is invalid
*/
private Document parseRequestDocument(Connection conn)
throws IOException {
HttpServletRequest request = conn.getRequest();
InputStream in = null;
try {
String userAgent = conn.getRequest().getHeader("user-agent");
if (userAgent != null && userAgent.indexOf("onqueror") != -1) {
// Invoke XML 'cleaner', but only for user agents that contain the string "onqueror",
// such as Konqueror, for example.
in = cleanXmlInputStream(request.getInputStream(), conn.getUserInstance().getCharacterEncoding());
} else {
in = request.getInputStream();
}
return DomUtil.getDocumentBuilder().parse(in);
} catch (SAXException ex) {
throw new IOException("Provided InputStream cannot be parsed: " + ex);
} catch (IOException ex) {
throw new IOException("Provided InputStream cannot be parsed: " + ex);
} finally {
if (in != null) { try { in.close(); } catch (IOException ex) { } }
}
}
/**
* Processes a "ClientMessage" XML document containing application UI state
* change information from the client. This method will parse the
* message parts of the ClientMessage and invoke the
* ClientMessagePartProcessors registered to process them.
*
* @param conn the relevant Connection
* @param clientMessageDocument the ClientMessage XML document to process
* @see ClientMessagePartProcessor
*/
protected void processClientMessage(Connection conn, Document clientMessageDocument) {
UserInstance userInstance = conn.getUserInstance();
Element[] messageParts = DomUtil.getChildElementsByTagName(clientMessageDocument.getDocumentElement(),
"message-part");
for (int i = 0; i < messageParts.length; ++i) {
ClientMessagePartProcessor processor =
(ClientMessagePartProcessor) clientMessagePartProcessorMap.get(messageParts[i].getAttribute("processor"));
if (processor == null) {
throw new RuntimeException("Invalid processor name \"" + messageParts[i].getAttribute("processor") + "\".");
}
processor.process(userInstance, messageParts[i]);
}
}
/**
* Registers a ClientMessagePartProcessor to handle a
* specific type of message part.
*
* @param processor the ClientMessagePartProcessor to
* register
* @throws IllegalStateException if a processor with the same name is
* already registered
*/
protected void registerClientMessagePartProcessor(ClientMessagePartProcessor processor) {
if (clientMessagePartProcessorMap.containsKey(processor.getName())) {
throw new IllegalStateException("Processor already registered with name \"" + processor.getName() + "\".");
}
clientMessagePartProcessorMap.put(processor.getName(), processor);
}
/**
* Renders a ServerMessage in response to the initial
* synchronization.
*
* @param conn the relevant Connection
* @param clientMessageDocument the ClientMessage XML document
* @return the generated ServerMessage
*/
protected abstract ServerMessage renderInit(Connection conn, Document clientMessageDocument);
/**
* Renders a ServerMessage in response to a synchronization
* other than the initial synchronization.
*
* @param conn the relevant Connection
* @param clientMessageDocument the ClientMessage XML document
* @return the generated ServerMessage
*/
protected abstract ServerMessage renderUpdate(Connection conn, Document clientMessageDocument);
/**
* @see nextapp.echo2.webrender.Service#service(nextapp.echo2.webrender.Connection)
*/
public void service(Connection conn)
throws IOException {
UserInstance userInstance = conn.getUserInstance();
synchronized(userInstance) {
Document clientMessageDocument = parseRequestDocument(conn);
String messageType = clientMessageDocument.getDocumentElement().getAttribute("type");
ServerMessage serverMessage;
if ("initialize".equals(messageType)) {
serverMessage = renderInit(conn, clientMessageDocument);
ClientPropertiesStore.renderStoreDirective(serverMessage, userInstance.getClientProperties());
ClientConfigurationUpdate.renderUpdateDirective(serverMessage, userInstance.getClientConfiguration());
ServerDelayMessageUpdate.renderUpdateDirective(serverMessage, userInstance.getServerDelayMessage());
// Add "test attribute" used by ClientEngine to determine if browser is correctly (un)escaping
// attribute values. Safari does not do this correctly and a workaround is thus employed if such
// bugs are detected.
serverMessage.getDocument().getDocumentElement().setAttribute("xml-attr-test", "x&y");
} else {
serverMessage = renderUpdate(conn, clientMessageDocument);
processUserInstanceUpdates(userInstance, serverMessage);
}
serverMessage.setTransactionId(userInstance.getNextTransactionId());
conn.setContentType(ContentType.TEXT_XML);
serverMessage.render(conn.getWriter());
}
}
/**
* Renders updates to UserInstance properties.
*
* @param userInstance the relevant UserInstance
* @param serverMessage the ServerMessage containing the updates
*/
private void processUserInstanceUpdates(UserInstance userInstance, ServerMessage serverMessage) {
UserInstanceUpdateManager updateManager = userInstance.getUserInstanceUpdateManager();
String[] updatedPropertyNames = updateManager.getPropertyUpdateNames();
for (int i = 0; i < updatedPropertyNames.length; ++i) {
if (UserInstance.PROPERTY_CLIENT_CONFIGURATION.equals(updatedPropertyNames[i])) {
ClientConfigurationUpdate.renderUpdateDirective(serverMessage, userInstance.getClientConfiguration());
} else if (UserInstance.PROPERTY_SERVER_DELAY_MESSAGE.equals(updatedPropertyNames[i])) {
ServerDelayMessageUpdate.renderUpdateDirective(serverMessage, userInstance.getServerDelayMessage());
}
}
updateManager.purge();
}
}