//
// ========================================================================
// Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.rhttp.gateway;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jetty.http.MimeTypes;
import org.eclipse.jetty.rhttp.client.RHTTPClient;
import org.eclipse.jetty.rhttp.client.RHTTPRequest;
import org.eclipse.jetty.rhttp.client.RHTTPResponse;
import org.eclipse.jetty.server.Connector;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.HandlerCollection;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/**
* <p>The gateway server is a server component that acts as intermediary between
* <em>external clients</em> which perform requests for resources, and the
* <em>resource providers</em>.</p>
* <p>The particularity of the gateway server is that the resource providers
* connect to the gateway using a comet protocol. <br />
* The comet procotol functionality is implemented by a gateway client. <br />
* This is quite different from a normal proxy server where it is the proxy that
* connects to the resource providers.</p>
* <p>Schematically, this is how the gateway server works:</p>
* <pre>
* External Client Gateway Server Gateway Client Resource Provider
* | |
* | <-- comet req. 1 --- |
* | --- ext. req. 1 --> | |
* | | --- comet res. 1 --> |
* | | <-- comet req. 2 --- |
* | | --- ext. req. 1 --> |
* |
* | | <-- ext. res. 1 --- |
* | | <-- ext. res. 1 --- |
* | <-- ext. res. 1 --- |
*
* | --- ext. req. 2 --> |
* | | --- comet res. 2 --> |
* . . .
* </pre>
* <p>The gateway server is made of two servlets:
* <ul>
* <li>the external servlet, that handles external requests</li>
* <li>the gateway servlet, that handles the communication with the gateway client</li>
* </ul>
* </p>
* <p>External requests are suspended using Jetty continuations until a response for
* that request arrives from the resource provider, or a
* {@link #getExternalTimeout() configurable timeout} expires. <br />
* Comet requests made by the gateway client also expires after a (different)
* {@link #getGatewayTimeout() configurable timeout}.</p>
* <p>External requests are packed into {@link RHTTPRequest} objects, converted into an
* opaque byte array and sent as the body of the comet reponse to the gateway
* {@link RHTTPClient}.</p>
* <p>The gateway client uses a notification mechanism to alert listeners interested
* in external requests that have been forwarded through the gateway. It is up to the
* listeners to connect to the resource provider however they like.</p>
* <p>When the gateway client receives a response from the resource provider, it packs
* the response into a {@link RHTTPResponse} object, converts it into an opaque byte array
* and sends it as the body of a normal HTTP request to the gateway server.</p>
* <p>It is possible to connect more than one gateway client to a gateway server; each
* gateway client is identified by a unique <em>targetId</em>. <br />
* External requests must specify a targetId that allows the gateway server to forward
* the requests to the specific gateway client; how the targetId is retrieved from an
* external request is handled by {@link TargetIdRetriever} implementations.</p>
*
* @version $Revision$ $Date$
*/
public class GatewayServer extends Server
{
public final static String DFT_EXT_PATH="/gw";
public final static String DFT_CONNECT_PATH="/__rhttp";
private final Logger logger = Log.getLogger(getClass().toString());
private final Gateway gateway;
private final ServletHolder externalServletHolder;
private final ServletHolder connectorServletHolder;
private final ServletContextHandler context;
public GatewayServer()
{
this("",DFT_EXT_PATH,DFT_CONNECT_PATH,new StandardTargetIdRetriever());
}
public GatewayServer(String contextPath, String externalServletPath,String gatewayServletPath, TargetIdRetriever targetIdRetriever)
{
HandlerCollection handlers = new HandlerCollection();
setHandler(handlers);
context = new ServletContextHandler(handlers, contextPath, ServletContextHandler.SESSIONS);
// Setup the gateway
gateway = createGateway();
// Setup external servlet
ExternalServlet externalServlet = new ExternalServlet(gateway, targetIdRetriever);
externalServletHolder = new ServletHolder(externalServlet);
context.addServlet(externalServletHolder, externalServletPath + "/*");
logger.debug("External servlet mapped to {}/*", externalServletPath);
// Setup gateway servlet
ConnectorServlet gatewayServlet = new ConnectorServlet(gateway);
connectorServletHolder = new ServletHolder(gatewayServlet);
connectorServletHolder.setInitParameter("clientTimeout", "15000");
context.addServlet(connectorServletHolder, gatewayServletPath + "/*");
logger.debug("Gateway servlet mapped to {}/*", gatewayServletPath);
}
/**
* Creates and configures a {@link Gateway} object.
* @return the newly created and configured Gateway object.
*/
protected Gateway createGateway()
{
StandardGateway gateway = new StandardGateway();
return gateway;
}
public ServletContextHandler getContext()
{
return context;
}
public Gateway getGateway()
{
return gateway;
}
public ServletHolder getExternalServlet()
{
return externalServletHolder;
}
public ServletHolder getConnectorServlet()
{
return connectorServletHolder;
}
public void setTargetIdRetriever(TargetIdRetriever retriever)
{
((ExternalServlet)externalServletHolder.getServletInstance()).setTargetIdRetriever(retriever);
}
public TargetIdRetriever getTargetIdRetriever()
{
return ((ExternalServlet)externalServletHolder.getServletInstance()).getTargetIdRetriever();
}
}