| // |
| // ======================================================================== |
| // Copyright (c) 1995-2016 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(); |
| } |
| |
| } |
