org.jboss.web.loadbalancer.LoadbalancerServlet.java Source code

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Here is the source code for org.jboss.web.loadbalancer.LoadbalancerServlet.java

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/*
 * JBoss, the OpenSource WebOS
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */
package org.jboss.web.loadbalancer;

import java.io.IOException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.httpclient.HttpMethod;
import org.jboss.logging.Logger;
import org.jboss.web.loadbalancer.scheduler.NoHostAvailableException;
import org.jboss.web.loadbalancer.util.Constants;
import org.jboss.mx.util.MBeanProxyExt;
import javax.management.MalformedObjectNameException;

/**
 * A servlet that does the job of a reverse proxy.
 *
 * @author Thomas Peuss <jboss@peuss.de>
 * @version $Revision: 1.4.2.1 $
 */
public class LoadbalancerServlet extends HttpServlet {
    protected static Logger log = Logger.getLogger(LoadbalancerServlet.class);

    protected String loadbalancerName;
    protected LoadbalancerServiceMBean loadbalancer;

    protected void handleRequest(HttpServletRequest request, HttpServletResponse response, int requestMethod)
            throws ServletException, IOException {
        HttpMethod method = null;

        initLoadbalancerDelegate();

        // get target host from scheduler
        try {
            method = loadbalancer.createMethod(request, response, requestMethod);
        } catch (NoHostAvailableException nhae) {
            log.error("We have no host to schedule request - giving up");
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, nhae.getMessage());
            return;
        }
        loadbalancer.addRequestData(request, method);

        // do handle the request
        loadbalancer.handleRequest(request, response, method);
    }

    /* Handler for GET-requests
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_GET);
    }

    /* Handler for POST-requests
     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_POST);
    }

    /* Handler for DELETE-requests
     * @see javax.servlet.http.HttpServlet#doDelete(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doDelete(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_DELETE);
    }

    /* Handler for HEAD-requests
     * @see javax.servlet.http.HttpServlet#doHead(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doHead(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_HEAD);
    }

    /* Handler for OPTIONS-requests
     * @see javax.servlet.http.HttpServlet#doOptions(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doOptions(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_OPTIONS);
    }

    /* Handler for PUT-requests
     * @see javax.servlet.http.HttpServlet#doPut(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doPut(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        handleRequest(request, response, Constants.HTTP_METHOD_PUT);
    }

    /* Servlet initialisation.
     * @see javax.servlet.Servlet#init(javax.servlet.ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        loadbalancerName = config.getInitParameter("loadbalancer-service-name");

        log.debug("Servlet init ready");
    }

    /* Servlet deinit.
     * @see javax.servlet.Servlet#destroy()
     */
    public void destroy() {
        super.destroy();
        loadbalancer = null;
        log.debug("Servlet destroyed");
    }

    protected void initLoadbalancerDelegate() {
        if (loadbalancer == null) {
            try {
                loadbalancer = (LoadbalancerServiceMBean) MBeanProxyExt.create(LoadbalancerServiceMBean.class,
                        loadbalancerName);
            } catch (MalformedObjectNameException ex) {
                log.error("Could not create LoadbalancerService-Proxy", ex);
            }

        }
    }
}