ActiveMQ example source code file (DiscoveryRegistryServlet.java)

This example ActiveMQ source code file (DiscoveryRegistryServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

arraylist, concurrenthashmap, concurrenthashmap, http, httpservletresponse, io, ioexception, logger, long, long, override, printwriter, request, response, servlet, servletexception, servletexception, string, string, util

The ActiveMQ DiscoveryRegistryServlet.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.transport.discovery.http;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DiscoveryRegistryServlet extends HttpServlet {
    
    private static final Logger LOG = LoggerFactory.getLogger(HTTPDiscoveryAgent.class);
    long maxKeepAge = 1000*60*60; // 1 hour.
    ConcurrentHashMap<String, ConcurrentHashMap serviceGroups = new ConcurrentHashMap>();
    
    @Override
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String group = req.getPathInfo();
        String service = req.getHeader("service");
        LOG.debug("Registering: group="+group+", service="+service);
        
        ConcurrentHashMap<String, Long> services = getServiceGroup(group);
        services.put(service, System.currentTimeMillis());
    }

    private ConcurrentHashMap<String, Long> getServiceGroup(String group) {
        ConcurrentHashMap<String, Long> rc = serviceGroups.get(group);
        if( rc == null ) {
            rc = new ConcurrentHashMap<String, Long>();
            serviceGroups.put(group, rc);
        }
        return rc;
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            long freshness = 1000*30;
            String p = req.getParameter("freshness");
            if( p!=null ) {
                freshness = Long.parseLong(p);
            }
            
            String group = req.getPathInfo();
            LOG.debug("group="+group);
            ConcurrentHashMap<String, Long> services = getServiceGroup(group);
            PrintWriter writer = resp.getWriter();
            
            long now = System.currentTimeMillis();
            long dropTime = now-maxKeepAge;             
            long minimumTime = now-freshness;
            
            ArrayList<String> dropList = new ArrayList();
            for (Map.Entry<String, Long> entry : services.entrySet()) {
                if( entry.getValue() > minimumTime ) {
                    writer.println(entry.getKey());
                } else if( entry.getValue() < dropTime ) {
                    dropList.add(entry.getKey());
                }
            }
            
            // We might as well get rid of the really old entries.
            for (String service : dropList) {
                services.remove(service);
            }
            
            
        } catch (Exception e) {
            resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Error occured: "+e);
        }
    }
    
    @Override
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String group = req.getPathInfo();
        String service = req.getHeader("service");
        LOG.debug("Unregistering: group="+group+", service="+service);
        
        ConcurrentHashMap<String, Long> services = getServiceGroup(group);
        services.remove(service);
    }
        
}