1   /**
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
   10    *
   11    * Unless required by applicable law or agreed to in writing, software
   12    * distributed under the License is distributed on an "AS IS" BASIS,
   13    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   14    * See the License for the specific language governing permissions and
   15    * limitations under the License.
   16    */
   17   package org.apache.activemq.transport.discovery.http;
   18   
   19   import java.io.IOException;
   20   import java.io.PrintWriter;
   21   import java.util.ArrayList;
   22   import java.util.Map;
   23   import java.util.concurrent.ConcurrentHashMap;
   24   
   25   import javax.servlet.ServletException;
   26   import javax.servlet.http.HttpServlet;
   27   import javax.servlet.http.HttpServletRequest;
   28   import javax.servlet.http.HttpServletResponse;
   29   
   30   import org.apache.commons.logging.Log;
   31   import org.apache.commons.logging.LogFactory;
   32   
   33   public class DiscoveryRegistryServlet extends HttpServlet {
   34       
   35       private static final Log LOG = LogFactory.getLog(HTTPDiscoveryAgent.class);
   36       long maxKeepAge = 1000*60*60; // 1 hour.
   37       ConcurrentHashMap<String, ConcurrentHashMap<String, Long>> serviceGroups = new ConcurrentHashMap<String, ConcurrentHashMap<String, Long>>();
   38       
   39       @Override
   40       protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   41           String group = req.getPathInfo();
   42           String service = req.getHeader("service");
   43           LOG.debug("Registering: group="+group+", service="+service);
   44           
   45           ConcurrentHashMap<String, Long> services = getServiceGroup(group);
   46           services.put(service, System.currentTimeMillis());
   47       }
   48   
   49       private ConcurrentHashMap<String, Long> getServiceGroup(String group) {
   50           ConcurrentHashMap<String, Long> rc = serviceGroups.get(group);
   51           if( rc == null ) {
   52               rc = new ConcurrentHashMap<String, Long>();
   53               serviceGroups.put(group, rc);
   54           }
   55           return rc;
   56       }
   57   
   58       @Override
   59       protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   60           try {
   61               long freshness = 1000*30;
   62               String p = req.getParameter("freshness");
   63               if( p!=null ) {
   64                   freshness = Long.parseLong(p);
   65               }
   66               
   67               String group = req.getPathInfo();
   68               LOG.debug("group="+group);
   69               ConcurrentHashMap<String, Long> services = getServiceGroup(group);
   70               PrintWriter writer = resp.getWriter();
   71               
   72               long now = System.currentTimeMillis();
   73               long dropTime = now-maxKeepAge;             
   74               long minimumTime = now-freshness;
   75               
   76               ArrayList<String> dropList = new ArrayList<String>();
   77               for (Map.Entry<String, Long> entry : services.entrySet()) {
   78                   if( entry.getValue() > minimumTime ) {
   79                       writer.println(entry.getKey());
   80                   } else if( entry.getValue() < dropTime ) {
   81                       dropList.add(entry.getKey());
   82                   }
   83               }
   84               
   85               // We might as well get rid of the really old entries.
   86               for (String service : dropList) {
   87                   services.remove(service);
   88               }
   89               
   90               
   91           } catch (Exception e) {
   92               resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Error occured: "+e);
   93           }
   94       }
   95       
   96       @Override
   97       protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   98           String group = req.getPathInfo();
   99           String service = req.getHeader("service");
  100           LOG.debug("Unregistering: group="+group+", service="+service);
  101           
  102           ConcurrentHashMap<String, Long> services = getServiceGroup(group);
  103           services.remove(service);
  104       }
  105           
  106   }