ActiveMQ(AMQ)单浏览器AJAX多页面客户端的支持(clientId)

    最近同事在使用AMQ进行消息通信时遇到了问题:

    在IE8中多个页面上访问AMQ的一个主题订阅的时候,多个页面中获得的消息其实是来自于同一个主题队列,导致页面状态逻辑错误.

    查找AMQ的官方文档后得知,在5.4.2之后的版本中,AMQ的AJAX客户端可以通过指定唯一的clientId,让多个页面在一个浏览器中能够访问相同订阅的不同队列,避免了之前版本中只判断JSESSIONID导致的客户端无法区分的问题.官方文档在这里:

    http://activemq.apache.org/ajax.html     但这里面实现的amq.js由于改动过大,无法与之前的接口兼容,所以并没有合并到官方主干源码中,只是以demo的形式额外存放.但实现上述功能的后端代码从5.4.2之后都被主干源码合并.

    所以,单纯使用最新版的AMQ,是无法得到这个AJAX多客户端的功能的,需要自己额外进行调整.

    今天上午解决了这个问题,稍稍修改了一下_amq.js文件,保证了与原接口的一致性,又增加了initClientId方法,可以方便的使用AMQ的AJAX多客户端功能了.  

    使用时,可以将这个_amq.js替换原activemq_web-x.x.x.jar中的文件,同时在调用页面中,进行最初uri赋值的时候,顺手调用一下amq.initClientId();就可以开启这个功能了.

    刚刚进行代码测试,初步通过,功能的正确性得到了初步验证.

    如果有同学遇到了相同的问题,希望能够帮忙进行测试调整.

    文章系本人原创，转载请注明出处和作者 ,本文原址在http://h-rain.iteye.com/blog/1387640

 

/**
 * 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.
 */

// AMQ Ajax handler
// This class provides the main API for using the Ajax features of AMQ. It
// allows JMS messages to be sent and received from javascript when used
// with the org.apache.activemq.web.MessageListenerServlet
//
var amq =
{
  // The URI of the MessageListenerServlet
  uri: '/amq',

  // Polling. Set to true (default) if waiting poll for messages is needed
  poll: true,
  
  // Poll delay. if set to positive integer, this is the time to wait in ms before
  // sending the next poll after the last completes.
  _pollDelay: 0,
  _clientIdStr:'',

  _first: true,
  _pollEvent: function(first) {},
  _handlers: new Array(),

  _messages:0,
  _messageQueue: '',
  _queueMessages: 0,
	
	//init the clientId,default auto make as Date string
	initClientId:function(newId)
	{
		if (newId)
			amq._clientIdStr="clientId="+newId;
		else
			amq._clientIdStr="clientId="+(new Date()).getTime().toString();
	},
	//using clientId,whit separtor
	_makeClientIdStr:function(spChar)
	{
		var SC=spChar||'';
		if (amq._clientIdStr=='')
			return '';
		return SC+amq._clientIdStr;
	},
  _messageHandler: function(request)
  {
    try
    {
      if (request.status == 200)
      {
        var response = request.responseXML.getElementsByTagName("ajax-response");
        if (response != null && response.length == 1)
        {
          for ( var i = 0 ; i < response[0].childNodes.length ; i++ )
          {
            var responseElement = response[0].childNodes[i];

            // only process nodes of type element.....
            if ( responseElement.nodeType != 1 )
              continue;

            var id   = responseElement.getAttribute('id');


            var handler = amq._handlers[id];
            if (handler!=null)
            {
              for (var j = 0; j < responseElement.childNodes.length; j++)
              {
                handler(responseElement.childNodes[j]);
	      }
            }
          }
        }
      }
    }
    catch(e)
    {
      alert(e);
    }
  },

  startBatch: function()
  {
    amq._queueMessages++;
  },

  endBatch: function()
  {
    amq._queueMessages--;
    if (amq._queueMessages==0 && amq._messages>0)
    {
      var body = amq._messageQueue;
      amq._messageQueue='';
      amq._messages=0;
      amq._queueMessages++;
      new Ajax.Request(amq.uri, { method: 'post', postBody: body+amq._makeClientIdStr('&'), onSuccess: amq.endBatch});
    }
  },

  _pollHandler: function(request)
  {
    amq.startBatch();
    try
    {
      amq._messageHandler(request);
      amq._pollEvent(amq._first);
      amq._first=false;
    }
    catch(e)
    {
        alert(e);
    }
    amq.endBatch();

    if (amq._pollDelay>0)
      setTimeout('amq._sendPoll()',amq._pollDelay);
    else
      amq._sendPoll();
  },
  
  _sendPoll: function(request)
  {
    new Ajax.Request(amq.uri, { method: 'get', parameters: amq._makeClientIdStr(),onSuccess: amq._pollHandler });
  },

  // Add a function that gets called on every poll response, after all received
  // messages have been handled.  The poll handler is past a boolean that indicates
  // if this is the first poll for the page.
  addPollHandler : function(func)
  {
    var old = amq._pollEvent;
    amq._pollEvent = function(first)
    {
      old(first);
      func(first);
    }
  },

  // Send a JMS message to a destination (eg topic://MY.TOPIC).  Message should be xml or encoded
  // xml content.
  sendMessage : function(destination,message)
  {
    amq._sendMessage(destination,message,'send');
  },

  // Listen on a channel or topic.   handler must be a function taking a message arguement
  addListener : function(id,destination,handler)
  {
    amq._handlers[id]=handler;
    amq._sendMessage(destination,id,'listen');
  },

  // remove Listener from channel or topic.
  removeListener : function(id,destination)
  {
    amq._handlers[id]=null;
    amq._sendMessage(destination,id,'unlisten');
  },

  _sendMessage : function(destination,message,type)
  {
    if (amq._queueMessages>0)
    {
      if (amq._messages==0)
      {
        amq._messageQueue='destination='+destination+'&message='+message+'&type='+type;
      }
      else
      {
        amq._messageQueue+='&d'+amq._messages+'='+destination+'&m'+amq._messages+'='+message+'&t'+amq._messages+'='+type;
      }
      amq._messages++;
    }
    else
    {
      amq.startBatch();
      new Ajax.Request(amq.uri, { method: 'post', postBody: 'destination='+destination+'&message='+message+'&type='+type+amq._makeClientIdStr('&'), onSuccess: amq.endBatch});
    }
  },
  
  _startPolling : function()
  {
   if (amq.poll)
      new Ajax.Request(amq.uri, { method: 'get', parameters: 'timeout=10'+amq._makeClientIdStr('&'), onSuccess: amq._pollHandler });
  }
};

Behaviour.addLoadEvent(amq._startPolling);

function getKeyCode(ev)
{
    var keyc;
    if (window.event)
        keyc=window.event.keyCode;
    else
        keyc=ev.keyCode;
    return keyc;
}

评论

1 楼 clamking 2014-03-28  

能给个前端调用页面的代码么？我不知道什么时候调用amq.initClientId();这个方法，amq里面没有这个方法，调用出错