Comet 先记下来

 

Comet 是ajax新的应用，通俗的讲就是能push数据到客户端。在web中，要实现push到客户端，一般有两种方法：

  1 Flash/Java Applet  +  Javascript 

  2 Pure Javascript

纯javascript实现网上有一个 prototype implements 。本文用mootools改写的实现

 
Comet = new Class(...{
    initialize : function(url,param,httpMethod,timeOut)...{
        this.url     = url;
        this.param   = param || ...{};
        this.type    = httpMethod || 'get' ;
        this.timeout = timeOut || 2*1000 ;
    }
  }).extend(new Events);

  Comet.implement(...{
        ajax     : null,
        stamp    : '0',
      connect  : function()...{
          this.ajax = new XHR(...{
              'method'    : this.type,
              'onSuccess' : this.success.bind(this),
              'onFailure' : this.failure.bind(this)
            }
          );
          this.param.stamp = this.stamp;
          this.ajax.send(this.url,Object.toQueryString(this.param));
      },
      success  : function(response)...{
          var r = this.evalJSON(response);
          if(typeof r === 'string') ...{
              this.fireEvent('timeout',r);
          } else ...{
              this.stamp = r['stamp'] || this.stamp;
              this.fireEvent('ready',r);
          }
          this.connect.delay(this.timeout,this);
      },
      failure  : function(response)...{
          (function()...{this.connect();}).delay(this.timeout,this);
      },
      evalJSON: function(response) ...{
        try ...{ return Json.evaluate(response);} catch (e) ...{ return response;}
    }
   }
  );

 

用法很简单，

 
cm = new Comet(url);
cm.connect();
//so you can add your event handler when accept any data from server
cm.addEvent('ready',function(r)...{ alert(r) });

 
 还没有实现用stream形式的xmlhttpRequest。下个版本更新。

 实例代码点击下载