/*
url-loading object and a request queue built on top of it
*/

/* namespacing object */
var net=new Object();

net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;
net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;


/*--- content loader object for cross-browser requests ---*/
net.ContentLoader=function(url,onload,onerror,method,params, onerrorParams, contentType){
  this.req=null;
  this.onload=onload;
  this.onerror=(onerror) ? onerror : this.defaultError;
   this.onerrorParams=onerrorParams;
  this.loadXMLDoc(url,method,params,contentType);
}

net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
  if (!method){
    method="GET";
  }
  if (!contentType && method=="POST"){
    contentType='application/x-www-form-urlencoded';
  }
  try{
	  	if (window.XMLHttpRequest){
	    	this.req=new XMLHttpRequest();
	  	} else if (window.ActiveXObject){
	    	this.req=new ActiveXObject("Microsoft.XMLHTTP");
	  	}
		if (this.req){
	      var loader=this;
	      this.req.onreadystatechange=function(){
	        net.ContentLoader.onReadyState.call(loader);
	      }
	      this.req.open(method,url,true);
	      if (contentType){
	        this.req.setRequestHeader('Content-Type', contentType);
	      }
	      this.req.send(params);
	    }
  	}catch (err){
	      this.onerror.call(this, this.onerrorParams);
	}
}


net.ContentLoader.onReadyState=function(){
  var req=this.req;
  var ready=req.readyState;
  if (ready==net.READY_STATE_COMPLETE){
    var httpStatus=req.status;
    if (httpStatus==200 || httpStatus==0){
      this.onload.call(this);
    }else{
      this.onerror.call(this);
    }
  }
}

net.ContentLoader.prototype.defaultError=function(){
  alert("error fetching data!"
    +"\n\nreadyState:"+this.req.readyState
    +"\nstatus: "+this.req.status
    +"\nheaders: "+this.req.getAllResponseHeaders());
}