/*
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 ---*/
/*
url     - AjaxSessionUpdate.aspx
onload  - finishrequest
onerror - null
method  - POST (For passing data to the server longer than 512 bytes you will need to use POST. 
                The amount of data returned by the script is not an issue here - only what's sent.)
params  - ts=WedJul16135830EDT2008

// url - URL a script on the server which will process search
// onload - callback-function, after loading
// onerror - callback-function, in case of a mistake
// method - a method of sending of search (POST, GET)
// params - parameters of search 
// contentType - type of a content of search (text/html)
*/
net.ContentLoader=function(url,onload,onerror,method,params,contentType){
  this.req=null;
  this.onload=onload;
  this.onerror=(onerror) ? onerror : this.defaultError;
  this.loadXMLDoc(url,method,params,contentType);
}

  /* Connect an HTML presentation directly to XML data for interim updates 
     without reloading the page.   */
net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
  if (!method){
    method="GET";
  }
  if (!contentType && method=="POST"){
    contentType='application/x-www-form-urlencoded';
  }

  if (window.XMLHttpRequest){
    this.req=new XMLHttpRequest();
  } else if (window.ActiveXObject){
    this.req=new ActiveXObject("Microsoft.XMLHTTP");
  }
  if (this.req){
    try{
      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);
    }
  }
}


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());
}