function sack(file) {
    this.xmlhttp = null;
    this.resetData = function() {
	this.method = "POST";
	this.queryStringSeparator = "?";
	this.argumentSeparator = "&";
	this.URLString = "";
	this.encodeURIString = true;
	this.execute = false;
	this.element = null;
	this.elementObj = null;
	this.requestFile = file;
	this.vars = new Object();
	this.responseStatus = new Array(2);
    };
    this.resetFunctions = function() {
	this.onLoading = function() { };
	this.onLoaded = function() { };
	this.onInteractive = function() { };
	this.onCompletion = function() { };
	this.onError = function() { };
	this.onFail = function() { };
    };
    this.reset = function() {
	this.resetFunctions();
	this.resetData();
    };
    this.createAJAX = function() {
	try {
	    this.xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
	    } catch (e1) {
		try {this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e2) {
		    this.xmlhttp = null;
		}
	    }
	    if (! this.xmlhttp) {
		if (typeof XMLHttpRequest != "undefined") {
		    this.xmlhttp = new XMLHttpRequest();
		} else {
		    this.failed = true;
		}
	    }
    };
    this.setVar = function(name, value){
	this.vars[name] = Array(value, false);
    };
    this.encVar = function(name, value, returnvars) {
	if (true == returnvars) {
	    return Array(encodeURIComponent(name), encodeURIComponent(value));
	} else {
	    this.vars[encodeURIComponent(name)] = Array(encodeURIComponent(value), true);
	}
    }
    this.processURLString = function(string, encode) {
	encoded = encodeURIComponent(this.argumentSeparator);
	regexp = new RegExp(this.argumentSeparator + "|" + encoded);
	varArray = string.split(regexp);
	for (i = 0; i < varArray.length; i++){
	    urlVars = varArray[i].split("=");
	    if (true == encode){
		this.encVar(urlVars[0], urlVars[1]);
	    } else {
		this.setVar(urlVars[0], urlVars[1]);
	    }
	}
    }
    this.createURLString = function(urlstring) {
	if (this.encodeURIString && this.URLString.length) {
	    this.processURLString(this.URLString, true);
	}
	if (urlstring) {
	    if (this.URLString.length) {
		this.URLString += this.argumentSeparator + urlstring;
	    } else {
		this.URLString = urlstring;
	    }
	}
	// prevents caching of URLString
	this.setVar("rndval", new Date().getTime());
	urlstringtemp = new Array();
	for (key in this.vars) {
	    if (false == this.vars[key][1] && true == this.encodeURIString) {
		encoded = this.encVar(key, this.vars[key][0], true);
		delete this.vars[key];
		this.vars[encoded[0]] = Array(encoded[1], true);
		key = encoded[0];
	    }
	    urlstringtemp[urlstringtemp.length] = key + "=" + this.vars[key][0];
	}
	if (urlstring){
	    this.URLString += this.argumentSeparator + urlstringtemp.join(this.argumentSeparator);
	} else {
	    this.URLString += urlstringtemp.join(this.argumentSeparator);
	}
    }
    this.runResponse = function() {
	eval(this.response);
    }
    this.runAJAX = function(urlstring) {
	if (this.failed) {
	    this.onFail();
	} else {
	    this.createURLString(urlstring);
	    if (this.element) {
		this.elementObj = document.getElementById(this.element);
	    }
	    if (this.xmlhttp) {
		var self = this;
		if (this.method == "GET") {
		    totalurlstring = this.requestFile + this.queryStringSeparator + this.URLString;
		this.xmlhttp.open(this.method, totalurlstring, true);
		} else {
		    this.xmlhttp.open(this.method, this.requestFile, true);
		    try {
			this.xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded")
		    } catch (e) { }
		}
		this.xmlhttp.onreadystatechange = function() {
		    switch (self.xmlhttp.readyState) {
			case 1:
			    self.onLoading();
			    break;
			case 2:
			    self.onLoaded();
			    break;
			case 3:
			    self.onInteractive();
			    break;
			case 4:
			    self.response = self.xmlhttp.responseText;
			    self.responseXML = self.xmlhttp.responseXML;
			    self.responseStatus[0] = self.xmlhttp.status;
			    self.responseStatus[1] = self.xmlhttp.statusText;
			    if (self.execute) {
				self.runResponse();
			    }
			    if (self.elementObj) {
				elemNodeName = self.elementObj.nodeName;
				elemNodeName.toLowerCase();
				if (elemNodeName == "input" || elemNodeName == "select" || elemNodeName == "option" || elemNodeName == "textarea") {
				    self.elementObj.value = self.response;
				} else {
				    self.elementObj.innerHTML = self.response;
				}
			    }
			    if (self.responseStatus[0] == "200") {
				self.onCompletion();
			    } else {
				self.onError();
			    }
			    self.URLString = "";
			    break;
		    }
		};
		this.xmlhttp.send(this.URLString);
	    }
	}
    };
    this.reset();
    this.createAJAX();
}