function Ajax()
{
    this.params = new String();
    this.headers = null;
    this.callback = null;
    this.xmlHttp = this.getInstance();
}

Ajax.prototype.getInstance = function()
{
    return (window.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
}

Ajax.prototype.setRequestHeader = function(senderHeader)
{
    this.headers = senderHeader;
}

Ajax.prototype.addHeaders = function()
{
    for (i in this.headers)
    {
        this.xmlHttp.setRequestHeader(i, this.headers[i]);
    }
}

Ajax.prototype.addParam = function(name, value)
{
    this.params += name + '=' + encodeURI(value) + '&';
}

Ajax.prototype.addCallback = function(callback)
{
    this.callback = callback;
}

Ajax.prototype.parseUrlParams = function(method, url)
{
    if (method.toUpperCase() != 'POST')
    {
        url += '?' + this.params;
        this.params = null;
    }
    
    return url;
}

Ajax.prototype.parseResponseProperty = function()
{
    if (this.xmlHttp.getResponseHeader('Content-Type') == 'text/xml')
    {
        return 'XML';
    }
    
    return 'Text';
}

Ajax.prototype.getRequest = function(method, url, asinFlag)
{
    this.xmlHttp.open(method, this.parseUrlParams(method, url), asinFlag);
    this.addHeaders();
    
    var self = this;
    this.xmlHttp.onreadystatechange = function(){self.getData.call(self)};
    this.xmlHttp.send(this.params);
}

Ajax.prototype.getData = function()
{
    if (this.xmlHttp.readyState == 4 && this.xmlHttp.status == 200)
    {
        if (this.callback)
        {
            this.callback.call(this, this.xmlHttp['response' + this.parseResponseProperty()]);
        }
    }
}