function Ajax() {
	this.req = null;
	this.url = null;
	this.method = 'GET';
	this.async = true;
	this.status = null;
	this.statusText = '';
	this.postData = null;
	this.readyState = null;
	this.responseText = null;
	this.responseXML = null;
	this.handleResp = null;
	this.responseFormat = 'text'; // 'text', 'xml', or 'object'
	this.mimeType = null;

	this.init = function() {
		if (!this.req) {
			try {
				// Try to create object for Firefox, Safari, IE7, etc.
				this.req = new XMLHttpRequest();
			}
			catch (e) {
				try {
					// Try to create object for later versions of IE.
					this.req = new ActiveXObject('MSXML2.XMLHTTP');
				}
				catch (e) {
					try {
						// Try to create object for early versions of IE.
						this.req = new ActiveXObject('Microsoft.XMLHTTP');
					}
					catch (e) {
						// Could not create an XMLHttpRequest object.
						return false;
					}
				}
			}
		}
		return this.req;
	};

	/*
	// Don't work in IE6 or Opera.
	this.setMimeType = function(mimeType) {
		this.mimeType = mimeType;
	};
	*/

	this.handleErr = function() {
		var errorWin;
		try {
			errorWin = window.open('', 'errorWin');
			errorWin.document.body.innerHTML = this.responseText;
		}
		catch (e) {
			alert('An error occurred, but the error message cannot be '
			+ 'displayed. This is probably because of your browser\'s '
			+ 'pop-up blocker.\n'
			+ 'Please allow pop-ups from this web site if you want to '
			+ 'see the full error messages.\n'
			+ '\n'
			+ 'Status Code: ' + this.req.status + '\n'
			+ 'Status Description: ' + this.req.statusText);
		}
	};

	this.setHandlerErr = function(funcRef) {
		this.handleErr = funcRef;
	}

	// A mesma função deverá irá cuidar da resposta ou do erro.
	// Esta função não é necessária já que em "doGet" já passamos a função para resposta.
	this.setHandlerBoth = function(funcRef) {
		this.handleResp = funcRef;
		this.handleErr = funcRef;
	};

	this.abort = function() {
		if (this.req) {
			this.req.onreadystatechange = function() { };
			this.req.abort();
			this.req = null;
		}
	};

	this.doReq = function() {
		if (!this.init()) {
			alert('Could not create XMLHttpRequest object.');
			return;
		}
		this.req.open(this.method, this.url, this.async);

		/*
		// Don't work in IE6 or Opera.
		if (this.mimeType) {
			try {
				req.overrideMimeType(this.mimeType);
			}
			catch (e) {
				// couldn't override MIME type -- IE6 or Opera?
			}
		}
		*/

		var self = this; // Fix loss-of-scope in inner function
		this.req.onreadystatechange = function() {
			var resp = null;
			if (self.req.readyState == 4) {
				switch (self.responseFormat) {
					case 'text':
						resp = self.req.responseText;
						break;
					case 'xml':
						resp = self.req.responseXML;
						break;
					case 'object':
						resp = req; // task: self.req?
						break;
				}
				if (self.req.status >= 200 && self.req.status <= 299) {
					self.handleResp(resp);
				}	else {
					self.handleErr(resp);
				}
			}
		};
		this.req.send(this.postData);
	};

	this.doGet = function(url, hand, format) {
		this.url = url;
		this.handleResp = hand;
		this.responseFormat = format || 'text';
		this.doReq();
	};
}