public void sendRequest(String host, String uri) {
		if (this.host == null)
			this.host = host;
		HttpRequest request = new DefaultHttpRequest(HttpVersion.HTTP_1_1,
				HttpMethod.GET, uri);
		logger.info("send request to " + host + " : " + uri);
		request.setHeader(HttpHeaders.Names.HOST, host);
		if (downloadFile != null)
			request.setHeader(HttpHeaders.Names.CACHE_CONTROL,
					Long.toString(downloadFile.lastModified()));
		channel.write(request);
	}