public void sendUnicast(Serializable content, Address to) throws IOException {
		ObjectOutputStream out = unicastStreams.get(to);
		// create output stream if necessary
		if (out == null) {
			// create socket
			Socket tcpClientSocket = new Socket(to.getIpAddress(), to.getTcpPort());
			// build a stream to write objects on that socket
			out = new ObjectOutputStream(tcpClientSocket.getOutputStream());
			unicastStreams.put(to, out);
			// send this application's address
			out.writeObject(getAddress());
			out.flush();
			if (verbose) {
				System.out.println("Net: sender connected to "
						+ tcpClientSocket.getInetAddress().getHostAddress() + ":"
						+ tcpClientSocket.getPort());
			}
		}
		out.writeObject(content);
		out.flush();
		if (verbose) {
			System.out.println("Net: sender sent " + content + " to " + to);
		}
	}