C Losee

I'm working on a project where I'd like to receive UDP data from a motion capture suit.

I've seen a lot of discussion on the forums about sending raw bytes with UDP, but I haven't seen much in the way of receiving raw bytes with UDP.

Anybody have any C or Java code to do it on Windows (I've got XP professional and Max 5.0.7)? I'm pretty new to Max, and I've never worked with IP issues before, so any help would be appreciated.

receiving-bytes-with-udp

Well, after a bit of work, I've managed to piece something together, and I thought I'd post it in case anybody else is trying to do something similar.

If anybody has any improvements or suggestions let me know.

Also, I'm having some issues with Max being unresponsive while the UDP is receiving. I think it could be fixed with threading, but I'm not sure exactly how that would work. If anybody has suggestions, again, let me know.

Here's the code (note: this receives a packet every time there is a bang. If you wanted to continuously receive data, a loop works too):

    private static final String[] INLET_ASSIST = new String[]

    private static final String[] OUTLET_ASSIST = new String[]

        port = 7374; //default port

        declareInlets(new int[]{DataTypes.ALL});

        declareOutlets(new int[]{DataTypes.ALL});

        setInletAssist(INLET_ASSIST);

        setOutletAssist(OUTLET_ASSIST);

        declareAttribute("port"); //make port an attribute

            // Create a socket to listen on the port.

            DatagramSocket dsocket = new DatagramSocket(port);

            // Create a buffer to read datagrams into. If a packet is larger than 

            //this buffer, the excess will simply be discarded!

            byte[] buffer = new byte[2048];

            // Create a packet to receive data into the buffer

            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

            // Wait to receive a datagram

            dsocket.receive(packet);

            byte[] theData = packet.getData();

            // Reset the length of the packet before reusing it.

            packet.setLength(buffer.length);

    //Catchall for receiving a message that isn't a bang

    public void anything(String msg, Atom[] args)

        post("I received a " + msg + " message.");

            post("It has the following arguments:");

                post(args[i].toString());

Well, after a bit of work, I've managed to piece something together, and I thought I'd post it in case anybody else is trying to do something similar.
If anybody has any improvements or suggestions let me know.
Also, I'm having some issues with Max being unresponsive while the UDP is receiving. I think it could be fixed with threading, but I'm not sure exactly how that would work. If anybody has suggestions, again, let me know.

import com.cycling74.max.*;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

	private static final String[] INLET_ASSIST = new String[]
	{
		"inlet 1 help"
	};
	private static final String[] OUTLET_ASSIST = new String[]
	{
		"outlet 1 help"
	};

	public testUDP(Atom[] args)
	{
		port = 7374; //default port

		declareInlets(new int[]{DataTypes.ALL});
		declareOutlets(new int[]{DataTypes.ALL});

		setInletAssist(INLET_ASSIST);
		setOutletAssist(OUTLET_ASSIST);

		declareAttribute("port"); //make port an attribute

	public void bang()
	{
		try 
		{
			// Create a socket to listen on the port.
			DatagramSocket dsocket = new DatagramSocket(port);

			// Create a buffer to read datagrams into. If a packet is larger than 
			//this buffer, the excess will simply be discarded!
			byte[] buffer = new byte[2048];

			// Create a packet to receive data into the buffer
			DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

			// Wait to receive a datagram
			dsocket.receive(packet);

			// Reset the length of the packet before reusing it.
			packet.setLength(buffer.length);

			dsocket.close();
		}
		 catch (Exception e) 
		{
	      System.err.println(e);
		}

	//Catchall for receiving a message that isn't a bang
	public void anything(String msg, Atom[] args)
	{
		post("I received a " + msg + " message.");
		if (args.length > 0)
		{
			post("It has the following arguments:");
			for (int i=0;i
				post(args[i].toString());
		}
	}
}


Sorry for the negative message rather than a helpful one but you're in the wrong forum. There's a java dev forum.

BTW the unreponsiveness will be due to the

code in the bang() method, this blocks until the packet is received so yes you need to use multithreading.

BTW the unreponsiveness will be due to the 

code in the bang() method, this blocks until the packet is received so yes you need to use multithreading.


i saw this the other day, which might help. Didn't try it myself

http://www.esbasel.ch/Downloads/UdpSend+RecvRaw.zip

receiving bytes with UDP