Question

I have an app on my iPhone called iSeismometer which reads the iPhone’s accelerometers and acts as a server which streams this data via UDP (I can set the IP address and port number). The question is how to read this data stream with Mathematica? Apparently, Dreeves has been looking into this 12 years ago, so I imagine something must have happened in the meantime.

Update
I got two great answers so far; one from WReach and one from Mark McClure. Both are using JLink to get at the data. This seems like a fine approach. However, I was reminded of some work I did on the WII balance board. Using a few free programs (GlovePIE and PPJoy) I got this bluetooth peripheral to appear as a joystick to Windows, and therefore also to Mathematica (via ControllerState). Of course, bluetooth and UDP are quite different, but could something along the same lines be made to work too?

Answer 1

JLink is definitely the way to go. I prefer to keep my Java code and my Mathematica code separate by compiling a Java programwhich I then call from Mathematica. I set up a Notebook and companion Java program that you can grab here:
http://facstaff.unca.edu/mcmcclur/UDPFiles.tar.gz

Here is the essential Mathematica code:

Needs["JLink`"];
InstallJava[];
AddToClassPath[NotebookDirectory[]];
udpReader = JavaNew["myClient"];
i = 0;
While[True && i++ < 100,
  Print[udpReader@udpReadOne[10552]]]

The updReader class is defined by the following Java code.

// A simple UDP client to read from iseismometer:
// http://www.iseismometer.com/
// You can run this from the command line via "java myClient"
// to check that your iseismometer setup is correct or you can
// call the the udpReadOne method from another program.

import java.io.*;
import java.net.*;
import java.util.*;

public class myClient {
    public static void main() throws IOException {
        DatagramSocket socket = new DatagramSocket(10552);
        byte[] buffer = new byte[500];
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
        while(true) {
            socket.receive(packet);
            String received = new String(packet.getData(), 0, packet.getLength());
            System.out.println(received);
        }
    }

    public static String udpReadOne(int port) throws IOException {
        DatagramSocket socket = new DatagramSocket(port);
        byte[] buffer = new byte[100];
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
        socket.receive(packet);
        String received = new String(packet.getData(), 0, packet.getLength());
        socket.close();
        return received;
    }
}

Note that you can use the main method of the myClient class to check that your setup is working without Mathematica, essentially taking one potential issue out of the loop.