this repository is communication using protocol udp with the server using nodejs and the client using java, before you use this repository i'm reommended to read this article UDP introduction, because any some different in TCP and UDP.

• install nodejs
  

• install java SDK,JRE or
  

• install IDE(recomended Netbeans because the repository using netbeans)
  

• run the server that been use nodejs
  

• for the server code
  

    var dgram = require("dgram");
    var server = dgram.createSocket("udp4");
    server.on("message", function (msg, rinfo) {
    var data = JSON.parse(msg);
    console.log("server got: " + data.balance + " from " + rinfo.address + ":" + rinfo.port);
    
    var data = {
        "name" : "test",
        "args" : {
            "data":[{
                "a":1
            }]
            }
        };
    //send data to client
    var message = new Buffer(JSON.stringify(data));//JSON.stringify(data)
    server.send(message, 0, message.length, rinfo.port, rinfo.address, function(err, bytes) {
        console.log("error mamen = " + err );
        console.log("data bytes = " + bytes);
    //server.close();
    });
    });

    server.on("listening", function () {
        var address = server.address();
        console.log("server listening " +
        address.address + ":" + address.port);
    });

    server.bind(41234);

save to app.js run with sudo node app.js

• run the UDPImplementation.java to test application
  

        public static void main(String[] args) throws UnknownHostException, SocketException, IOException {
        InetAddress IPAddress =  InetAddress.getByName("localhost");
        byte[] sendData = new byte[1024];

        JSONObject obj = new JSONObject();
        obj.put("name", "viyancs");
        obj.put("num", new Integer(100));
        obj.put("balance", new Double(1000.21));
        obj.put("is_vip", new Boolean(true));
        obj.put("nickname",null);

        sendData = obj.toJSONString().getBytes();
        SocketUDP client = new SocketUDP(IPAddress,41234,callback);
        client.connect();
        client.send(sendData);
        client.initReceive();
        client.close();
        client.disconnect();
    }
    
    final static public UDPCallback callback = new UDPCallback() {

        @Override
        public void onConnect() {
            System.out.println("server is connected");
        }
        
        @Override
        public void onMessage(String event, JSONArray json) {
            System.out.println("the event is " + event + "\n");
            System.out.println("the data is " + json.toJSONString() + "\n");
        }

        @Override
        public void onMessage(String data) {
            System.out.println("data from server : " + data);
        }
        
        @Override
        public void onMessage(JSONObject msg) {
            System.out.println("data from server = " + msg.toJSONString());           
        }
        @Override
        public void onMessage(String event, JSONObject json) {
            System.out.println("data from server = " + json.toJSONString());  
        }
    

        @Override
        public void onClose() {
            System.out.println("client is close the request");
        }

        @Override
        public void onError(ParseException ex) {
            System.out.println("something wrong : " + ex.getMessage());
        }

        @Override
        public void onDisconnect() {
            System.out.println("client is disconnect");
        }
    };

• send data using string format
• send data using JSONFormat (JSONObject,JSONArray) and dynamical JSON.
• receive data using string format
• receive data using json format

• missing detected server is active or not

if you want to use this repository please don't remove comment in each code, fork and follow this repository if any question send email to [email protected] , i wanna to update this code to be better.