Multi-casting by UDP
For more information about this application please contact:

An Internet based application with graphical interface, which sends text messages to an multicast IP address, which shows who is connected to that address.

1. Messages are sent with 1 second interval. It sends as own-defined protocol called OTTP, It stands for Online Text Transfer Protocol:-) Format:

send(" From: " + name + " Host: " + host + " Comment: " + comment);
Our send command sends message with following attributes:
- name, name of sender
- host, user's host - comment, Comments from sender/user
This is important to send messages once in second(not many messages in a same second); when we use UDP. Please note that UDP doesn't have any "Traffic control". If we send messages;using UDP; several times during same second, there is a risk for conflicts, overloading and simply a system can crash.

(2) This application receives messages from multicast server and parses messages to following format:

name --- host --- comment

Only one line per user is displayed in client's GUI. If a received message is out of OTTP format then message "COULD NOT PARSE MESSAGE i displayed in TextArea.
Make a jar file and run following command:

java -jar OnLine.jar <name> <comment> After this our client connects to multicast-adress on port 2000. If connection was successful the client shows where it is connected. If connection fails clients terminates.

Download following jar file it contains all neccessary classes:
  • OnLine.jar

  • run the application as follow:
    java -jar OnLine.jar <name> <comments>