1. Complete the partial code provided with this lab that implements a simple group communication application using Java's MulticastSocket class.

2. Change this program so that the members now send their ID and x messages (passed as arguments) and receive an unlimited number of messages. To identify the messages during the execution, you can use the following notation: MSG11 is the first message sent by member1, MSG32 is the second message transmitted by the member3. For example the first member will pass the following parameters: 1 3 228.5.6.7, specifying that the program the ID of the member which is 1, and that he will send 3 messages: MSG11, MSG12, and MSG13 to the group identified by the IP address 228.5.6.7.

1. In general, in group communication we need a coordinator to help coordinating all the members. For example, if the members need to order the received messages they will need the coordinator to tell them how to order these messages. Or, if the members need updates they can ask the coordinator. One thing that you will notice from the previous question is that a member will not receive the messages that were transmitted before he joins the group. In the next task, make sure that all new members receive the previously transmitted messages. This can be one of the roles of the coordinator.

You are asked to update the program of part 2 and making sure now that the coordinator keeps record of all transmitted messages and provides old messages to new members. The first member (ID1) to join the group will be considered as the coordinator. Its role is to act as a member, but also to send previously received messages to new members. The coordinator can deduce the IP address and port number of the new member that just joined the group and sends all previously received messages using UDP unicast interprocess communication.