one of the question the I have encountered is that do we need to send messages from client to the server through Multicast Scoket? or it needs to be only another way around?

the project requirement explicitly says that client unicast to the server , however the partial code for multicastclient sender has this line :

ms.send(dp, (byte) 1);

we know that the server is multi casting what client has sent . since the client is unicasting, does the server need to get the message by unicast (DatagramSocket)  or multicastSoket? asking this since the code sample has such a thing , and it seems that the server needs to join the multicast group as well .