Server:

1. Use multi threads to handle message receiving, message operations and user command input;
2. Support three kinds of command including clear out message, send message or display message;
3. Serve four types of client's request, including clear and restart, clear and ignore, combine and sort by SeqNum and send to all clients;
4. Message length regulation, if length is larger than a certain number, then send to all the clients;
5. Linux environment; Windos also works;

Client:

1. Use multi threads to handle message receiving, message operations and user command input;
2. Support four types of requests, mentioned in the Server part;