This is readme about exam2

1.Change to the directory that contains the files.

2.Complier all the .java files
   Using command: javac *.java

3.Produce stub.
   Using command:rmic MessageCenterImpl

4.Run the reiregistry application
  Using command: rmiregistry

5.In a separate console window,run the server.
  Using command:java MessageCenterServer hostname.
  Note: hostname is the machine where the rmiregistry application was run.

6.In s separate console window ,run the client:
  Using command:java MessageCenterClient hostname.
  Note: hostname is the machine where the rmiregistry application was run.

7.You can execute 4 methods:
  (1) register: 
    You need to enter your name and password.
    note:the name and password should be unique.

  (2) showUsers:
    This method can show all the users who haved registered.

  (3) checkMessage:
    You should enter your name and password to check all your messages .

  (4)leaveMessage:
    You can leave messages to anyone who have registered by entering your name ,the receiver's name and the message.
  
8.You can enter exit to exit the progrom.