import java.rmi.*;
/**
 * Remote Interface for the chat server for ex6
 */
public interface ChatInterface extends Remote {
  /**
   * Method to find out what message to poll
   * @return the next (expected) message-id
   * @exception RemoteException if the remote invocation fails.
   */
  public int getMessId() throws RemoteException;
  

  /**
   * Method to join a chat
   * @param username your username string for chat
   * @return the next (expected) message-id, -1 if not success
   * @exception RemoteException if the remote invocation fails.
   */
  public int join(String username) throws RemoteException;

  
  /**
   * Poll for a new message
   * @param messageid the message id requested
   * @return A string containing the username and the message, NULL
   * if no such message is available. Username of the message sender
   * is the first word (space separated) of the message.
   * @exception RemoteException if the remote invocation fails.
   */
  public String pollMessage(int messageid) throws RemoteException;


  /**
   * Post a new message
   * @param username sender's username
   * @param message the message
   * @return the message id
   * @exception RemoteException if the remote invocation fails.
   */
  public int postMessage(String username, String message) throws RemoteException;

  
  /**
   * Disconnect a chat (actually, we could have done without this)
   * @param username your username
   * @exception RemoteException if the remote invocation fails.
   */
  public void disconnect(String username) throws RemoteException;

} // interface ChatInterface