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MudServer.javaAPI DocExample6100Mon Sep 22 13:30:32 BST 1997None

MudServer

public class MudServer extends UnicastRemoteObject implements RemoteMudServer, Serializable
This class implements the RemoteMudServer interface. It also defines a main() method so you can run it as a standalone program that will set up and initialize a MUD server. Note that a MudServer maintains an entrance point to a MUD, but it is not the MUD itself. Most of the interesting MUD functionality is defined by the RemoteMudPlace interface and implemented by the RemotePlace class. In addition to being a remote object, this class is also Serializable, so that the state of the MUD can be saved to a file and later restored. Note that the main() method defines two ways of starting a MUD: one is to start it from scratch with a single initial place, and another is to restore an existing MUD from a file.

Fields Summary
MudPlace
entrance
String
password
String
mudname
Hashtable
places
static final long
serialVersionUID
This constant is a version number for serialization
Constructors Summary
public MudServer(String mudname, String password, String placename, String description)
Start a MUD from scratch, with the given name and password. Create an initial MudPlace object as the entrance, giving it the specified name and description.

    this.mudname = mudname;
    this.password = password;
    this.places = new Hashtable();
    // Create the entrance place
    try { this.entrance = new MudPlace(this, placename, description); } 
    catch (PlaceAlreadyExists e) {} // Should never happen
  
public MudServer()
For serialization only. Never call this constructor.

Methods Summary
public voiddump(java.lang.String password, java.lang.String f)
This remote method serializes and compresses the state of the MUD to a named file, if the specified password matches the one specified when the MUD was initially created. Note that the state of a MUD consists of all places in the MUD, with all things and exits in those places. The people in the MUD are not part of the state that is saved.

    if ((this.password != null) && !this.password.equals(password)) 
      throw new BadPassword();
    ObjectOutputStream out = 
      new ObjectOutputStream(new GZIPOutputStream(new FileOutputStream(f)));
    out.writeObject(this);
    out.close();
  
public RemoteMudPlacegetEntrance()
This remote method returns the entrance place of the MUD

 
    return entrance; 
  
public java.lang.StringgetMudName()
This remote method returns the name of the MUD

 return mudname; 
public RemoteMudPlacegetNamedPlace(java.lang.String name)
This remote method returns a RemoteMudPlace object for the named place. In this sense, a MudServer acts as like an RMI Registry object, returning remote objects looked up by name. It is simpler to do it this way than to use an actual Registry object. If the named place does not exist, it throws a NoSuchPlace exception

    RemoteMudPlace p = (RemoteMudPlace) places.get(name);
    if (p == null) throw new NoSuchPlace();
    return p;
  
public static voidmain(java.lang.String[] args)
This main() method defines the standalone program that starts up a MUD server. If invoked with a single argument, it treats that argument as the name of a file containing the serialized and compressed state of an existing MUD, and recreates it. Otherwise, it expects four command-line arguments: the name of the MUD, the password, the name of the entrance place for the MUD, and a description of that entrance place. Besides creating the MudServer object, this program sets an appropriate security manager, and uses the default rmiregistry to register the the MudServer under its given name.

    try {
      MudServer server;
      if (args.length == 1) {
        // Read the MUD state in from a file
        FileInputStream f = new FileInputStream(args[0]);
        ObjectInputStream in = new ObjectInputStream(new GZIPInputStream(f));
        server = (MudServer) in.readObject();
      }
      // Otherwise, create an initial MUD from scratch
      else server = new MudServer(args[0], args[1], args[2], args[3]);

      System.setSecurityManager(new RMISecurityManager());
      Naming.rebind(Mud.mudPrefix + server.mudname, server);
    }
    // Display an error message if anything goes wrong.
    catch (Exception e) {
      System.out.println(e);
      System.out.println("Usage: java MudServer <savefile>\n" +
                         "   or: java MudServer <mudname> <password> " + 
                         "<placename> <description>");
      System.exit(1);
    }
  
public voidsetPlaceName(RemoteMudPlace place, java.lang.String name)
Define a new placename to place mapping in our hashtable. This is not a remote method. The MudPlace() constructor calls it to register the new place it is creating.

    if (places.containsKey(name)) throw new PlaceAlreadyExists();
    places.put(name, place);