t3.remotehrd.server
Class RemoteHRDServer

java.lang.Object
  t3.remotehrd.server.RemoteHRDServer

public class RemoteHRDServer
extends java.lang.Object

This class represents a RemoteHRD server. It has a HRD StateManager, and changes to the state are broadcast to any connected RemoteHRDClients.

You can use its StateManager as usual but with some restrictions: you must synchronize on it before you use it, or its Tiles, Cursors or Links; and you must call endOfBurst to ensure that changes get sent on to the clients.

We have one listener thread that listens for new connections. It does:

• while true
  • block waiting for new connection
  • call callback
  • create new client object and add to clients set
  • start client's receiver thread

We have one thread per client that receives and processes messages from that client. * It does:

• lock statemanager to prevent anyone updating tiles or cursors or sending messages to all clients
• send entire state to client
• add client to clientslinkedin set
• unlock
• while true
  • block waiting for new message from client
  • process that message
• and if the client leaves or has an error:
  • notify the clientsmanager, which removes the client from the clients set and the linkedinclients set
  • close the socket
  • call the callback

Processing is therefore multithreaded and uses locks on StateManager. You need to be careful with this. If you use the StateManager, or one of its Tiles, Links or Cursors then you will need to synchronize on StateManager first.

To send a message to all clients you call the manager's addToSendQueue method. If you perform operations on the StateManager or one if its Tiles, Links or Cursors then a message will automatically be generated and the addToSendQueue method invoked.

When you call addToSendQueue, the message is not sent immediately; instead it is added to a queue and might not be sent until you call endOfBurst. Messages within a burst might be amalgamated to save processing time and network bandwidth.

There are two modes for sending:

• In alwaysServerPush mode we send messages to the client as soon as you call hindEndOfBurst.
• In the other mode, we buffer messages until the client sends a ready message. At that point we send whatever is waiting in the queues, regardless of whether you have called endOfBurst. Any calls to endOfBurst will be ignored - we wait for the ready message. If the client we receieve a ready but there is nothing waiting in the queues then we send messages when you next call endOfBurst.

Author:

pjt40

Field Summary

java.util.Map<java.lang.Integer,Client>	allClientsClientIdToClientsImmutable
RemoteHRDServerCallBacks	callBacks
StateManager	stateManager See notes above.

Constructor Summary

RemoteHRDServer(java.net.ServerSocket serverSocket, java.net.ServerSocket inputSourceServerSocket, RemoteHRDServerCallBacks callBacks, boolean alwaysServerPush)
Creates a RemoteHRDServer and starts the listening thread.

Method Summary

void	addToSendQueue(java.io.Serializable msg) Add a message to the send queue.
void	endOfUpdateFrame() Indicates that queued messages can be sent through to the client.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

allClientsClientIdToClientsImmutable

public final java.util.Map<java.lang.Integer,Client> allClientsClientIdToClientsImmutable

callBacks

public final RemoteHRDServerCallBacks callBacks

stateManager

public final StateManager stateManager

See notes above.

Constructor Detail

RemoteHRDServer

public RemoteHRDServer(java.net.ServerSocket serverSocket,
                       java.net.ServerSocket inputSourceServerSocket,
                       RemoteHRDServerCallBacks callBacks,
                       boolean alwaysServerPush)

Creates a RemoteHRDServer and starts the listening thread. This constructor returns immediately.

Parameters:

serverSocket -

callBacks -

alwaysServerPush -

Method Detail

addToSendQueue

public void addToSendQueue(java.io.Serializable msg)

Add a message to the send queue. The message might not be sent until you call endOfBurst(). See notes above for more details. This method is thead-safe; it can be called from any thread.

Parameters:

msg -

endOfUpdateFrame

public void endOfUpdateFrame()

Indicates that queued messages can be sent through to the client. This method is thead-safe; it can be called from any thread.