java.lang.Object
- org.astrogrid.samp.client.AbstractMessageHandler
- - org.astrogrid.samp.client.ClientTracker

All Implemented Interfaces:

MessageHandler
```
class ClientTracker
extends AbstractMessageHandler
```
Message handler which watches hub event messages to keep track of what clients are currently registered and what their attributes are on behalf of the hub. The results are stored in an externally supplied TrackedClientSet object. This class tries its best to handle complications arising from the fact that calls concerning a client may arrive out of order (for instance declareMetadata before registration or after unregistration).

Since:

16 Jul 2008

Author:

Mark Taylor, Laurent Bourges

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`private static class`	`ClientTracker.ClientOperation`	Describes an operation to be performed on a TrackedClient object which is already part of this tracker's model.
`private static class`	`ClientTracker.OperationQueue`	Data structure for holding ClientOperation objects which (may) need to be applied in the future.
`private static class`	`ClientTracker.TrackedClient`	Client implementation used to populate internal data structures.

Field Summary

Fields
Modifier and Type	Field	Description
`private java.util.Map`	`clientMap_`
`private TrackedClientSet`	`clientSet_`
`private static java.util.logging.Logger`	`logger_`
`private static java.lang.String`	`METADATA_MTYPE`
`private ClientTracker.OperationQueue`	`opQueue_`
`private static int`	`QUEUE_TIME`
`private static java.lang.String`	`REGISTER_MTYPE`
`private static java.lang.String`	`SUBSCRIPTIONS_MTYPE`
`private static java.lang.String[]`	`TRACKED_MTYPES`
`private static java.lang.String`	`UNREGISTER_MTYPE`

Constructor Summary

Constructors
Constructor Description

ClientTracker(TrackedClientSet clientSet)
Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`clear()`	Removes all clients from the list.
`void`	`initialise(HubConnection connection)`	Initialises this tracker from a hub connection.
`private void`	`performClientOperation(ClientTracker.ClientOperation op, HubConnection connection)`	Performs an operation on a ClientOperation object.
`java.util.Map`	`processCall(HubConnection connection, java.lang.String senderId, Message message)`	Implements message processing.

Methods inherited from class org.astrogrid.samp.client.AbstractMessageHandler
createResponse, getSubscriptions, receiveCall, receiveNotification, setSubscriptions

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - clientSet_
```
private final TrackedClientSet clientSet_
```
  - clientMap_
```
private final java.util.Map clientMap_
```
  - opQueue_
```
private final ClientTracker.OperationQueue opQueue_
```
  - logger_
```
private static final java.util.logging.Logger logger_
```
  - QUEUE_TIME
```
private static final int QUEUE_TIME
```
    See Also:
    
    Constant Field Values
  - REGISTER_MTYPE
```
private static final java.lang.String REGISTER_MTYPE
```
  - UNREGISTER_MTYPE
```
private static final java.lang.String UNREGISTER_MTYPE
```
  - METADATA_MTYPE
```
private static final java.lang.String METADATA_MTYPE
```
  - SUBSCRIPTIONS_MTYPE
```
private static final java.lang.String SUBSCRIPTIONS_MTYPE
```
  - TRACKED_MTYPES
```
private static final java.lang.String[] TRACKED_MTYPES
```
- Constructor Detail
  - ClientTracker
```
public ClientTracker(TrackedClientSet clientSet)
```
    Constructor.
    
    Parameters:
    
    clientSet - object used to record registered clients and their attributes
- Method Detail
  - clear
```
public void clear()
```
    Removes all clients from the list.
  - initialise
```
public void initialise(HubConnection connection)
                throws SampException
```
    Initialises this tracker from a hub connection. It is interrogated to find the current list of registered clients and their attributes.
    
    Parameters:
    
    connection - hub connection; may be null for no connection
    
    Throws:
    
    SampException
  - processCall
```
public java.util.Map processCall(HubConnection connection,
                                 java.lang.String senderId,
                                 Message message)
```
    Description copied from class: AbstractMessageHandler
    
    Implements message processing. Implementations should normally return a map which contains the samp.result part of the call response, that is the MType-specific return value name->value map. As a special case, returning null is equivalent to returning an empty map. However, if AbstractMessageHandler.createResponse(java.util.Map) is overridden, the return value semantics may be different.
    
    Specified by:
    
    processCall in class AbstractMessageHandler
    
    Parameters:
    
    connection - hub connection
    
    senderId - public ID of sender client
    
    message - message with MType this handler is subscribed to
    
    Returns:
    
    result of handling this message; exact semantics determined by createResponse implementation
  - performClientOperation
```
private void performClientOperation(ClientTracker.ClientOperation op,
                                    HubConnection connection)
```
    Performs an operation on a ClientOperation object.
    
    Parameters:
    
    op - client operation
    
    connection - hub connection

Class ClientTracker

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.astrogrid.samp.client.AbstractMessageHandler

Methods inherited from class java.lang.Object

Field Detail

clientSet_

clientMap_

opQueue_

logger_

QUEUE_TIME

REGISTER_MTYPE

UNREGISTER_MTYPE

METADATA_MTYPE

SUBSCRIPTIONS_MTYPE

TRACKED_MTYPES

Constructor Detail

ClientTracker

Method Detail

clear

initialise

processCall

performClientOperation