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Class JavaGroups.RequestCorrelator 

java.lang.Object
   |
   +----JavaGroups.RequestCorrelator
public class RequestCorrelator
extends Object
implements Runnable
Framework to send requests and receive matching responses (matching on request ID). Multiple requests can be sent at a time. Whenever a response is received, the correct RspCollector is looked up (key = id) and its method ReceiveResponse invoked. A caller may use Done to signal that no more responses are expected, and that the corresponding entry may be removed.

RequestCorrelator can be installed at both client and server sides, it can also switch roles dynamically, i.e. send a request and at the same time process an incoming request (when local delivery is enabled, this is actually the default).

Constructor Index

o RequestCorrelator(Transport, RequestHandler)
Constructor.

Method Index

o Done(long)
Used to signal that a certain request may be garbage collected as all responses have been received.
o finalize()
o main(String[])
o Receive(Message)
Callback.
o run()
Remove requests from mq and invoke request_handler.Handle()
o SendRequest(long, Message, RspCollector)
Send a request to a group.
o SetRequestHandler(RequestHandler)
o Start()
o Stop()
o Suspect(Object)
Callback.

Constructors

o RequestCorrelator 
 public RequestCorrelator(Transport transport,
                          RequestHandler handler)
Constructor. Uses transport to send messages. If handler is not null, all incoming requests will be dispatched to it (via Handle(Message)).

Parameters:
transport - Use to send requests. Only Send is used, not Receive !
handler - Request handler. Method Handle(Message) will be called when a request is received.

Methods

o finalize 
 public void finalize()
Overrides:
finalize in class Object
o SetRequestHandler 
 public void SetRequestHandler(RequestHandler handler)
o SendRequest 
 public void SendRequest(long id,
                         Message msg,
                         RspCollector coll)
Send a request to a group. If no response collector is given, no responses are expected (making the call asynchronous).

Parameters:
id - The request ID. Must be unique for this JVM (e.g. current time in millisecs)
msg - The request to be sent. The body of the message carries the request data
coll - A response collector (usually the object that invokes this method). Its methods ReceiveResponse and Suspect will be invoked when a message has been received or a member is suspected, respectively.
o Done 
 public void Done(long id)
Used to signal that a certain request may be garbage collected as all responses have been received.

o Suspect 
 public void Suspect(Object mbr)
Callback. All response collectors currently registered will be notified that mbr may have crashed, so they won't wait for its response.

o Receive 
 public boolean Receive(Message msg)
Callback. Called by the protocol below when a message has been received. The algorithm should test whether the message is destined for us and, if not, return false. Otherwise, it should remove the header and check whether the message is a request or response. In the first case, the message will be delivered to the request handler registered (calling its Handle method), in the second case, the corresponding response collector is looked up and the message delivered.

o run 
 public void run()
Remove requests from mq and invoke request_handler.Handle()

o Start 
 public void Start()
o Stop 
 public void Stop()
o main 
 public static void main(String args[])

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