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Class JavaGroups.RequestCorrelator

java.lang.Object
   |
   +----JavaGroups.RequestCorrelator

public class RequestCorrelator

extends Object

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).

RequestCorrelator(String, Protocol, RequestHandler)

Constructor.

RequestCorrelator(String, Protocol, RequestHandler, boolean)

Constructor.

Done(long)

Used to signal that a certain request may be garbage collected as all responses have been received.

finalize()

main(String[])

Receive(Event)

Callback.

SendRequest(long, Message, RspCollector)

Send a request to a group.

SetDeadlockDetection(boolean)

SetRequestHandler(RequestHandler)

Start()

Stop()

 public RequestCorrelator(String name,
                          Protocol 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:

name - Used to differentiate between diferent RequestCorrelators (e.g. in different protocol layers). Has to be unique if multiple request correlators are used.

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.

 public RequestCorrelator(String name,
                          Protocol transport,
                          RequestHandler handler,
                          boolean deadlock_detection)

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

Parameters:

name - Used to differentiate between diferent RequestCorrelators (e.g. in different protocol layers). Has to be unique if multiple request correlators are used.

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.

deadlock_detection - When enabled (true) recursive synchronous message calls will be detected and processed with higher priority in order to solve deadlocks. Slows down processing a little bit when enabled due to runtime checks involved.

 public void finalize()

Overrides:

finalize in class Object

 public void SetDeadlockDetection(boolean flag)

 public void SetRequestHandler(RequestHandler handler)

 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.

 public void Done(long id)

Used to signal that a certain request may be garbage collected as all responses have been received.

 public void Receive(Event evt)

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, pass it up to the next layer. 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.

 public void Start()

 public void Stop()

 public static void main(String args[])

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