cern.cmw.rda.client
Class SubscriptionRequest

java.lang.Object
  cern.cmw.rda.client.Request
      cern.cmw.rda.client.SubscriptionRequest

All Implemented Interfaces:

ISubscriptionRequest

public class SubscriptionRequest
extends Request
implements ISubscriptionRequest

Represents a data subscription request. A SubscriptionRequest is created and sent to a device server as a result of successful monitorOn call on a DeviceHandle object. It is always returned to the caller in the PENDING state.

The RDA client waits for replies to all pending subscription requests and takes the following actions on the following events:

• reply received
  Depending on the reply type, one the following two methods will be called on the associated ReplyHandler:
  • ReplyHandler.handleReply(Request,Data)
    to notify that the subscribed property value has been updated
  • ReplyHandler.handleException(Request,IOError)
    to notify that an attempt to update the subscribed property has failed due to an I/O error
• connection lost to the server
  The ReplyHandler.disconnected(SubscriptionRequest) method will be called on the ReplyHandler.
• connection restored
  The request will be resend to the server and the ReplyHandler.reconnected(SubscriptionRequest) method will be called on the ReplyHandler.

The request does not change its state in any of these events: it remains PENDING until explicitely cancelled by the monitorOff call. If the call succeeds, the ReplyHandler will be notified via the ReplyHandler.cancelled(SubscriptionRequest) method.

A SubscriptionRequest object will be deleted (garbage collected) if it is not PENDING and unreferenced in the user code.

Method Summary

int	getId()
boolean	isOnChange() Returns true if the on-change mode has been specified in the monitorOn call that created this request; false otherwise.

Methods inherited from class cern.cmw.rda.client.Request

getContext, getCycleSelector, getDeviceHandle, getPropertyName, isPending

Methods inherited from class java.lang.Object

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

Method Detail

getId

public int getId()

isOnChange

public boolean isOnChange()

Returns true if the on-change mode has been specified in the monitorOn call that created this request; false otherwise.