Frequently Asked Questions

1.	What is the difference between a listener and a consumer?
2.	Is the WBEM client which sets up the subscription the same as the listener which receives the Indications ?
3.	In what order are Indications delivered to listeners?
4.	If the WBEM server fails and recovers, will my subscriptions still be there?

Answers

1.	A consumer is the application which actually handles an indication, possibly recording it, possibly displaying it to an operator. A listener is the destination to which an indication is sent by the WBEM server; the listener is known to the WBEM server, the consumer is not. Any number of consumers may be associated with a single listener.
2.	No. There are two distinct processes at work here ”the client uses the normal WBEM client/WBEM server interface to create the subscription on behalf of the CIM listener. The CIM listener then receives the indications. Although the two functions are distinct, there is, of course, no reason why they should not be implemented in the same software or in two software modules running on the same workstation.
3.	They may be delivered in any order; that event A occurred before event B or that Indication A' was created before Indication B' does not imply in any way that A' will be delivered before B'.
4.	The persistence of subscriptions (or instances of any class) across a failure is not discussed in the specification ”assume the worst, that they are gone and need to be recreated.