Issue 8201 makes all operations of WS-E mandatory. After reconsideration and investigation, we think only subscribe/unsubscribe should be mandatory and others be optional. The reason is that in some cases when WS-E is composed with application services that manage the event source lifetime, WS-E is used only to establish an event subscription that can be terminated by either the subscriber or the event source. For this purpose, subscribe/unsubscribe are sufficient.  This would make WS-E very light-weighted yet quite useful.

In this subscribe/unsubscribe model,  any event subscription can have a life span of indefinite at event source, and this can be notified to the subscriber in the positive response message. With that, both event source and the subscriber know that there is no timer on the event subscription (huge reduction of complexity, no monitor logic, and no need to deal with time zone, date, duration, etc.). Event subscription is controlled by subscribe/unsubscribe for the subscriber, and the event source terminates the subscription by subscriptionEnd.

Proposal: 
1) make only subscribe and unsubscribe mandatory.
2) add policy assertions to indicate support of other optional operations.

Wu, Li