Mark Brouwer wrote:
2) do you think it is essential a client must be able to find out whether an event producer is able to deliver events at all;
In my industry we call these "health check" events. At regular, known intervals, a remote field device, which is using a "Report by Exception" event delivery instead of a "poll at interval" discovery model, will send it current state to the listeners/subscribers.
It's the leased type of relationship that helps notify technicians of equipment failure. In one application, I did send a remote Lease reference to the other end to let me know when that end disappeared and would no longer be sending me events. This also covers the callback scenario in a general since of network reachability/routabilty in that if the callback on the Lease renew won't work, then probably the callback for notification won't either.
Gregg Wonderly
