Service and Topology Tracking
- Users can subscribe for contents of and changes to the global address binding table.
- They receive an event at each change matching the range indicated in the subscription.
- There is a match when an bound/unbound instance or range overlaps with range subscribed for.
- Received events contain the bound/unbound socket’s service address and socket address.
Cluster Topology Tracking
- Cluster topology tracking is a special case of service tracking, also based on the binding table contents
- Peer node availability, as seen from the own node, is represented by the built-in service type 0.
- Cluster connectivity tracking is also possible by subscribing for availability of individual links, using the built-in service type 2.
- Using these mechanisms, and by connecting to other cluster nodes's topology servers, it is possible for a user to build and track the overall connectivity matrix of the whole cluster.
Group Membership Tracking
- Communication group members can optionally subscribe for join/leave/close/ /crash/lost-contact events for other group members.
- Membership events are received in a member socket in the form of out-of-band empty messages.
- Event order is guaranteed, - a join event always arrives before the first message from the new member, - a leave event always arrive after the last message from the leaving member. .