JGroups Protocol RELAY2
External
- http://www.jgroups.org/manual/html/user-advanced.html#RelayAdvanced
- http://www.jgroups.org/manual/html/user-advanced.html#Relay2Advanced
Internal
Overview
RELAY2 protocol was introduced to allow relaying (bridging) messages between two or more clusters.
The relaying mechanism works by establishing a "bridging cluster" between the participating local clusters. Each local cluster is "represented" by its coordinator, which is the only node in the local cluster that forwards messages to the coordinators of other clusters participating in the relaying process. In order to achieve this, each coordinator joins a parallel JGroups group, by using a different JGroups stack, initialized and started in addition to its main (local) JGroups stack.
A message sent to the bridging cluster reaches all its member, hence all participating clusters.
For two local clusters ("blue" and "red"), relaying works in both directions: messages passing between the members of cluster "blue" will be forwarded to cluster "red", eventually reaching all its members, while messages passing between the members of the cluster "red" will be forwarded to the cluster "blue"
In case a local coordinator dies TODO.
Configuration
This is an example of how to configure two Infinispan clusters to relay to each other: