WSO2 SP is deployed by starting two or more nodes with the same group ID in a cluster set up. The group ID and other configurations required for a cluster set up are edited in the
A node is considered inactive when it fails to return a heartbeat pulse twice at a specified time interval. When an inactive node is identified, it is removed from the cluster. If that node becomes active again and rejoins the cluster, it is assigned a new ID. Therefore, at any given time, a cluster may have one or more active nodes. If all the nodes in a cluster are inactive, the cluster is considered inactive.
When a node with a specific group ID is started in a clustered setup, it registers itself as a member of the cluster identified by that group ID. If no other active node is available in that cluster, the node assigns itself as the leader of the cluster. If the leader of the cluster becomes inactive at any given time, an existing active node is assigned as the leader. The node assigned as the new leader is the one that acquires the database lock first. If a leader node that was inactive and removed from the cluster rejoins the cluster as an active member, it is not reassigned the role of the leader unless there are no other existing active nodes in that cluster (in which case, an existing node should be already functioning as the leader).
For detailed instructions to configure different types of WSO2 SP clusters, see the topics below.