This figure shows an Oracle CEP high availability multi-server domain with one active and two primaries. The input streams are connected to all servers. Only the primary outputs events to the output streams. Each secondary buffers output events using an in-memory queue. All the servers belong to the same deployment group and notification group. Server 2 is the primary; servers 1 and 3 are secondaries. The primary outputs events to a JMS provider. The secondaries listen to the JMS provider to receive notification of the events that the primary publishes. The secondaries delete these published events from their in-memory queue.