Listener clustering

Clustering involves the use of multiple listeners for the purpose of high availability and load balancing.

Clustered listeners ensure that failover occurs automatically from one machine to another. Additionally, clustered listeners provide parallel processing and load balancing, for improved performance.

Listener clustering, also referred to as back-end clustering, is important because flowchart runs happen at the back end. Flowchart runs create and update contact history, offer history, and other configured tables.

When multiple listeners are configured as a cluster, the front-end web application communicates over TCP/IP with all listener nodes. Within the cluster itself, one node acts as the master listener, and is responsible for performing load balancing of client requests across the nodes.

Listener clustering provides the following benefits:

  • Stability: Multiple listeners run in parallel across multiple machines in the cluster.
  • Load balancing: The back-end load is shared across listener nodes, using weighted round robin to distribute the load.
  • Failover: If a listener goes down due to hardware, software, or network failure, failover occurs automatically, minimizing disruption.
  • Scalability: Additional nodes can be added to run additional listeners.