In previous releases of WebSphere® Application Server, the nonce was cached locally. WebSphere Application Server Versions 6 and later use distributed nonce caching. The distributed nonce cache makes it possible to replicate nonce data among servers in a WebSphere Application Server cluster.
If nonce elements are in a SOAP header, all nonce values are cached by the server in the cluster. If the distributed nonce cache is enabled, the cached nonce values are copied to other servers in the same cluster. Then, if the message with the same nonce value is sent to (one of) other servers, the message is rejected. A received nonce cache value is cached and replicated in a push manner among other servers in the cluster with the same replication domain. The replication is an out-of-process call and, in some cases, is a remote call. Therefore, there is latency when the content of the cache in the cluster is updated.
For more information, see the information that explains nonce cache timeout, nonce maximum age, and nonce clock skew in Token generator configuration settings.