The Shibboleth V2 IdP and SP software have reached End of Life and are no longer supported. This documentation is available for historical purposes only. See the IDP v4 and SP v3 wiki spaces for current documentation on the supported versions.
The <ReplayCache> element configures the plugin used for the caching of message identifiers to prevent replay attacks. The only supplied cache implementation is a wrapper around a <StorageService> plugin.
On Version 2.4 and above, can be omitted, and a default/arbitrary StorageService will be used.