Redis Collections

The WebSEAL remote Redis session cache has the concept of 'collections' of replicated Redis servers to help with client-side partitioning of sessions.

Selection of the 'collection' which is to be used for a new session is based on the Host header found in the request – or a 'default' collection if no specific collection has been configured for the Host. This provides a sharding mechanism by which you can limit cross data centre traffic in a multi data centre environment.

When a session is created it will be created against the selected collection of Redis instances. The identifier for the collection will be included in the session cookie. If the client then switches to a different WebSEAL server, the identifier from the session cookie will be used to determine the correct collection of Redis instances to use.

This concept is further illustrated in the following diagram: