I've gone over this myself...
Can you store it in the database?
Coordinating objects in memory across the cluster is a journey on itself.
-Eclipselink 2.1 offers JPA 2.1 cache coordination in a cluster, And i think also Hibernate.
-There is an Oracle implementaion of JCache called Oracle TimesTen (very expensive). It basically synchronizes in memory data in a cluster..
-Another way of talking between clustered EJB containers is through JMS and MessageDrivenBeans. Every time the password changes, you could broadcast it via JMS Publish / Subscribe to MDB that update the Singletons...
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