...Someone mentioned JCS as a good solution - and it strikes me as being fairly simple to extend the JCS AbstractDiskCache (http://jakarta.apache.org/turbine/jcs/xref/org/apache/jcs/auxiliary/ disk/AbstractDiskCache.html.) I hope to start work on this in the short term - today or tomorrow ideally. Has anyone given this any more thought recently?...
From what we know of it, your application is certainly a good real-life test of the caching/persistent store system. Moving to JCS sounds like a very good idea, also because IIUC it won't require JDK 1.4 (as NIO would). Nothing against 1.4 but if there's a good solution that doesn't require it, all the better.
-Bertrand
