I am prototyping a servlet to do order tracking. I am giving first considerations to how to persist the information. My first approach is to keep a file as well as a TreeMap. The TreeMap would be keyed by session id. I supposed if two sessions map to the same customer, we just write all of the data to a persistent ( bits and bytes ) and figure it out manually.

I am considering a round-robin file manager that has one file open for app, one file available for perusal and one buffer file that fits between them. The challenges of getting a disk to actually write are discussed in a post H2 in the Tips ( in the page linked by the post ) and I want to achieve 80+% reliability as a minimum design goal for 'get something working first'

Then we have the issue of moving active transactions from the TreeMap to the disk heads, be that as it may on the server. It is a somewhat involved thought arena and I wanted to solicit comments, suggestions, links thoughts and whatever else people may wish to comment. I understand Threading issues and synchronized access, I am at the slogging in first efforts phase and wish to allow others to provide observations.

Beginners welcome. My uplink is up only a few days at a time now so no-reply is not ignoring posters.