Hi, Pascal.

>This reservation system is really a great idea, probably too complex to be used at all time or not suitable in every situation but it surely can be very usefull and is far more elegant the locking (be it optimistic or pessimistic)....

It is really not that difficult once you get used to it. I wrote the first version of this in C on a Unix system some few geological eras ago... <s>

I implemented several versions of the same scheme with different levels of complexity. But a basic version is something that can take any of you just a couple hours to code. What can get complicated is to refactor an existing application using lots of pessimistic locking. For an app using optimistic concurrency control only, in the need to start applying something like this gradually, is not difficult at all.

Regards,