The lack of data versioning makes this unreliable as you may invalidate remote data, which may be newer than the data you're inserting on your node due to race conditions.
optimistic locking provides data versioning which gets you around this.
Thanks for the reply. I guess my problem was that I assumed that even though it was invalidation only I thought that perhaps jbossCache would still send around a token or something that other nodes could lock on but it appears that is not the case so to sum up because of that Invalidation with Pessimistic locking would be an invalid configuration for any use right?
Not any use, there would still be some cases where this is valid, e.g., with very frequently changing data (e.g., every few mins) where absolute correctness is not an issue since it changes that fast.