So, when executing operations inside a transatcion, are the data replicated with every write operation or only at the transatcion commit time? When is the transaction propagated to the other nodes in the cluster? Does something change if using asynchronous replication instead of synchronous?
if you're using optimistic transactions data gets only replicated at commit time: 2 messages are sent for sync caches (prepare + commit); 1 message for async cahes (commit).
if you're using pessimistic transactions, a remote messages (lock acquisiton) is sent on each operation.
More on transactions here: https://docs.jboss.org/author/display/ISPN/Infinispan+transactions