EXPLICIT_CLIENT_ACKNOWLEDGE
EXPLICIT_CLIENT_ACKNOWLEDGE
is like
CLIENT_ACKNOWLEDGE
except it acknowledges only the individual message, rather than all messages received so far on the session.
One example of when
EXPLICIT_CLIENT_ACKNOWLEDGE
would be used is when receiving messages and putting the information in a database. If the database insert operation is slow, you may want to use multiple application threads all doing simultaneous inserts. As each thread finishes its insert, it can use
EXPLICIT_CLIENT_ACKNOWLEDGE
to acknowledge only the message that it is currently working on.