When a remote service pulls a CAS from an input queue for processing it first sends an ACK to the client identifying node IP and service PID.
It's been observed that sometimes the ACK is never received by the client. Interestingly, the process reply is received. In such a case, the UIMA-AS client should call onBeforeProcessCAS() if it handles a reply with no prior ACK. Some applications may depend on receiving onBeforeProcessCAS() and block if it never comes.