(Message Oriented Middleware) Software plumbing. Message-oriented middleware is the term for software that connects separate systems in a network by carrying and distributing messages between them. The messages may contain data, software instructions, or both together. MOM infrastructure is typically built around a queuing system that stores messages pending delivery, and keeps track of whether and when each message has been delivered. Most MOM systems also support autonomous publish-subscribe messaging. MOM products frequently use proprietary messaging technologies -- well-known examples include IBM MQSeries, MSMQ from Microsoft and Tibco Rendezvous -- but emerging standards specifications such as JMS and WS-ReliableMessaging are now enabling standards-based MOM infrastructures.