Microsoft Message Queuing (MSMQ)

Message Queuing (MSMQ) technology enables applications running at different times to communicate across heterogeneous networks and systems that may be temporarily offline. Applications send messages to queues and read messages from queues. The following illustration shows how a queue can hold messages that are generated by multiple sending applications and read by multiple receiving applications.

Microsoft Message Queuing or MSMQ is a message queue implementation developed by Microsoft and deployed in its Windows Server operating systems since Windows NT 4 and Windows 95. The latest Windows 8 also includes this component. In addition to its mainstream server platform support, MSMQ has been incorporated into Microsoft Embedded platforms since 1999 and the release of Windows CE 3.0.

MSMQ is essentially a messaging protocol that allows applications running on separate servers/processes to communicate in a failsafe manner. A queue is a temporary storage location from which messages can be sent and received reliably, as and when conditions permit. This enables communication across networks and between computers, running Windows, which may not always be connected. By contrast, sockets and other network protocols assume that direct connections always exist.

MSMQ is responsible for reliably delivering messages between applications inside and outside the enterprise. MSMQ ensures reliable delivery by placing messages that fail to reach their intended destination in a queue and then resending them once the destination is reachable. It also supports security and priority based messaging. Dead letter queues can be created for looking at messages which timed out or failed for other reasons.

MSMQ also supports transactions. It permits multiple operations on multiple queues, with all of the operations wrapped in a single transaction, thus ensuring that either all or none of the operations will take effect. Microsoft Distributed Transaction Coordinator (MSDTC) supports transactional access to MSMQ and other resources.

Message Queuing provides guaranteed message delivery, efficient routing, security, and priority-based messaging.

It can be used to implement solutions to both asynchronous and synchronous scenarios requiring high performance. The following list shows several places where Message Queuing can be used.

• Mission-critical financial services: for example, electronic commerce.

• Embedded and hand-held applications: for example, underlying communications to and from embedded devices that route baggage through airports by means of an automatic baggage system.

• Outside sales: for example, sales automation applications for traveling sales representatives.

• Workflow: Message Queuing makes it easy to create a workflow that updates each system. A typical design pattern is to implement an agent to interact with each system. Using a workflow-agent architecture also minimizes the impact of changes in one system on the other systems. With Message Queuing, the loose coupling between systems makes upgrading individual systems simpler.