MSMQ Glossary: C


Updated: July 19, 2016

Applies To: Windows 10, Windows 7, Windows 8, Windows 8.1, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, Windows Server Technical Preview, Windows Vista


See certification authority.

callback function

A function used to asynchronously read the messages in a queue. It is an application-defined function that Message Queuing calls when a message is available or an error (for example a time-out) occurs.

certification authority (CA)

An entity that issues certificates that are used as external certificates. The certification authority accepts requests for certificates, confirms that the information provided in the request is accurate, and returns a certificate to the person requesting it.

The requester must provide their public key and whatever additional information is required by the certification authority.

See also external certificate.

COM+ transaction

A transaction that uses a Component Services (COM+) context in MSMQ 2.0 and later. When using Message Queuing COM objects, Message Queuing can implicitly use the current COM+ transaction if one is available.


Computers are created and maintained by the Message Queuing administrator. All existing computers that belong to the domain are defined in the directory service.

A computer's properties can be retrieved using MQGetMachineProperties.

See also directory service.

computer GUID

A globally unique identifier (GUID) for a computer, which is generated by Message Queuing when the computer is added to your enterprise. (Same as "computer identifier.")

The GUID identifying a computer can be retrieved by a call to MQGetMachineProperties.

computer identifier

A globally unique identifier (GUID) for a computer, which is generated by Message Queuing when the computer is added to your enterprise. (Same as "computer GUID.")

The identifier of a computer can be retrieved by a call to MQGetMachineProperties.

computer journal

A system queue used to store copies of application-generated messages. This is also called machine journal and source journal.

See also queue journal.

computer name

The name of the computer where the queue's messages will be stored. Message Queuing supports both the NetBIOS name and full DNS name of the computer. Computer names are not case sensitive, so "mycomputer" and "MyComputer" are treated the same way.

To indicate the local computer, you can substitute the string "." for the name of the local computer. (For dependent clients, the local computer name is the name of the dependent client's supporting server.)

For private queues, the computer name must be the name of the local computer.

computer quota

The cumulative storage limit for all messages stored in destination queues, outgoing queues, and queue journals on a computer. When the computer quota is reached, no messages can be delivered to any queue or journal on the computer.

computer system queue

One of the three system-generated queues associated with the computer. The keywords for these queues are JOURNAL, DEADLETTER, or DEADXACT.

See also direct format name.

connector application

An application that runs on an MSMQ connector server and translates both outgoing and incoming messages sent between a Message Queuing computer and a foreign messaging system.

Connector applications may also perform security services such as authenticating messages and encrypting/decrypting messages.

connector queue

A queue used by an MSMQ connector server. Messages sent to foreign queues are temporarily stored in a connector queue before they are retrieved by the connector application.

Connector servers can have several pairs of connector queues. Message Queuing creates a transactional and a nontransactional queue on a connector server for each foreign site connected to it.

connector server

A Message Queuing routing server that is configured to send messages between a Message Queuing enterprise and one or more foreign sites. A connector server has a connector application running on it and two connector queues for each foreign site: one used for transactional messages and one used for nontransactional messages.

correlation identifier

A 20-byte identifier used to identify a message. The correlation identifier message property can be set by Message Queuing (when generating acknowledgement and report messages) or by the sending application.

The correlation identifier must be exactly 20-bytes in length.

critical section object

A Win32® object that provides mutually exclusive synchronization within a process. A critical section object can only be used by one thread at a time.

For more information on critical section objects, see the Platform SDK and winbase.h.


A mechanism that receiving applications can use to maintain a specific location when navigating through a queue. Each cursor is associated with a specific instance of an open queue.