Chapter 5. Messaging Terms

An application that uses the message broker to communicate with other applications. These applications use one of the broker's client API to connect to and interact with the broker.

An application that consumes messages from a messaging destination.

An object that a client uses to create a connection to a broker. A factory supports attributes that configure the quality of service for the connections it creates.

A logical holding area for messages in a message broker. Clients publish messages to and consume messages from destinations.

See also: queue, topic

A message consumer that receives all messages published on a topic, including those published while the subscriber is inactive.

An atomic unit of data that is passed between two or more clients. A message consists of three components:

A string containing a boolean SQL statement using SQL 92 syntax that is used to select messages based on JMS message header properties.

A collection of JMS messages that are assigned the same JMSXGroupID.

When used in conjunction with the JMSXGroupSeq message groups can be used to ensure that messages are processed in the proper sequence.

A topology in which a single instance, the master, is active and one or more instances, the slaves, are ready to resume when the active instance stops.

An application that creates messages and posts them to a messaging destination.

A messaging style where messages are sent between two known endpoints. This messaging style is typically implemented using queues.

A messaging style where message producers send(publish) messages to a destination and interested consumers can register(subscribe) to receive messages from the destination. This style of messaging is implemented using topics.

A destination that uses first in/first out semantics.

See also: destination

A messaging pattern in which a message producer receives a message and returns a correlated message.

A JMS object that provides a single-threaded context for producing and consuming messages. JMS clients use the Session object to create producers, consumers, messages, and other artifacts used to work with messages.

A language agnostic, simple text-based protocol that allows clients to talk with any message broker supporting the protocol.

A standards-based network protocol, such as HTTP or STOMP, that defines how objects communicate over a network.

A destination that uses publish and subscribe semantics.

See also: destination

See advisory message

A special type of message that contains administrative information about the message broker. They are sent by the broker to special advisory topics.

See also: advisory topic

A group of special topics that are created by a message broker that are used for monitoring the state of the broker. The broker sends messages about a variety of internal broker events. Clients subscribing to these topics receive advisory messages about these objects.

An open source project that provides the messaging technology for Red Hat JBoss A-MQ.

See http://activemq.apache.org

A bridge between a client and a broker connector or between two brokers in a network of brokers.

See also: transport connector, network connector, network of brokers

An object that connects clients to a broker.

A virtual destination that serves as a proxy for multiple destinations. Producers can send messages to the composite destination an it will be automatically sent to all of the physical destinations that make up the composite destination.

See also: virtual destination

A special destination used by the message broker to hold undeliverable messages.

A mechanism for clients to become aware of the existence of brokers through the use of a discovery agent.

See also: discovery agent

A mechanism that advertises the list of available message brokers to message clients and other message brokers.

See also: dynamic discovery

A mechanism that ensures that only one consumer connected to a queue can consume messages.

A group of brokers that are linked together to operate as a single logical unit.

A configuration entity used to link brokers together to form a network of brokers.

See also: network of brokers

A runtime directional link between brokers that is used to forward messages. Network bridges are created by network connectors.

See also: network connector

A consumer that indicates to the topic that every attempt is to be made to send messages that the consumer may have missed.

A paradigm in which brokers receive messages, store them locally, and forwards the message to a recipient when it is able to do so. The message is only deleted once it has been successfully delivered.

An address at which a message broker accepts client connections.

A logical destination that represents one or more physical destinations.

See also: composite destination, virtual topic

A logical topic that allows consumers to use a physical queue to consume messages from the destination.

See also: virtual destination, topic, queue

A Java API implementing a messaging standard that allows application components based on J2EE to create, send, receive, and read messages. It enables distributed communication that is loosely coupled, reliable, and asynchronous.