Message Oriented Middleware: QPID ActiveMQ RabbitMQ OpenAMQ ZeroMQ

Introduction to Message Oriented Middleware

Message Oriented Middleware or MOM concept involves the exchange of data between different applications using messages. In a MOM,  messages are usually sent and received asynchronously (as compared to RPC-style communications which tend to be synchronous in nature). Using  this mechanism, applications are decoupled and senders and receivers exist without the knowledge of each other. It becomes the responsibility of the messaging system (Message Oriented Middleware) to transfer the messages between applications.

Message Oriented Middleware Concepts

Message Structure

A message can have two parts: header and body. The headers are used by both the messaging system and the application developer to provide information about things such as the destination, the message type etc.

The format of the message body depends on messaging implementations. Common formats include plain text, a raw stream of bytes or a XML message that can be understood via XML parsing technologies.

Broker

MOM acts as message broker and  manages the connections and channels of communication between multiple clients. It can route, transform, aggregate or store messages.

Client

This is the end point application that is capable of communicating with the Message Oriented Middleware in the format and language that is understood by the broker.

Message Oriented Middleware Communication Models:

Publish-and-subscribe

This is intended for a one-to-many broadcast of information. Here multiple consumers register to a particular type of message/communication channel. A producer can send the message on that registered channel such that each subscriber receives a copy of that message.

Point-to-Point

This is intended for a one-to-one communication between two specific applications.

Round-Robin

This is intended for distribution of tasks equally among recipients for load balancing.

Standards for Message Oriented Middleware architecture:

Advanced Message Queuing Protocol (AMQP)

AMQP allows vendor neutrality and supports request-response or point to point,publish-and-subscribe and round-robin messaging patterns.

JAVA Messaging Service (JMS)

This  standard allows applications based on the Java 2 Platform, Enterprise Edition (J2EE) to create, send, receive, and read messages. It allows the communication to be loosely coupled, asynchronous and reliable. It supports point to point and publish and subscribe messaging patterns. JMS standard does not define the format of the messages exchanged, so JMS systems are not inter operable.

Apache QPID vs ActiveMQ vs RabbitMQ vs OpenAMQ vs ZeroMQ (Comparing some opensource / Freeware options)

Continued….