Messaging concepts

The following is a list of concepts that relate to messaging:

• Producer: Application that sends the messages.
• Consumer: Application that receives the messages.
• Queue: Buffer that stores messages.
• Message: Information that is sent from the producer to a consumer through RabbitMQ.
• Connection: A connection is a TCP connection between your application and the RabbitMQ broker.
• Channel: A channel is a virtual connection inside a connection. When you are publishing or consuming messages from a queue - it's all done over a channel.
• Exchange: Receives messages from producers and pushes them to queues depending on rules defined by the exchange type. In order to receive messages, a queue needs to be bound to at least one exchange.
• Binding: A binding is a link between a queue and an exchange.
• Routing key: The routing key is a key that the exchange looks at to decide how to route the message to queues. The routing key is like an address for the message.
•  Advanced Message Queuing Protocol (AMQP): AMQP is the protocol used by RabbitMQ for messaging.
• Users: It is possible to connect to RabbitMQ with a given username and password. Every user can be assigned permissions such as rights to read, write, and configure privileges within the instance. Users can also be assigned permissions to specific virtual hosts.
• Vhost: A virtual host provides a way to segregate applications using the same RabbitMQ instance. Different users can have different access privileges to different vhosts and queues, and exchanges can be created so they only exist in one vhost.