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Rabbit MQ
Messages are not published directly to a queue, instead, the producer sends messages to an exchange. An exchange is responsible for the routing of the messages to the different queues. An exchange accepts messages from the producer application and routes them to message queues with the help of bindings and routing keys. A binding is a link between a queue and an exchange.
TYPES OF EXCHANGES
- Direct: A direct exchange delivers messages to queues based on a message routing key. In a direct exchange, the message is routed to the queues whose binding key exactly matches the routing key of the message. If the queue is bound to the exchange with the binding key xyz, a message published to the exchange with a routing key xyz is routed to that queue.
- Fanout: A fanout exchange routes messages to all of the queues that are bound to it.
- Topic: The topic exchange does a wildcard match between the routing key and the routing pattern specified in the binding.
- Headers: Headers exchanges use the message header attributes for routing.
RabbitMQ and server concepts
- 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. 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.
- AMQP: AMQP (Advanced Message Queuing Protocol) 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, virtual host: A Virtual host provides a way to segregate applications using the same RabbitMQ instance. Different users can have different access privileges to different vhost and queues and exchanges can be created, so they only exist in one vhost.
Hands on Experience with Example:
https://github.com/kuldeepsingh99/event-driven/
Reference :
rk_sehara 