RabitMQ - has libraries for favorite programming languages, and frameworks like spring, interface for web monitoring
RabbitMQ speaks the AMQP protocol by default.
Structure
Publisher (Producer) - Publishes message to Message Broker
Message Broker - RabbitMQ [Exchange, [Queue, ..] ]
Exchange receives messages and directs them to the correct queue
Exchange type:
- Direct - sends depending on binding key.
- Topic - sends based on wildcard.
- Fanout - sends all queue, that ar bound to it.
Features:
- Durable
- exchanges will survive server restarts and will last until they are explicitly deleted.
- Temporary
- exchanges exist until RabbitMQ is shutdown.
- Auto deleted
- exchanges are removed once the last bound object unbound from the exchange.
Consumer - Consumes data. Subscribes.
- Client applications called producers that create messages and deliver them to the broker (the message queue)
- Other applications, called consumers, connects to the queue and subscribes to the messages to be processed. Messages that are placed onto the queue are stored until the consumer retrieves them.
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 or subscribing to a queue, it
is 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.
AMQP: AMQP (Advanced Message Queuing Protocol) is the main
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 vhosts and queues, and exchanges
can be created so they only exist in one vhost.
Process
- Set up connection.(Username, password)
- Open channel in tcp connection.
- Declare/create a queue
- Subscriber/Consumer - Set up exchanges and bind a queue to an exchange. For messages to be routed to queue, queue need to be bound to exchange
- Publisher: Publish message to echange
- Subscriber/Consumer - Consume a message from queue.
- Close the channel and the connection
Resources:
cloudamqp.com - cloudAMQP
Installing rabitmq:
https://www.digitalocean.com/community/tutorials/how-to-install-and-manage-rabbitm
rabitmq status:
$ service rabbitmq-server status
enabling service:
$ chkconfig rabbitmq-server on
enable plugins:
$ sudo rabbitmq-plugins enable rabbitmq_management
cmd commands:
List exchanges:
$ sudo rabbitmqctl list_exchange
By default you can't login to remote console from external non-local.
How to enable logging from remote machine to rabitmq console:
$ rabbitmqctl add_user YOUR_USERNAME YOUR_PASSWORD
$ rabbitmqctl set_user_tags YOUR_USERNAME administrator
$ rabbitmqctl set_permissions -p / YOUR_USERNAME ".*" ".*" ".*"
Problem:
By default rabitmq blocks loggins from remote ip adresses. How to enable remote login?
Solution:
Goto /etc/rabbitmq folder and create rabbitmq.conf with file content:
