What is RabbitMQ?
Based on AMQP protocol, RabbitMQ is an open source message queuing broker which desired for intercommunication message passing between software components, achieving many capabilities which do not have out of the box with simple TCP sockets.
Install on Ubuntu (root privilege):
apt-get install rabbitmq-server
rabbitmq-plugins enable rabbitmq_management
wget http://localhost:15672/cli/rabbitmqadmin -o /opt/rabbitmqadmin
chmod +x /opt/rabbitmqadmin
apt-get install python2.7
default credentials for web interface: guest/guest
find the UI at: http://localhost:15672
Controlling rabbitmq by command line:
| rabbitmqctl stop | |
| rabbitmqctl status | |
| rabbitmqctl list_queues | |
| rabbitmqctl list_users | |
| rabbitmqctl list_bindings | |
| rabbitmqctl list_channels | |
| rabbitmqctl list_exchanges |
Connections
TCP connection from AMQP client.
Settings are configured from client.
Channels
From each connection one can have one of more channels.
Usually used to open a channel from each thread.
Settings are configured from client.
Exchanges
Entry point for queues. Exchange have a logic to send for queues the messages.
For instance message to one queue only, or broadcast to many queues.
Types:
- Direct
- Fanout
- Headers
- Topic
There is always default exchange which is direct. Name is empty string.
Queues
Contains messages at the end. This is the storage for messages.
Binding
Bind between exchange and queue.
Configurable from the server within Queues menu.
If you do not set any binding, the default binding is to the default exchange (AMQP default).
Note that several exchanges can be bound to queue, thus queue can get from many sources.
Diagram
Connection -> Channel -> Exchange -> Bind -> Queue
Java Implementation
With Spring – https://spring.io/guides/gs/messaging-rabbitmq/
one example, explains good: https://projects.spring.io/spring-amqp/
spring amqp reference: http://docs.spring.io/spring-amqp/reference/html/_reference.html
Further Reading
https://www.rabbitmq.com/tutorials/amqp-concepts.html
https://www.youtube.com/watch?v=ABGMjX4K0D8