Stream - Message Queue System
About
Message Queue System is one type of implementation of a messaging system
It's a stream source
Articles Related
Implementation
RabbitMQ,
Beanstalkd,
ActiveMQ,
IBM MQ Series,
Tuxedo
Amazon SQS
Characteristics
If the server fails, the queue persist the message (optionally, even if the machine shutdown).
When the server is working again, it receives the pending message.
If the server gives a response to the call and the client fails, if the client didn't acknowledge the response the message is persisted.
You have contention, you can decide how many requests are handled by the server (call it worker instead).
You don't expect an immediate synchronous response, but you can implement/simulate synchronous calls.
You can handle error conditions yourself or leave them to the message queue.
Documentation / Reference