Stream - Message Queue System

Message Queue System is one type of implementation of a messaging system

It's a stream source

• RabbitMQ,
• Beanstalkd,
• ActiveMQ,
• IBM MQ Series,
• Tuxedo
• Amazon SQS

• 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.

• http://stackoverflow.com/questions/2383912/message-queue-vs-web-services