Message brokers

Message brokers

  • a message broker accepts and forwards messages
  • allows applications to communicate via a queuing mechanism
  • a program that sends messages is a producer
  • a queue is essentially a large message buffer
  • many producers can send messages that go to one queue, and many consumers can try to receive data from one queue
  • a consumer is a program that mostly waits to receive messages

Use cases

  • Point-to-point messaging
  • Publish/subscribe - event-driven architecture-based system, where applications have fewer dependencies between each other
  • Long-running tasks and crucial API like preparing files to download
  • Microservices - to create event-based communication and use the message broker together with publish/subscribe pattern instead of REST APIs
  • Transactional systems - where we have several actions that need to be made after each previous one completes

Advantages

  • Improved system performance by introducing asynchronous processing
  • Increased reliability by guaranteeing the transmission of messages
    • In case of consumer failure, it can redeliver the message immediately or after some specified time

Disadvantages

  • Increased system complexity
    • maintaining the network between components or security issues
    • problem related to eventual consistency where some components could not have up-to-date data until the messages are propagated and processed
  • Debugging can be harder
  • There‚Äôs a steep learning curve at first
    • size of queues and messages, the behavior of queues, delivery settings or messages TTL

Amazon SQS & SNS

  • you can combine Amazon SNS power of publishing to multiple recipients with Amazon SQS durable queues

Examples

Sources