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’s 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
