Messaging — Decoupling Applications

Decoupling components with messaging makes systems more resilient and scalable.

Amazon SQS (Simple Queue Service):

Fully managed message queue

Producers send messages; consumers poll and process

Messages retained up to 14 days

Standard queue: at-least-once delivery, best-effort ordering

FIFO queue: exactly-once processing, strict ordering

Dead Letter Queue (DLQ): store failed messages for analysis

Amazon SNS (Simple Notification Service):

Pub/Sub messaging; one message → many subscribers

Publishers push to topics; subscribers receive (email, SMS, Lambda, SQS, HTTP)

Use case: send same notification to multiple systems simultaneously

Amazon EventBridge:

Serverless event bus; route events between AWS services and SaaS apps

Replaces CloudWatch Events; more powerful

Amazon Kinesis:

Real-time data streaming; collect, process, analyze streaming data

Use cases: clickstream data, IoT telemetry, log data, video streams

SQS vs. SNS: SQS = one consumer processes each message (pull). SNS = many consumers get the same message (push). Often used together: SNS fanout → multiple SQS queues.

Reference:

Wikipedia: AWS

https://en.wikipedia.org/wiki/Amazon_Web_Services