Application integration on AWS is a layered set of services. Amazon SQS is a managed message queue offering at-least-once delivery; Standard queues deliver in best-effort order with high throughput, while FIFO queues preserve order and exactly-once processing. Amazon SNS provides pub/sub fan-out, pushing messages to many subscribers such as SQS queues, Lambda functions, or HTTP endpoints. EventBridge builds on this with rich rules, a schema registry, and native ingestion of SaaS partner events, so it is the preferred choice when you need filtering or third-party event sources.
For high-volume real-time streams, Kinesis Data Streams captures millions of events per second and lets consumers replay data within a retention window, which makes it suitable for analytics, monitoring, and complex event processing. Kinesis Data Firehose is the zero-admin alternative that loads streams directly into S3, Redshift, or OpenSearch. Amazon MSK delivers managed Apache Kafka clusters for teams that already have Kafka expertise or want Kafka's exact semantics.
API Gateway is the front door for HTTP and REST APIs, handling throttling, authorization, request validation, and integration with Lambda or backend services. Auto Scaling works hand in hand with load balancers and compute fleets: it watches a CloudWatch metric and reacts through alarms and scaling policies. Target-tracking scaling aims to keep a chosen metric, like average CPU, at a target value; step scaling reacts to alarm breaches by adding or removing a fixed number of instances per step. The result is a self-adjusting capacity layer that does not require manual intervention.