Event Driven and Asynchronous Architecture Questions

Designing and operating systems that decouple components using asynchronous messaging and event driven patterns. Covers message queues and brokered communication models (for example Kafka, RabbitMQ, Amazon SQS), publish subscribe patterns, producer consumer workflows, background job and task queue design, and when to prefer asynchronous versus synchronous request response interactions. Includes higher level architectural patterns such as event sourcing, Command Query Responsibility Segregation, sagas for distributed transactions, and patterns for decoupling services. Operational concerns include delivery semantics (at least once, at most once, exactly once), ordering guarantees and partitioning, dead letter queues, retry strategies, idempotency, error handling, monitoring and alerting (for example message lag, queue depth), scaling consumers, throughput and latency trade offs, consistency implications, and common use cases such as email sending, batch processing, file processing, notification delivery, and distributed work coordination.