AWS Certified Solutions Architect – ProfessionalDesign Solutions for Organizational ComplexityMedium

A global banking institution operates a mission-critical, mainframe-based payment processing system that cannot be immediately migrated to AWS due to its complexity and regulatory constraints. However, they want to integrate new cloud-native microservices with this mainframe to build modern customer-facing features. The integration requires reliable, asynchronous communication with guaranteed message delivery and exactly-once processing to ensure financial transaction integrity. Which AWS service should a Solutions Architect recommend to facilitate this hybrid integration?

  1. AAmazon SQS for asynchronous messaging between microservices and the mainframe.
  2. BAmazon Kinesis Data Streams for real-time data ingestion and processing.
  3. CAWS API Gateway to expose mainframe APIs as REST endpoints for microservices.
  4. DAmazon MQ for Apache ActiveMQ to provide a managed message broker.
Show answer & explanation

Correct answer: A. Amazon SQS for asynchronous messaging between microservices and the mainframe.

Amazon SQS provides a highly scalable, fully managed message queuing service that supports asynchronous communication, guaranteed message delivery, and exactly-once processing (with FIFO queues). This makes it ideal for integrating cloud-native microservices with a legacy mainframe system where reliable, transactional message exchange is critical for financial integrity without tightly coupling the systems.

Why the other options are wrong

  • B. Amazon Kinesis Data Streams is designed for real-time processing of large streams of data. While it offers high throughput, it's for streaming data analytics rather than transactional messaging with exactly-once delivery guarantees between distinct application components.
  • C. AWS API Gateway is used to create, publish, maintain, monitor, and secure REST, HTTP, and WebSocket APIs. While it can expose mainframe APIs, it's primarily for synchronous request-response interactions and doesn't inherently provide the asynchronous, guaranteed delivery, or exactly-once processing required for transactional integrity in this scenario.
  • D. Amazon MQ provides managed message brokers compatible with Apache ActiveMQ and RabbitMQ. While it offers message queuing, for integrating with cloud-native microservices, Amazon SQS is often preferred for its fully managed, serverless nature and native support for guaranteed delivery and exactly-once processing (with FIFO queues), simplifying operations compared to managing brokers.

Amazon SQS (Simple Queue Service)

A fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.

  • Supports asynchronous communication between components.
  • Offers standard queues (at-least-once delivery) and FIFO queues (exactly-once processing, message ordering).
  • Eliminates the need to manage message broker infrastructure.

Memory trick: SQS: Simple Queues for Seamless System Sync.

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