In a microservices-based e-commerce system you need a messaging backplane for transactional messages between components. Messages must be delivered in first-in, first-out (FIFO) order. Which Azure service should you select?

Azure Service Bus is the correct choice because it offers advanced messaging capabilities, including guaranteed message delivery, transactional support, and FIFO ordering for messages within a session. These features are crucial for reliable transactional communication in a microservices architecture. Azure Storage Queue is a simpler queueing service primarily for basic asynchronous message processing and does not inherently guarantee FIFO order or transactional integrity across multiple operations. Azure Event Hub is designed for high-throughput data streaming and event ingestion, not for transactional messaging between services. Azure Event Grid is an event routing service for reactive programming and event-driven architectures, not a message broker for transactional communication.