Final answer:
IoT Hub is a cloud-based service that enables bi-directional communication between an IoT application and its connected devices, offering centralized message hub capabilities.
Step-by-step explanation:
The service you are asking about is IoT Hub. It is a managed service that is hosted in the cloud. This service provides a central message hub for bi-directional communication, which is crucial for effectively managing the interaction between an IoT application and the devices it is responsible for. With IoT Hub, you can register devices, send messages to those devices, and receive messages back, allowing for a highly integrated and efficient IoT ecosystem.