MicroProfile Reactive Messaging provides a reliable way to handle messages in reactive applications. MicroProfile Reactive Messaging ensures that messages aren’t lost by requiring that messages that were delivered to the target server are acknowledged after they are processed. Every message that gets sent out must be acknowledged. This way, any messages that were delivered to the target service but not processed, for example, due to a system failure, can be identified and sent again.

The application in this guide consists of two microservices, system and inventory. Every 15 seconds, the system microservice calculates and publishes events that contain its current average system load. The inventory microservice subscribes to that information so that it can keep an updated list of all the systems and their current system loads. You can get the current inventory of systems by accessing the /systems REST endpoint.

You will explore the acknowledgment strategies that are available with MicroProfile Reactive Messaging, and you’ll implement your own manual acknowledgment strategy. To learn more about how the reactive Java services used in this guide work, check out the "Creating reactive Java microservices" guide.

The Open Liberty Project team