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Getting started

This page shows how to add jEAP Reaction Observer to a Spring Boot service so that the service's reactions to incoming messages are observed and published. For what the library actually records see How it works; for the broader context see System behaviour documentation.

1. Add the starter​

<dependency>
    <groupId>ch.admin.bit.jeap</groupId>
    <artifactId>jeap-reaction-observer-starter</artifactId>
</dependency>

The version is managed by the jEAP Spring Boot parent. The starter pulls in the messaging and events modules and registers the Spring Boot auto-configuration. The library is enabled by default.

2. Prerequisite: jEAP Messaging​

The observer publishes its events through jEAP Messaging, so a working jEAP Messaging configuration is required. In particular jeap.messaging.kafka.systemName and serviceName must be set, as they are used in the published events. The observer also reuses the Kafka JeapKafkaMessageCallback hooks of jEAP Messaging to detect produced and consumed messages — no business code changes are needed.

You do not need to declare message contracts for the reaction events; they are exempt from contract validation in jEAP Messaging.

3. Grant Kafka topic access​

The service needs write access to the two reaction topics of your platform's Reaction Observer Service instance, for example:

  • applicationplatform-reaction-identified
  • applicationplatform-reactions-observed

The applicationplatform prefix is specific to your Reaction Observer Service instance — ask the team operating it for the correct topic names. Configure your Kafka broker to allow this write access.

4. Configure the topics​

The topic names are the only required observer configuration (see the full Configuration reference):

jeap:
  reaction:
    observer:
      enabled: true   # default; set to false e.g. in integration tests
      events:
        reaction-identified-topic: applicationplatform-reaction-identified
        reactions-observed-topic: applicationplatform-reactions-observed

If jeap.reaction.observer.enabled is true (the default) both topic names are mandatory; startup fails with a clear error otherwise.

5. Run your application​

Start the service. The library tracks and emits events automatically. When it is active you will see:

INFO Starting ReactionsObservedEventScheduler