> ## Documentation Index
> Fetch the complete documentation index at: https://agenticbanking.backbase.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Build a connector that publishes events

> Build a custom connector from the template that publishes events to Sync Hub

Learn how to build a custom connector from the Grand Central connector template that publishes events to Sync Hub. Use this pattern when a source system produces data changes that downstream systems need to receive, for example account updates or payment status changes.

For the concepts behind this pattern, see [Event streaming](/platform/sync-hub/integration-patterns#2-event-streaming). For field-level detail on envelopes, headers, and properties, see [Sync Hub events and files reference](/platform/sync-hub/events-and-files-reference).

## Prerequisites

Before you start, make sure you have:

* A connector repository scaffolded from the connector template. For more information, see [Set up the project](/platform/developer-guides/build/set-up-the-project).
* Sync Hub deployed in your target runtime, with a topic for your events. For more information, see [Sync Hub deployment and configuration](/platform/sync-hub/deployment).
* Java and Maven installed for local builds.

## Build the connector

The template includes an event publish route that posts to the Sync Hub producer through the `gc-http-caller` Kamelet. You configure the route with properties instead of writing HTTP calls by hand.

1. Define the event contract. Decide the topic name, the event source domain, the schema version, and the payload shape inside the `data` object. Align these with the teams that consume the event.

2. Set the Sync Hub properties in the connector's `application.properties` file:

   ```properties theme={"system"}
   asb.event.type=com.backbase.party.event.spec.v1.PartyUpdateEvent
   asb.event.source=com.backbase.party
   asb.event.version=1.0.0
   asb.event.topic=party-updates
   asb.producer.apiUri=http://asb-producer.synchub-producer.svc.cluster.local
   ```

   The template route builds the publish endpoint as `${asb.producer.apiUri}/${asb.event.topic}/publish` and sets the `bbEventType` header from `asb.event.type`. The template hardcodes the `eventSource` header and derives `eventVersion` from the payload schema. In a production connector, set these headers from your own configuration, for example with the `asb.event.source` and `asb.event.version` properties.

   The `asb.event.type` value shown is an example. Use the event spec class that matches your event contract. Confirm the producer release name in the Application manifest for your runtime. Some runtimes deploy a versioned release name such as `asb-producer-v0`. For property descriptions, see [Connector properties](/platform/sync-hub/events-and-files-reference#connector-properties).

3. Implement the route logic: read from the source system, transform the payload into your event contract, and set the per-request values `identifier` and `traceParent` on the outgoing message. These values change for each event, so the connector sets them per request rather than in configuration. For route structure guidance, see [Anatomy of a connector](/platform/developer-guides/build/anatomy-of-a-connector).

4. Add the Sync Hub pod labels to the connector's `values.yaml` file so the runtime network policy allows the call to the producer:

   ```yaml theme={"system"}
   connector:
     customLabels:
       app.gcservices.io/synchub-enabled: "true"
       app.gcservices.io/synchub-type: "producer"
   ```

5. Build and run the connector locally:

   ```bash theme={"system"}
   mvn clean verify
   mvn quarkus:dev
   ```

## Verify the connector

To confirm the connector publishes events:

1. Trigger the route in your local or development environment.
2. Check the connector logs for a successful publish to the producer.
3. Check the producer logs in Grafana for the matching publish activity. For queries, see [Logs](/platform/sync-hub/monitoring#logs).
4. Confirm the message arrives on the topic with Azure Service Bus tooling. For more information, see [Service Bus explorer](/platform/developer-guides/run#service-bus-explorer).

## Next steps

* [Configure a custom connector](/platform/developer-guides/build/configure-connector): Secrets, properties, and traits for deployment.
* [Test and validate](/platform/developer-guides/build/test-and-validate): Add automated tests for your route.
* [Sync Hub go-live checklist](/platform/sync-hub/go-live-checklist): Verify your setup before production.