Build an Event-Driven Integration

TimeUnder 10 minutes

What you'll buildAn event-driven integration that consumes messages from Orders queue in RabbitMQ broker and processes them.

Event integrations are designed for reactive workflows triggered by messages from a broker. This quick start demonstrates the complete flow: creating a RabbitMQ message listener, adding an event handler to process messages, and implementing the integration logic executed when a message is received.

Prerequisites

A working WSO2 Integrator environment.

WSO2 Cloud setup

RabbitMQ

A running instance, or start one with Docker:

Step 1: Create the integration

Note

In the cloud editor, you're already inside a project. Skip to Step 2.

Open WSO2 Integrator.
Select the Create New Integration card.
Set Integration Name to OrderProcessor.
Set Project Name to event-integration.
Select Create Integration.

Step 2: Add a RabbitMQ event listener

Select your integration from the project overview canvas.
Select + Add Artifact in the design canvas.
Select RabbitMQ under Event Integration.
Set Host to localhost and Port to 5672 (update these if your RabbitMQ instance runs elsewhere).
Set Queue Name to Orders.
Select Create.

Add a RabbitMQ Event Integration Artifact

Step 3: Add `onMessage` event handler

In the RabbitMQ service design view, select + Add Handler.
Select onMessage.
Select Save.

Step 4: Add message processing logic

Select + inside the resource flow.
Select Call Function.
Select printInfo under log.
Set Msg to Received order.
Select Save.

Step 5: Run and test the integration

Select Run.
The integration starts and listens for messages on the Orders queue.
Open the RabbitMQ Management UI at http://localhost:15672 (default credentials: guest/guest).
- Go to Queues → Orders → Publish message, enter any text as the payload, and select Publish message.
- Confirm the integration log displays Received order.

Step 6: Deploy to WSO2 Cloud

Deploy your integration to WSO2 Cloud. Check Save and deploy.

Skip ahead: deploy a ready-made sample

Rather not build it yourself? One-click deploy the OrderProcessor sample straight to WSO2 Cloud.

Source code

View the generated Ballerina code

The steps above generate the following complete, runnable Ballerina program:

import ballerina/log;
import ballerinax/rabbitmq;

listener rabbitmq:Listener rabbitmqListener = new ("localhost", 5672);

service "Orders" on rabbitmqListener {
    remote function onMessage(rabbitmq:AnydataMessage message, rabbitmq:Caller caller) returns error? {
        do {
            log:printInfo("Received order");
        } on fail error err {
            // handle error
            return error("unhandled error", err);
        }
    }
}

Supported event sources

Broker	Ballerina Package
Apache Kafka	`ballerinax/kafka`
RabbitMQ	`ballerinax/rabbitmq`
MQTT	`ballerinax/mqtt`
Azure Service Bus	`ballerinax/azure.servicebus`
Salesforce	`ballerinax/salesforce`
GitHub Webhooks	`ballerinax/github`

Learn more

Kafka — Consume and produce Kafka messages
Azure Service Bus — Integrate with Azure Service Bus queues and topics
RabbitMQ — Full RabbitMQ listener and publisher reference
MQTT — Handle MQTT messages from IoT and messaging devices
CDC for PostgreSQL — React to database changes with change data capture

Prerequisites​

Step 1: Create the integration​

Step 2: Add a RabbitMQ event listener​

Step 3: Add onMessage event handler​

Step 4: Add message processing logic​

Step 5: Run and test the integration​

Step 6: Deploy to WSO2 Cloud​