I have a .NET application which integrates with Camunda to achieve a document approval workflow. I want to know how I can make Camunda notify my application once an approval step is completed? Should I use a Kafka connector in the BPMN to publish the approval event to a topic which my application subscribes to or is their a cleaner way to achieve this?
Great question! For integrating your .NET application with Camunda to receive notifications when approval steps are completed, you have several approaches to consider. Let me break down the options:
1. Kafka Connector Approach (Recommended)
This is indeed a clean and scalable solution:
How it works:
- Add a service task after your user task in the BPMN process
- Configure the Kafka Producer connector on this task
- Publish approval events (task ID, approval status, process data) to a Kafka topic
- Your .NET application subscribes to this topic and reacts to events
Advantages:
Real-time notifications- Decoupled architecture (asynchronous, scalable, resilient)
- Perfect for event-driven and microservices architectures
- Handles high throughput and provides message durability
2. HTTP Webhook Approach
How it works:
- Use an outbound HTTP connector or REST connector after the user task
- Make HTTP POST calls to your .NET application’s API endpoint
- Send task completion data directly to your application
Advantages:
- Real-time notifications
- Direct integration, no message broker needed
Disadvantages:
Tighter coupling between systems- Requires your .NET app to expose a public endpoint
- Less resilient to network issues
3. REST API Polling
How it works:
- Your .NET application periodically polls Camunda’s Tasklist or Operate REST API
- Check for completed user tasks and process accordingly
Advantages:
- Simple to implement
- No additional infrastructure needed
Disadvantages:
- Not real-time (depends on polling interval)
- Increased load on Camunda APIs
- Less efficient
Recommendation
The Kafka connector approach is indeed the cleanest and most scalable solution, especially if you:
- Need real-time notifications
- Want to decouple your systems
- Plan to scale your architecture
- Already have or can set up Kafka infrastructure
For your .NET application, you can use Kafka client libraries like Confluent.Kafka to consume the messages.
Implementation Pattern
Here’s how your BPMN would look:
[User Task: Approval] → [Service Task: Kafka Notification] → [Next Step...]
The service task would use the Kafka connector to publish an event like:
{
"taskId": "task-123",
"processInstanceId": "process-456",
"approvalStatus": "approved",
"approver": "john.doe",
"timestamp": "2024-01-15T10:30:00Z"
}
References:
Would you like me to help you with the specific configuration of the Kafka connector or discuss any other aspects of this integration?