Events API

API for event-based pipeline execution.

Overview

Through the Events API, you can execute pipelines using events from Kafka topics as triggers. Serverless event processing is performed based on Knative Eventing.

Prerequisites

• The pipeline must have a Kafka topic specified in the event option.
• Knative Eventing and Kafka source must be installed in the cluster.

Endpoints

POST /api/v1/events/{pipeline_id}

Starts the event trigger for a pipeline.

Path Parameters

Parameter	Type	Required	Description
pipeline_id	string	Yes	Pipeline ID

Query Parameters

Parameter	Type	Required	Description
pipeline_version	string	No	Use specific version

Response

200 OK

{
  "message": "Event started successfully"
}

Behavior Description

1. Deletes existing Knative service and source if present.
2. Creates a new Knative service.
3. Creates a Kafka source to subscribe to the specified topic.
4. When a message arrives at the topic, the pipeline is executed.

Error Responses

Status Code	Description
500 Internal Server Error	Pipeline does not have event option

---

GET /api/v1/events/{pipeline_id}

Retrieves the status of an event trigger.

Path Parameters

Parameter	Type	Required	Description
pipeline_id	string	Yes	Pipeline ID

Response

200 OK

{
  "ready": true
}

Field	Type	Description
ready	boolean	Knative service ready status

---

DELETE /api/v1/events/{pipeline_id}

Stops and deletes the event trigger.

Path Parameters

Parameter	Type	Required	Description
pipeline_id	string	Yes	Pipeline ID

Response

200 OK

{
  "message": "Event deleted successfully"
}

Pipeline Configuration

To use event triggers, you must specify a Kafka topic in the pipeline options.

{
  "id": "pipeline-abc123",
  "name": "Event Pipeline",
  "options": {
    "event": "my-kafka-topic"
  },
  "steps": [...]
}

Architecture

┌──────────────┐     ┌─────────────────┐     ┌──────────────────┐
│ Kafka Topic  │────>│ Knative Source  │────>│ Knative Service  │
│ (event)      │     │ (KafkaSource)   │     │ (Pipeline Runner)│
└──────────────┘     └─────────────────┘     └──────────────────┘

1. Kafka Topic: Topic where event messages are published
2. Knative Source: Subscribes to Kafka topic and delivers events
3. Knative Service: Receives events and executes pipeline

Usage Examples

cURL

# Start event trigger
curl -X POST https://api.dhub.io/api/v1/events/pipeline-abc123 \
  -H "Authorization: Bearer <access_token>"

# Get event status
curl https://api.dhub.io/api/v1/events/pipeline-abc123 \
  -H "Authorization: Bearer <access_token>"

# Stop event trigger
curl -X DELETE https://api.dhub.io/api/v1/events/pipeline-abc123 \
  -H "Authorization: Bearer <access_token>"

Event-Based Pipeline Workflow

// 1. Create pipeline (including event option)
await fetch('/api/v1/pipelines/', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${token}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'Order Processing',
    options: {
      event: 'orders-topic'
    },
    steps: [...]
  })
});

// 2. Start event trigger
await fetch(`/api/v1/events/${pipelineId}`, {
  method: 'POST',
  headers: { 'Authorization': `Bearer ${token}` }
});

// 3. Check status
const status = await fetch(`/api/v1/events/${pipelineId}`, {
  headers: { 'Authorization': `Bearer ${token}` }
}).then(res => res.json());

console.log('Event ready:', status.ready);

Scaling

Knative automatically scales based on traffic:

• Scale to Zero: Instances scale down to 0 when there are no events
• Auto-scaling: Automatic scaling based on event processing volume