Events API

API for event-driven pipeline execution.

Overview

The Events API allows you to trigger pipeline executions based on events from message topics. It uses serverless event processing for automatic scaling.

Prerequisites

• A message topic must be specified in the pipeline's event option.
• The event processing service 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 a specific version

Response

200 OK

{
  "message": "Event started successfully"
}

Behavior Description

1. If existing event services and sources exist, they are deleted.
2. A new event service is created.
3. A message source is created to subscribe to the specified topic.
4. When a message arrives on the topic, the pipeline is executed.

Error Responses

Status Code	Description
500 Internal Server Error	Pipeline does not have an 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	Event service readiness 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, a message topic must be specified in the pipeline options.

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

Architecture

┌──────────────┐     ┌─────────────────┐     ┌──────────────────┐
│ Message Topic│────>│ Event Source    │────>│ Event Service    │
│ (event)      │     │ (Subscriber)    │     │ (Pipeline Runner)│
└──────────────┘     └─────────────────┘     └──────────────────┘

1. Message Topic: The topic where event messages are published
2. Event Source: Subscribes to the topic and delivers events
3. Event Service: Receives events and executes the pipeline

Usage Examples

cURL

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

# Check 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-Driven Pipeline Workflow

// 1. Create pipeline (with 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

The event processing service automatically scales based on traffic:

• Scale to Zero: When there are no events, instances scale down to 0
• Auto-scaling: Automatically scales out based on event processing volume