Event Bus

The event bus is the backbone of PLATFORMA's inter-service communication. All state changes are published as events, enabling loose coupling between services and supporting async workflows.

Architecture

PLATFORMA uses NATS JetStream as the event bus, providing:

• At-least-once delivery — Events are persisted and redelivered on failure
• Consumer groups — Multiple instances of a service share the workload
• Replay — Historical events can be replayed for recovery or debugging
• Filtering — Consumers subscribe to specific event patterns

Event Structure

All events follow a consistent envelope format:

{
  "id": "evt_abc123",
  "type": "order.provisioned",
  "version": "1.0",
  "tenant_id": "ten_xyz789",
  "timestamp": "2026-03-15T10:05:22Z",
  "source": "provisioning-service",
  "data": {
    "order_id": "ord_xyz789",
    "resources": [
      { "id": "res_vm_001", "type": "virtual_machine", "status": "running" }
    ]
  },
  "metadata": {
    "correlation_id": "req_abc123",
    "trace_id": "trace_def456"
  }
}

Event Categories

Order Events

Resource Events

Billing Events

Consumer Patterns

Direct Processing

A service directly processes events to update its own state:

order.created → Billing Service → Create subscription record

Event Choreography

Multiple services react to the same event independently:

order.provisioned → Billing Service  → Activate subscription
                  → Notification Svc → Send welcome email
                  → Monitoring Svc   → Configure alerts

Saga Pattern

Long-running workflows coordinate across services:

order.created → Provisioning → resource.created → DNS Setup → dns.configured → Monitoring → order.provisioned

If any step fails, compensating events undo previous steps.