Pub/Sub (Publish-Subscribe)

Pub/Sub is a messaging pattern enabling asynchronous communication between components through topics, allowing publishers and subscribers to operate independently.

Architecture

Publishers               Topic/Broker            Subscribers
┌──────────┐            ┌──────────┐           ┌──────────┐
│ Service A│───────────►│  Topic:  │──────────►│ Service B│
└──────────┘            │  events  │           └──────────┘
┌──────────┐            │          │           ┌──────────┐
│ Service C│───────────►│          │──────────►│ Service D│
└──────────┘            └──────────┘           └──────────┘

Example

// Publisher
await pubsub.publish('entity-created', {
  entityId: 'person_123',
  type: 'Person',
  properties: {name: 'Jane'}
});

// Subscriber
pubsub.subscribe('entity-created', async (message) => {
  console.log('New entity:', message.entityId);
  // Update search index, send notification, etc.
});

TrustGraph Events

// TrustGraph uses Apache Pulsar for pub/sub
await trustgraph.events.subscribe('graph.node.created', async (event) => {
  // React to new nodes
  console.log('Node created:', event.nodeId);
});

await trustgraph.events.subscribe('graph.relationship.created', async (event) => {
  // React to new relationships
  console.log('Relationship created:', event.relationshipType);
});

Benefits

• Decoupling: Publishers don't know subscribers
• Scalability: Add subscribers without changing publishers
• Asynchronous: Non-blocking communication
• Fan-out: One message, many subscribers

See Also

• Containers
• Multi-Tenant