> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# PubSub

> Publish-subscribe messaging

Agents can use publish-subscribe messaging to communicate with each other and external systems.

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph LR
    Agent[Agent] --> PubSub[PubSub]
    PubSub --> Subscribers([Subscribers])

    classDef agent fill:#8B0000,stroke:#7C90A0,color:#fff
    classDef tool fill:#189AB4,stroke:#7C90A0,color:#fff

    class Agent agent
    class PubSub,Subscribers tool
    classDef agent fill:#8B0000,color:#fff
    classDef tool fill:#189AB4,color:#fff
```

## Quick Start

<Steps>
  <Step title="Simple Usage">
    ```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    import { createPubSub } from 'praisonai';

    const pubsub = createPubSub();

    // Subscribe to topic
    pubsub.subscribe('orders', (event) => {
      console.log('New order:', event.data);
    });

    // Publish message
    pubsub.publish('orders', { id: '123', total: 99.99 });
    ```
  </Step>

  <Step title="With Configuration">
    ```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    const agent1 = new Agent({
      pubsub,
      onComplete: (result) => {
        pubsub.publish('task.done', result);
      }
    });

    pubsub.subscribe('task.done', (event) => {
      agent2.chat(`Process: ${event.data}`);
    });
    ```
  </Step>
</Steps>

***

## User Interaction Flow

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
    participant Agent1
    participant PubSub
    participant Agent2
    
    Agent1->>PubSub: publish('task.done', data)
    PubSub->>Agent2: Notify subscriber
    Agent2->>Agent2: Process event
```

***

## Configuration Levels

```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
// Level 1: Function - Simple create
const pubsub = createPubSub();

// Level 2: Dict - With options
const pubsub = createPubSub({
  maxListeners: 100,
  wildcard: true
});

// Level 3: Instance - Full control
import { EventEmitterPubSub } from 'praisonai';

const pubsub = new EventEmitterPubSub({
  maxListeners: 100,
  wildcard: true,
  delimiter: '.',
  onError: (err) => console.error(err)
});
```

***

## Use Cases

| Pattern      | Description                      |
| ------------ | -------------------------------- |
| Events       | Notify when things happen        |
| Decoupling   | Components don't know each other |
| Broadcasting | Send to multiple listeners       |
| Queuing      | Process messages asynchronously  |

***

## API Reference

<Card title="EventEmitterPubSub" icon="code" href="/docs/sdk/reference/typescript/classes/EventEmitterPubSub">
  PubSub implementation
</Card>

***

## Best Practices

<AccordionGroup>
  <Accordion title="Use descriptive topics">
    `user.created` is clearer than `event1`.
  </Accordion>

  <Accordion title="Handle errors">
    Subscribers should handle their own errors.
  </Accordion>

  <Accordion title="Unsubscribe when done">
    Prevent memory leaks by cleaning up.
  </Accordion>
</AccordionGroup>

***

## Related

<CardGroup cols={2}>
  <Card title="Events" icon="bell" href="/docs/js/events">
    Event system
  </Card>

  <Card title="Teams" icon="users" href="/docs/js/teams">
    Multi-agent teams
  </Card>
</CardGroup>