SimpleRelayPool

SimpleRelayPool

The SimpleRelayPool is the default implementation of the RelayHandler interface provided by the @contextvm/sdk. It uses the SimplePool from the nostr-tools library to manage connections to a list of specified relays.

Overview

The SimpleRelayPool provides a straightforward way to manage relay connections for most common use cases. Its responsibilities include:

• Connecting to a predefined list of Nostr relays.
• Publishing events to all relays in the pool.
• Subscribing to events from all relays in the pool.
• Managing the lifecycle of connections and subscriptions.

It is a simple but effective solution for applications that need to interact with a static set of relays.

constructor(relayUrls: string[])

The constructor takes a single argument:

• relayUrls: An array of strings, where each string is the URL of a Nostr relay (e.g., wss://relay.damus.io).

Usage Example

import { SimpleRelayPool } from "@contextvm/sdk";
import { NostrClientTransport } from "@contextvm/sdk";

// 1. Define the list of relays you want to connect to
const myRelays = [
  "wss://relay.damus.io",
  "wss://relay.primal.net",
  "wss://nos.lol",
];

// 2. Create an instance of the SimpleRelayPool
const relayPool = new SimpleRelayPool(myRelays);

// 3. Pass the instance to a transport
const transport = new NostrClientTransport({
  relayHandler: relayPool,
  // ... other options
});

How It Works

The SimpleRelayPool wraps the SimplePool from nostr-tools and implements the methods of the RelayHandler interface:

• connect(): Iterates through the provided relayUrls and calls pool.ensureRelay() for each one, which establishes a connection if one doesn’t already exist.
• disconnect(): Closes the connections to the specified relays.
• publish(event): Publishes the given event to all relays in the pool by calling pool.publish().
• subscribe(filters, onEvent): Creates a subscription on all relays in the pool using pool.subscribeMany(). It tracks all active subscriptions so they can be closed later.
• unsubscribe(): Closes all active subscriptions that were created through the subscribe method.

Limitations

The SimpleRelayPool is designed for simplicity. It connects to all provided relays and does not include advanced features.

For applications that require more sophisticated relay management, you may want to create a Custom Relay Handler.

Next Steps

• Learn how to build a custom relay handler: Custom Relay Handler