Channels Overview

This page covers TypeScript-specific channel details. For the general concept of what a channel is, see Channels.

Built-in channels

MessagePortChannel Web Workers, Node.js worker_threads, and MessageChannel communication.

HTTPChannel HTTP-based communication with NDJSON streaming for REST APIs and edge functions.

MCPChannel Model Context Protocol integration — expose commands as AI agent tools or consume remote MCP servers.

The ICommandChannel interface

All channels implement ICommandChannel. Create custom transports (WebSocket, gRPC, etc.) by implementing this interface:

interface ICommandChannel {
  readonly id: string
  start(): Promise<void>
  close(): Promise<void>
  sendMessage(message: unknown): void
  on(event: 'message', listener: (message: unknown) => void): void
  on(event: 'close', listener: () => void): void
}

Method	Description
id	Unique identifier for this channel
start()	Initialize the channel (called automatically by the registry)
close()	Close the channel and clean up resources
sendMessage()	Send a message through the channel
on('message')	Subscribe to incoming messages
on('close')	Subscribe to channel close events

Tip

Messages must follow the Protocol format. The registry handles correlation via id / thid — your channel just serializes and transports the messages.

Registering channels

const channel = new MessagePortChannel('worker', workerPort)
await registry.registerChannel(channel)