@push.rocks/isotransport is a tiny TypeScript transport layer for bi-directional, best-effort messaging over WebSockets. It gives Node.js and browser code the same simple connection API while keeping the actual transport intentionally lean: open a connection, send string, ArrayBuffer, or Uint8Array payloads, react to messages, and close cleanly.

Issue Reporting and Security

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Install

pnpm add @push.rocks/isotransport

What It Does

isotransport wraps WebSocket communication in three exported building blocks:

IsotransportServer: starts a WebSocket server in Node.js and emits typed connection objects.
IsotransportClient: connects to a WebSocket URL from Node.js or a browser-like runtime.
IsotransportConnection: represents one open peer connection and provides send(), close(), and typed event listeners.

The module is deliberately best-effort. It does not queue messages, retry delivery, persist data, or add protocol framing. If the socket is closed, send() throws. This makes the library useful as a clean transport primitive that can sit below your own application protocol.

Quick Start

import {
  IsotransportClient,
  IsotransportServer,
  type TIsotransportMessage,
} from '@push.rocks/isotransport';

const server = new IsotransportServer({
  port: 8080,
  host: '127.0.0.1',
});

server.on('connection', (connection) => {
  console.log(`client connected: ${connection.id}`);

  connection.on('message', (message: TIsotransportMessage) => {
    console.log('server received:', message);
    connection.send('pong');
  });

  connection.on('close', () => {
    console.log(`client disconnected: ${connection.id}`);
  });
});

await server.listen();

const client = new IsotransportClient({
  url: 'ws://127.0.0.1:8080',
});

client.on('message', (message) => {
  console.log('client received:', message);
});

await client.connect();
client.send('ping');

// Later, during shutdown:
client.close();
await server.close();

Server API

Create a server with a port and optional host/path:

const server = new IsotransportServer({
  port: 3000,
  host: '127.0.0.1',
  path: '/transport',
});

await server.listen();

IsotransportServer events:

connection: emitted with an IsotransportConnection for every accepted WebSocket client.
close: emitted after server.close() finishes.
error: emitted when the underlying WebSocket server reports an error.

Server instances expose a connections set, so you can inspect or close currently connected peers:

for (const connection of server.connections) {
  connection.send('server is shutting down');
}

await server.close();

Client API

Create a client with a WebSocket URL and optional protocols:

const client = new IsotransportClient({
  url: 'ws://127.0.0.1:3000/transport',
  protocols: ['my-protocol'],
});

await client.connect();
client.send('hello');

IsotransportClient events:

open: emitted with the active IsotransportConnection after the socket opens.
message: emitted for every received message.
close: emitted when the socket closes.
error: emitted when the socket reports an error.

In browsers, IsotransportClient uses globalThis.WebSocket. In Node.js, it falls back to the package's ws dependency.

Connection API

Every connection supports:

connection.on('message', (message) => {});
connection.on('close', () => {});
connection.on('error', (error) => {});

connection.send('text payload');
connection.send(new Uint8Array([1, 2, 3]));
connection.close();

connection.on(...) returns an unsubscribe function:

const stopListening = connection.on('message', (message) => {
  console.log(message);
});

stopListening();

Supported payloads are represented by TIsotransportMessage:

type TIsotransportMessage = string | ArrayBuffer | Uint8Array;

Text frames are delivered as strings. Binary frames are delivered as binary data from the underlying WebSocket implementation.

Practical Notes

Call await server.listen() before connecting clients.
Call await client.connect() before sending from the client.
send() throws if the connection is not open.
server.close() closes all tracked connections and stops the WebSocket server.
The library does not serialize objects; serialize JSON yourself if your protocol needs structured data.
The library does not provide authentication, authorization, heartbeats, retries, or message acknowledgements.

JSON Messages

connection.send(JSON.stringify({
  type: 'user.joined',
  payload: {
    userId: 'user-123',
  },
}));

connection.on('message', (message) => {
  if (typeof message !== 'string') {
    return;
  }

  const parsed = JSON.parse(message) as {
    type: string;
    payload: unknown;
  };

  console.log(parsed.type, parsed.payload);
});

Binary Messages

const bytes = new Uint8Array([1, 2, 3, 4]);
client.send(bytes);

client.on('message', (message) => {
  if (message instanceof Uint8Array) {
    console.log('received bytes:', message.byteLength);
  }
});

Development

pnpm install
pnpm test
pnpm build

Tests are written with @git.zone/tstest and exercise a real server/client message exchange over WebSockets.

License and Legal Information

This repository contains open-source code licensed under the MIT License. A copy of the license can be found in the LICENSE file.

Please note: The MIT License does not grant permission to use the trade names, trademarks, service marks, or product names of the project, except as required for reasonable and customary use in describing the origin of the work and reproducing the content of the NOTICE file.

Trademarks

This project is owned and maintained by Task Venture Capital GmbH. The names and logos associated with Task Venture Capital GmbH and any related products or services are trademarks of Task Venture Capital GmbH or third parties, and are not included within the scope of the MIT license granted herein.

Use of these trademarks must comply with Task Venture Capital GmbH's Trademark Guidelines or the guidelines of the respective third-party owners, and any usage must be approved in writing. Third-party trademarks used herein are the property of their respective owners and used only in a descriptive manner, e.g. for an implementation of an API or similar.

readme.md

@push.rocks/isotransport