# node-walve

**walve** is a stream based WebSocket implementation for node.js.

    const walve = require('walve');

    walve.createServer(wsocket => {
      wsocket.on('incoming', incoming => {
        // handle readable incoming stream
      })
    }).listen(server)

## Examples

You can find working examples in the `/opt` directory of this project.

- **echo**: echos messages back to the browser
- **sugar**: extends `Server` with some api sugar
- **stream**: streams file through websocket to document
- **cluster**: streams file through websocket cluster (hot concurrency)

Furthermore there are currently two real world examples using walve.
Feel free to add own projects:

- [nearby](https://github.com/bodokaiser/nearby) real time geolocation
  tracking with walve and google maps
- [messenger](https://github.com/bodokaiser/messenger) real time
  messenger with support for image streaming

## Installation

The package is available on **npm** as **walve**.

    npm install --save walve

## Documentation

### Server

#### new Server([options])

Creates a new `Server` instance. Valid `options` are for example `url`
which can be used to have multiple websocket servers on one http server.

#### Event: "connect"

Emitted when a new WebSocket upgrade was established. Provides instance
of `Socket` as argument.

#### Event: "error"

Emitted when an error occurs. For example on failed upgrade.

#### server.listen(http)

Listens on the "upgrade" event of the `http` instance.

### Socket

Abstracts a single WebSocket connection.

#### new Socket(socket)

Creates a new duplex stream `Socket` which reads and writes from the
underlaying TCP socket.

#### Event: "incoming"

    wsocket.on('incoming', function(incoming) {
      incoming.pipe(process.stdout, { end: false });
    });

Emitted when a WebSocket frame is received. First argument is a an
instance of `Incoming`.

#### Event: "end"

Emitted when the TCP connection closes.

#### socket.end

    wsocket.end();
    // actually better:
    var outgoing = new Outgoing({ opcode: 0x08 });
    outgoing.pipe(socket);
    outgoing.end();

Will completly close the TCP socket.

### Incoming

Abstracts an incoming WebSocket frame.

#### new Incoming()

Creates a new instance of the `Incoming` transform stream. Which
transforms incoming WebSocket frames to node buffers.

#### incoming.header

    if (incoming.header.opcode === 0x01) {
        // handle data as unicode
    }

Contains `fin`, `opcode`, `length` and so on. You will mainly
be interested in `header.opcode` as the other values are more for
internal use.

#### Event: "readable"

    var message = '';

    incoming.on('readable', function() {
      message += incoming.read().toString();
    });

Emitted when there is payload to read from the frame.

#### Event: "end"

    incoming.on('end', function() {
      // log prev buffered messages
      console.log(message);
    });

Emitted when frame ends **and** data was consumed with
`incoming.read()`.

### Outgoing

Abstracts an outgoing WebSocket frame.

#### new Outgoing([options])

Returns a new instance of `Outgoing` transform stream. As this is a
transform and not a writable stream you must pipe `outgoing` to the
websocket `socket` provided by the server "connect" event. Options
can contain a `header` object. See below for more.

#### outgoing.header

    outgoing.header.final = true;
    outgoing.header.masked = false;
    outgoing.header.opcode = 0x01;
    outgoing.header.length = 0x0a;

    outgoing.write('Hello World').pipe(wsocket, { end: false });

Sets the header information of an outgoing frame. You can omit `final`
and `opcode` as they will use most common default values `true` and
`0x01` (text frame).