Replace SocketAdapter with Transports

[douglascayers]

Background

A variation of #1042 based on the comment thread there about extending the factory function concept further to abstract the Ros class from socket implementations.

Changes

• Replaces SocketAdapter with Transport, which provide an abstraction over socket implementations (native WebSocket, ws npm module, socket.io, RTC, etc).
• Removed RTC web socket implementation. Users who need it can provide their own TransportFactory modeled after the WebSocketTransportFactory.
• Errors when handling socket messages to be parsed into RosbridgeMessage are now emitted by the transport rather than console logged or swallowed. Gives calling code an easier programmatic option to be notified of these issues.
• Updated type definitions for a few utilities.
• Add and update tests.
• Changed event connection to open to be consistent with the underlying socket event type.
• Ros emits the open, close, and error events as pass-throughs of whatever value the transport emitted (e.g. string, Error, Event, etc)

Example Usage

// -- Example 1 -- //

// Defaults to WebSocket transports
// Uses native WebSocket if available, else the "ws" node module
const ros = new Ros();

// -- Example 2 -- //

// Customize the WebSocket implementation
// This example specifies the handshake timeout
const ros = new Ros({
  transportFactory: async (url: string): ITransport => {
    const socket = new ws.WebSocket(url, {
      handshakeTimeout: 30_000,
    });
    socket.binaryType = "arraybuffer";
    return new WsWebSocketTransport(socket);
  },
});

// -- Example 3 -- //

// Bring your own transport with full control
// over encoding/decoding messages
const MyCustomTransport extends EventEmitter implements ITransport {
  constructor(url: string) {
    // connect to the url however you wish
    // when receive messages from the server,
    // broadcast them via `this.emit("message", ...)`
  }

  send(message: RosbridgeMessage): void {
    // roslib wants to send a message to the server
    // serialize and send the message however you wish
  }

  close(): void {
    // disconnect from the server
  }

  // lifecycle methods to mirror WebSocket spec
  isConnecting(): boolean { ... }
  isOpen(): boolean { ... }
  isClosing(): boolean { ... }
  isClosed(): boolean { ... }
}

const ros = new Ros({
  transportFactory: async (url: string): ITransport => {
    return new MyCustomTransport(url);
  },
});

[EzraBrooks]

Looks great, just some nits

[EzraBrooks]

btw I'm planning on really highlighting this feature in the 2.0 release notes because it's cool and it will help anyone who was relying on the almost-certainly-unmaintained NodeTCP and RTC transports :)

[EzraBrooks]

Since this is nearly there, I'm gonna poke at it, if you don't mind. really trying to get 2.0 out the door before I get busy at my new job 😆

[EzraBrooks]

oop, except this PR doesn't have "allow changes from maintainers" enabled

[EzraBrooks]

Here's a proposed change to allow fully lazy-loading ws. With this, once the tests are adjusted to pass, I think we're good to merge.

0001-Move-WsWebSocketTransport-to-lazy-loaded-file.patch

[douglascayers]

oop, except this PR doesn't have "allow changes from maintainers" enabled

Sorry about that! I don't even see where I can enable it =/

I'll work on getting the patch applied. Confused why the tests are failing, they all pass locally 🤔

[EzraBrooks]

Yeah I think it defaults to being turned off when the source branch is from an organization

[EzraBrooks]

Confused why the tests are failing, they all pass locally

probably need to reinstall deps, since I changed the underlying PNG package

[douglascayers]

Confused why the tests are failing, they all pass locally

probably need to reinstall deps, since I changed the underlying PNG package

Yep, thanks, I'm reworking the tests that were mocking pngparse

[douglascayers]

Changes pushed, ready for CI to run 😎

[douglascayers]

[Vitest] Unexpected .only modifier.

doh, removing that...

[EzraBrooks]

LGTM. will re-run that flaked test. need to figure out what the deal with that is.. it happens like 1% of the time

[EzraBrooks]

thanks so much for the contribution and sorry for the back-and-forth!

[douglascayers]

Woo hoo! Happy to have contributed, thanks for shepherding this project forward 👏