[yasserf]

I have been working on an idea/Node.js library called vramework.dev recently, and a big part of it focuses on addressing the main complexities mentioned below.

For a bit of background, in order to tackle scalability, the initial approach was to explore serverless architecture. While there are both advantages and disadvantages to serverless, a notable issue with WebSockets on AWS* is that every time a message is received, it invokes a function. Similarly, sending a message to a WebSocket requires invoking an HTTP call to their gateway with the websocket / channel id.

The upside of this approach is that you get out-of-the-box scalability by dividing your code into functions and building things in a distributed fashion. The downside is latency, due to all the extra network hops.

This is where vramework comes in. It allows you to define a few functions (e.g., onConnect, onDisconnect, onCertainMessage) and provides the flexibility to run them locally using libraries like uws, ws, or socket.io, or deploy them in the cloud via AWS or Cloudflare (currently supported).

When running locally, the event bus operates locally as well, eliminating latency issues. If you apply the same framework to serverless, latency increases, but you gain scalability for free.

Additionally, vramework provides the following features:

- Standard Tooling

Each message is validated against its typescript signature at runtime. Any errors are caught and sent to the client. (Note: The error-handling mechanism has not yet been given much thought into as an API). Rate limiting is also incorporated as part of the permissioning system (each message can have permissions checked, one of them could rate limiting)

- Per-Message Authentication

It guards against abuse by ensuring that each message is valid for the user before processing it. For example, you can configure the framework to allow unauthenticated messages for certain actions like authentication or ping/pong, while requiring authentication for others.

- User Sessions

Another key feature is the ability to associate each message with a user session. This is essential not only for authentication but also for the actual functionality of the application. This is done by doing a call to a cache (optionally) which returns the user session associated with the websocket. This session can be updated during the websocket lifetime if needed (if your protocol deals with auth as part of it's messages and not on connection)

Some doc links:

https://vramework.dev/docs/channels/channel-intro

A post that explains vramework.dev a bit more in depth (linked directly to a code example for websockets):

https://presentation.vramework.dev/#/33/0/5

And one last thing, it also produces a fully typed websocket client, so if using routes (where a property in your message indicates which function to use, the approach AWS uses serverless).

Would love to get thoughts and feedback on this!

edit: *and potentially Cloudflare, though I’m not entirely sure of its internal workings, just the Hibernation server and optimising for cost saving

[yasserf]

  const onConnect: ChannelConnection<'hello!'> = async (services, channel) => {
    // On connection (like onOpen)
    channel.send('hello') // This is checked against the input type
  }

  const onDisconnect: ChannelDisconnection = async (services, channel) => {
    // On close
    // This can't send anything since channel closed
  }

  const onMessage: ChannelMessage<'hello!' | { name: string }, 'hey'> = async (services, channel) => {
    channel.send('hey')
  }

  export const subscribeToLikes: ChannelMessage<
    { talkId: string; action: 'subscribeToLikes' },
    { action: string; likes: number }
  > = async (services, channel, { action, talkId }) => {
    const channelName = services.talks.getChannelName(talkId)
    // This is a service that implements a pubsub/eventhub interface
    await services.eventHub.subscribe(channelName, channel.channelId)
    // we return the action since the frontend can use it to route to specific listeners as well (this could be absorbed by vrameworks runtime in future)
    return { action, likes: await services.talks.getLikes(talkId) }
  }

  addChannel({
    name: 'talks',
    route: '/',
    auth: true,
    onConnect,
    onDisconnect,
    // Default message handler
    onMessage,
    // This will route the message to the correct function if a property action exists with the value subscribeToLikes (or otherwise)
    onMessageRoute: {
      action: {
        subscribeToLikes: {
          func: subscribeToLikes,
          permissions: {
            isTalkMember: [isTalkMember, isNotPresenter],
            isAdmin
          },
        },
      },
    },
  })

A code example.

Worth noting you can share functions across websockets as well, which allows you to compose logic across different ones if needed