Can I Use WebSocket with Grapevine?

[scottoffen]

User @seikosantana asked about WebSocket support in Grapevine 5.

The short answer is I think so. I'm not well versed on WebSocket, so there might be a better way to implement this, but here is the approach from what I understand about WebSocket.

In your route, you will need to cast the IHttpContext argument to the concrete class HttpContext, and you will find on that class the Advanced property. This property is the underlying HttpListenerContext for this request, which means you can access the AcceptWebSocketAsync method.

[RestRoute("Get", "/path", Name = "Web Socket Example", Description = "Sample route for WebSocket")]
public async Task WebSocketHandler(IHttpContext context)
{
    if (context is HttpContext ctx)
    {
        if (ctx.Advanced.Request.IsWebSocketRequest)
        {
            var webSocketContext = await ctx.Advanced.AcceptWebSocketAsync("");
            // do your stuff here, I guess?
        }
    }

    await context.Response.SendResponseAsync(HttpStatusCode.Ok);
}

I'm open to suggestions on how to improve the experience here, but unless I can get some rather quick and concrete feedback, this is how it will be for the v5 release.

[seikosantana]

Hi,

Thank you for your response.
I havent checked github for a while. That snippet seems cool. I will try that out.

[scottoffen]

I haven't actually tested it yet, I've been on the road the past week. It might need some changes.

[seikosantana]

I have started to work on the websocket part with Grapevine and empty string can't be used as subprotocol. And I have not yet succeeded attempting connection from Postman

[seikosantana]

So some notes is i shouldn't be sending responses with the HttpContext or else the socket will close.
Seems like by default if no response is sent from a route, it sents a 500 Unimplemented and that causes the socket to on the client.

So for now I have to make it doesn't leave the route action method so it doesn't sent a respond at the end of route invocation.

That doesn't seem to be much problem

[scottoffen]

There is a work around to that. Set the RequireRouteResponse property to false in your startup class.

public void ConfigureServer(IRestServer server)
{
    server.Router.Options.RequireRouteResponse = false;
}

If not response is sent, the router and server will not see this as an error condition.