websocket - 如何在suave中通过websocket实现服务器推送？

Question

我可以写这样的东西吗

let echo (ws: WebSocket) =
    fun ctx -> socket {
        let loop = ref true            
        while !loop do
            let! message = Async.Choose (ws.read()) (inbox.Receive())
            match message with
            | Choice1Of2 (wsMessage) ->
                match wsMessage with
                | Ping, _, _ -> do! ws.send Pong [||] true
                | _ -> ()
            | Choice2Of2 pushMessage -> do! ws.send Text pushMessage true
    }

还是需要2个单独的套接字循环来进行并发读写？

Answer 1

我认为您可以使用Async.Choose解决此问题(有很多实现-尽管我不确定最规范的实现在哪里)。

也就是说，您当然可以创建两个循环-在socket { .. }中读取一个循环，以便您可以从Web套接字接收数据。写一个可以是普通的async { ... }块。

这样的事情应该可以解决问题:

let echo (ws: WebSocket) =  
    // Loop that waits for the agent and writes to web socket
    let notifyLoop = async { 
      while true do 
        let! msg = inbox.Receive()
        do! ws.send Text msg }

    // Start this using cancellation token, so that you can stop it later
    let cts = new CancellationTokenSource()
    Async.Start(notifyLoop, cts.Token)

    // The loop that reads data from the web socket
    fun ctx -> socket {
        let loop = ref true            
        while !loop do
            let! message = ws.read()
            match message with
            | Ping, _, _ -> do! ws.send Pong [||] true
            | _ -> () }