No documentation or examples for sending websocket messages

[danellis]

I'd like to be able to start sending messages on a websocket as soon as it's opened (i.e. not in response to incoming messages). I don't see anything in the documentation or examples that shows how this would be done.

[gregor-rayman]

Here a small sample of a web socket chat app.

Here it start sending right after the connection is established:

          case HandshakeComplete =>
            ...
              ch.writeAndFlush(WebSocketFrame.text(s"Hello $name")) *>

Here the whole chat app:

import zio.*
import zio.Console.printLine
import zhttp.http.*
import zhttp.service.*
import zhttp.service.ChannelEvent.UserEvent.{ HandshakeComplete, HandshakeTimeout }
import zhttp.service.ChannelEvent.{ ChannelRead, ChannelUnregistered, UserEventTriggered }
import zhttp.socket.*
import zio.*
import zio.stream.ZStream

object WebSocketEcho extends ZIOAppDefault {

  private val portConfig = System.env("port").map(_.flatMap(_.toIntOption).getOrElse(9009))

  private def chat(socketsRef: Ref[Map[String, Channel[WebSocketFrame]]], name: String) =
    def broadcast(from: Channel[WebSocketFrame], msg: String) =
      for
        sockets <- socketsRef.get
        _       <- ZIO.foreachParDiscard(sockets.filterNot(_._1 == from.id).values) { c =>
                     c.writeAndFlush(WebSocketFrame.text(msg))
                   }
      yield ()

    Http.collectZIO[WebSocketChannelEvent] {
      case ChannelEvent(ch, UserEventTriggered(event))             =>
        event match
          case HandshakeTimeout  =>
            ZIO.logInfo("Connection failed!")
          case HandshakeComplete =>
            broadcast(ch, s"$name joined") *>
              ch.writeAndFlush(WebSocketFrame.text(s"Hello $name")) *>
              socketsRef.update(ss => ss + (ch.id -> ch))
      case ChannelEvent(ch, ChannelRead(WebSocketFrame.Text(msg))) =>
        broadcast(ch, s"$name says: $msg")
      case ChannelEvent(ch, ChannelUnregistered)                   =>
        socketsRef.update(ss => ss - ch.id) *>
          broadcast(ch, s"$name left")
    }

  private def chatRoom(socketsRef: Ref[Map[String, Channel[WebSocketFrame]]]): Http[Any, Nothing, Request, Response] =
    Http.collectZIO[Request] { case Method.GET -> !! / "chat" / name =>
      chat(socketsRef, name).toSocketApp.toResponse
    }

  override val run: ZIO[Any, Throwable, ExitCode] = for
    port       <- portConfig
    _          <- Console.printLine(s"Starting server on http://localhost:$port")
    socketsRef <- Ref.make(Map[String, Channel[WebSocketFrame]]())
    _          <- Server.start(port, chatRoom(socketsRef))
  yield ExitCode.success

}

[jdegoes]

/bounty $125

For a number of examples, documented and written according to best-practices.

[algora-pbc]

💎 $125 bounty created by ZIO
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Attempt	Started (GMT+0)	Solution
🟢 @JatinSharma32		#2134
🟢 @987Nabil		#2567

[JatinSharma32]

Working on it...

[algora-pbc]

💡 JatinSharma32 submitted a pull request that claims the bounty. You can visit your org dashboard to reward.
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[JatinSharma32]

I have submitted a pull request #2134 . Could you please review it?
In the meantime, would it be possible to assign me to this issue?

[algora-pbc]

💡 @987Nabil submitted a pull request that claims the bounty. You can visit your bounty board to reward.

[algora-pbc]

🎉🎈 @987Nabil has been awarded $125! 🎈🎊