Handling WebSockets without SignalR in ASP.NET 4

<script lang="javascript">
        var ConnectionString = "ws://" + location.host + "/Handler1.ashx";
        //http://localhost:1981/Handler1.ashx
        console.log(ConnectionString);
        let socket = new WebSocket(ConnectionString); //, "protocolOne"

socket.onopen = function(e) {
    document.body.innerHTML +=("[open] Connection established");
    document.body.innerHTML +=("Sending to server");
    socket.send("My name is John");
};

socket.onmessage = function(event) {
    document.body.innerHTML += (`[message] Data received from server: ${event.data}`);
};

socket.onclose = function(event) {
  if (event.wasClean) {
      document.body.innerHTML += (`[close] Connection closed cleanly, code=${event.code} reason=${event.reason}`);
  } else {
    // e.g. server process killed or network down
    // event.code is usually 1006 in this case
      document.body.innerHTML += ('[close] Connection died');
  }
};

socket.onerror = function(error) {
  document.body.innerHTML += (`[error] ${error.message}`);
};
    </script>

var ConnectionString = "ws://" + location.host + "/Handler1.ashx";

//http://localhost:1981/Handler1.ashx

console.log(ConnectionString);

let socket = new WebSocket(ConnectionString); //, "protocolOne"

socket.onopen = function(e) {

document.body.innerHTML +=("[open] Connection established");

document.body.innerHTML +=("Sending to server");

socket.send("My name is John");

};

socket.onmessage = function(event) {

document.body.innerHTML += (`[message] Data received from server: ${event.data}`);

};

socket.onclose = function(event) {

if (event.wasClean) {

document.body.innerHTML += (`[close] Connection closed cleanly, code=${event.code} reason=${event.reason}`);

} else {

// e.g. server process killed or network down

// event.code is usually 1006 in this case

document.body.innerHTML += ('[close] Connection died');

}

};

socket.onerror = function(error) {

document.body.innerHTML += (`[error] ${error.message}`);

};

</script>

Imports System.Net.WebSockets
Imports System.Threading
Imports System.Threading.Tasks
Imports System.Web
Imports System.Web.Services

Public Class Handler1
    Implements System.Web.IHttpHandler

    Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

        'context.Response.ContentType = "text/plain"
        'context.Response.Write("Hello World!")
        If (context.IsWebSocketRequest) Then
            context.AcceptWebSocketRequest(AddressOf HandleWebSocket)

        Else
            context.Response.StatusCode = 400
        End If

    End Sub

    Private Async Function HandleWebSocket(ByVal wsContext As WebSocketContext) As Task
        Const maxMessageSize As Integer = 1024
        Dim receiveBuffer As Byte() = New Byte(1023) {}
        Dim socket As WebSocket = wsContext.WebSocket
        Global_asax.WebSocketsConnected.Add(socket)
        While socket.State = WebSocketState.Open
            Dim receiveResult As WebSocketReceiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer), CancellationToken.None)

            If receiveResult.MessageType = WebSocketMessageType.Close Then
                Await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, CancellationToken.None)
            ElseIf receiveResult.MessageType = WebSocketMessageType.Binary Then
                Await socket.CloseAsync(WebSocketCloseStatus.InvalidMessageType, "Cannot accept binary frame", CancellationToken.None)
            Else
                Dim count As Integer = receiveResult.Count

                While receiveResult.EndOfMessage = False

                    If count >= maxMessageSize Then
                        Dim closeMessage As String = String.Format("Maximum message size: {0} bytes.", maxMessageSize)
                        Await socket.CloseAsync(WebSocketCloseStatus.MessageTooBig, closeMessage, CancellationToken.None)
                        Return
                    End If

                    receiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, count, maxMessageSize - count), CancellationToken.None)
                    count += receiveResult.Count
                End While

                Dim receivedString = Encoding.UTF8.GetString(receiveBuffer, 0, count)
                Dim echoString = "You said " & receivedString
                Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(echoString))
                Await socket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)
            End If
        End While
    End Function

    ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
        Get
            Return False
        End Get
    End Property

End Class

Imports System.Net.WebSockets

Imports System.Threading

Imports System.Threading.Tasks

Imports System.Web

Imports System.Web.Services

Public Class Handler1

Implements System.Web.IHttpHandler

Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

'context.Response.ContentType = "text/plain"

'context.Response.Write("Hello World!")

If (context.IsWebSocketRequest) Then

context.AcceptWebSocketRequest(AddressOf HandleWebSocket)

Else

context.Response.StatusCode = 400

End If

End Sub

Private Async Function HandleWebSocket(ByVal wsContext As WebSocketContext) As Task

Const maxMessageSize As Integer = 1024

Dim receiveBuffer As Byte() = New Byte(1023) {}

Dim socket As WebSocket = wsContext.WebSocket

Global_asax.WebSocketsConnected.Add(socket)

While socket.State = WebSocketState.Open

Dim receiveResult As WebSocketReceiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer), CancellationToken.None)

If receiveResult.MessageType = WebSocketMessageType.Close Then

Await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, CancellationToken.None)

ElseIf receiveResult.MessageType = WebSocketMessageType.Binary Then

Await socket.CloseAsync(WebSocketCloseStatus.InvalidMessageType, "Cannot accept binary frame", CancellationToken.None)

Else

Dim count As Integer = receiveResult.Count

While receiveResult.EndOfMessage = False

If count >= maxMessageSize Then

Dim closeMessage As String = String.Format("Maximum message size: {0} bytes.", maxMessageSize)

Await socket.CloseAsync(WebSocketCloseStatus.MessageTooBig, closeMessage, CancellationToken.None)

Return

End If

receiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, count, maxMessageSize - count), CancellationToken.None)

count += receiveResult.Count

End While

Dim receivedString = Encoding.UTF8.GetString(receiveBuffer, 0, count)

Dim echoString = "You said " & receivedString

Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(echoString))

Await socket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)

End If

End While

End Function

ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable

Get

Return False

End Get

End Property

End Class

Add this line to allow current connections to be accessed.

Imports System.Net.WebSockets
Imports System.Web.Optimization

Public Class Global_asax
    Inherits HttpApplication
    Public Shared WebSocketsConnected As New List(Of WebSocket) '<--Add this
    Sub Application_Start(sender As Object, e As EventArgs)
        ' Fires when the application is started
        RouteConfig.RegisterRoutes(RouteTable.Routes)
        BundleConfig.RegisterBundles(BundleTable.Bundles)
    End Sub
End Class

Imports System.Net.WebSockets

Imports System.Web.Optimization

Public Class Global_asax

Inherits HttpApplication

Public Shared WebSocketsConnected As New List(Of WebSocket) '<--Add this

Sub Application_Start(sender As Object, e As EventArgs)

' Fires when the application is started

RouteConfig.RegisterRoutes(RouteTable.Routes)

BundleConfig.RegisterBundles(BundleTable.Bundles)

End Sub

End Class

Send data from another event to trigger to all connected websockets

Public Class Contact
    Inherits Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        Dim Message As String = "Hello!!"
        Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(Message))
        For Each MySocket As Net.WebSockets.WebSocket In Global_asax.WebSocketsConnected
            If MySocket.State = Net.WebSockets.WebSocketState.Open Then
                MySocket.SendAsync(outputBuffer, Net.WebSockets.WebSocketMessageType.Text, True, Threading.CancellationToken.None)
            End If
        Next
    End Sub
End Class

Public Class Contact

Inherits Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load

Dim Message As String = "Hello!!"

Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(Message))

For Each MySocket As Net.WebSockets.WebSocket In Global_asax.WebSocketsConnected

If MySocket.State = Net.WebSockets.WebSocketState.Open Then

MySocket.SendAsync(outputBuffer, Net.WebSockets.WebSocketMessageType.Text, True, Threading.CancellationToken.None)

End If

End Sub

End Class

One last thing, you may also need to enable websockets if your on an older version of a project. Add or merge these params below into your system.web tag

<httpRuntime executionTimeout="300" targetFramework="4.7.2" />

1	<httpRuntime executionTimeout="300" targetFramework="4.7.2" />

And below is a sample of a test client form to use on Desktop machines to communicate with the server if needed, just update the URL to point to your source.

one thing to note, is when dealing with Websockets in this way you must avoid using .Wait on the main thread to prevent deadlocks. When the function itself is called it will halt on the first await command and never return. I think this is because the report data is being processed through the main message pump of the main thread and gets locked by using the wait() command. Its best to check the status in a loop with application.doevents and add a sleep if needed.

Imports System.Net
Imports System.Net.WebSockets
Imports System.Text
Imports System.Threading

Public Class Form1
    Const maxMessageSize As Integer = 1024
    Dim receiveBuffer As Byte() = New Byte(1023) {}

    Dim MySockets As New List(Of System.Net.WebSockets.ClientWebSocket)
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Dim socket As New System.Net.WebSockets.ClientWebSocket
        MySockets.Add(socket)
        Dim result As Task(Of Boolean) = myTask(socket)

        Exit Sub
        While result.Status <> TaskStatus.RanToCompletion
            Application.DoEvents()
        End While
        Debug.WriteLine(result.Status & " result: " & result.Result) ' "WaitingForActivation"
        Exit Sub
        ThisTest()

        Exit Sub


    End Sub

    Public Async Sub ThisTest()
        Dim ws = New System.Net.WebSockets.ClientWebSocket
        ' optional: ignore certificate errors
        Net.ServicePointManager.ServerCertificateValidationCallback = Function(s, c, h, d) True

        Try
            Await ws.ConnectAsync(New Uri("wss://demo.piesocket.com/v3/channel_1?api_key=oCdCMcMPQpbvNjUIzqtvF1d2X2okWpDQj4AwARJuAgtjhzKxVEjQU6IdCjwm&notify_self"), Nothing)
            If (ws.State = WebSockets.WebSocketState.Open) Then
                Debug.Print("Opened.")
                Await ws.SendAsync(New ArraySegment(Of Byte)(System.Text.Encoding.UTF8.GetBytes("{ ""message"":""hello""}")), WebSockets.WebSocketMessageType.Text, True, Nothing)
                Dim bytes(4096) As Byte
                Dim answ = New ArraySegment(Of Byte)(bytes)
                Await ws.ReceiveAsync(answ, Nothing)
                Debug.Print("answer:" + System.Text.Encoding.UTF8.GetString(answ.Array))
            Else
                Debug.Print("Not opened?!")
            End If
        Catch
            Debug.Print("Error.")
        End Try
    End Sub

    Private Async Function myTask(socket As System.Net.WebSockets.ClientWebSocket) As Task(Of Boolean)
        Dim myToken As New CancellationTokenSource(5000)
        Net.ServicePointManager.ServerCertificateValidationCallback = Function(s, c, h, d) True

        Await socket.ConnectAsync(New Uri("wss://demo.piesocket.com/v3/channel_1?api_key=oCdCMcMPQpbvNjUIzqtvF1d2X2okWpDQj4AwARJuAgtjhzKxVEjQU6IdCjwm&notify_self"), myToken.Token)
        
        While Not socket.State = WebSocketState.Open
            Application.DoEvents()
        End While


        Dim count As Integer = 0

        While socket.State = WebSocketState.Open
            Dim receiveResult As WebSocketReceiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, 0, receiveBuffer.Length - 1), CancellationToken.None)

            Dim receivedString = Encoding.UTF8.GetString(receiveBuffer, 0, count)
            Dim echoString = "You said " & receivedString
            Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(echoString))
            'Await socket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)

            'Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))

            If receiveResult.MessageType = WebSocketMessageType.Close Then
                Await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, CancellationToken.None)
            ElseIf receiveResult.MessageType = WebSocketMessageType.Binary Then
                Await socket.CloseAsync(WebSocketCloseStatus.InvalidMessageType, "Cannot accept binary frame", CancellationToken.None)
            Else
                count = receiveResult.Count

                While receiveResult.EndOfMessage = False

                    If count >= maxMessageSize Then
                        Dim closeMessage As String = String.Format("Maximum message size: {0} bytes.", maxMessageSize)
                        Await socket.CloseAsync(WebSocketCloseStatus.MessageTooBig, closeMessage, CancellationToken.None)
                        Return False
                    End If

                    receiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, count, maxMessageSize - count), CancellationToken.None)
                    count += receiveResult.Count
                End While
                Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))

            End If
        End While
        Return False
    End Function

    Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        For Each MySocket As ClientWebSocket In MySockets
            If MySocket.State = WebSocketState.Open Then
                Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes("Got it!" & Now.TimeOfDay.ToString))
                Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))
                Await MySocket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)
            End If
        Next
    End Sub
End Class

100

101

102

103

104

105

106

107

108

109

Imports System.Net

Imports System.Net.WebSockets

Imports System.Text

Imports System.Threading

Public Class Form1

Const maxMessageSize As Integer = 1024

Dim receiveBuffer As Byte() = New Byte(1023) {}

Dim MySockets As New List(Of System.Net.WebSockets.ClientWebSocket)

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

Dim socket As New System.Net.WebSockets.ClientWebSocket

MySockets.Add(socket)

Dim result As Task(Of Boolean) = myTask(socket)

Exit Sub

While result.Status <> TaskStatus.RanToCompletion

Application.DoEvents()

End While

Debug.WriteLine(result.Status & " result: " & result.Result) ' "WaitingForActivation"

Exit Sub

ThisTest()

Exit Sub

End Sub

Public Async Sub ThisTest()

Dim ws = New System.Net.WebSockets.ClientWebSocket

' optional: ignore certificate errors

Net.ServicePointManager.ServerCertificateValidationCallback = Function(s, c, h, d) True

Try

Await ws.ConnectAsync(New Uri("wss://demo.piesocket.com/v3/channel_1?api_key=oCdCMcMPQpbvNjUIzqtvF1d2X2okWpDQj4AwARJuAgtjhzKxVEjQU6IdCjwm&notify_self"), Nothing)

If (ws.State = WebSockets.WebSocketState.Open) Then

Debug.Print("Opened.")

Await ws.SendAsync(New ArraySegment(Of Byte)(System.Text.Encoding.UTF8.GetBytes("{ ""message"":""hello""}")), WebSockets.WebSocketMessageType.Text, True, Nothing)

Dim bytes(4096) As Byte

Dim answ = New ArraySegment(Of Byte)(bytes)

Await ws.ReceiveAsync(answ, Nothing)

Debug.Print("answer:" + System.Text.Encoding.UTF8.GetString(answ.Array))

Else

Debug.Print("Not opened?!")

End If

Catch

Debug.Print("Error.")

End Try

End Sub

Private Async Function myTask(socket As System.Net.WebSockets.ClientWebSocket) As Task(Of Boolean)

Dim myToken As New CancellationTokenSource(5000)

Net.ServicePointManager.ServerCertificateValidationCallback = Function(s, c, h, d) True

Await socket.ConnectAsync(New Uri("wss://demo.piesocket.com/v3/channel_1?api_key=oCdCMcMPQpbvNjUIzqtvF1d2X2okWpDQj4AwARJuAgtjhzKxVEjQU6IdCjwm&notify_self"), myToken.Token)

While Not socket.State = WebSocketState.Open

Application.DoEvents()

End While

Dim count As Integer = 0

While socket.State = WebSocketState.Open

Dim receiveResult As WebSocketReceiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, 0, receiveBuffer.Length - 1), CancellationToken.None)

Dim receivedString = Encoding.UTF8.GetString(receiveBuffer, 0, count)

Dim echoString = "You said " & receivedString

Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes(echoString))

'Await socket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)

'Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))

If receiveResult.MessageType = WebSocketMessageType.Close Then

Await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, CancellationToken.None)

ElseIf receiveResult.MessageType = WebSocketMessageType.Binary Then

Await socket.CloseAsync(WebSocketCloseStatus.InvalidMessageType, "Cannot accept binary frame", CancellationToken.None)

Else

count = receiveResult.Count

While receiveResult.EndOfMessage = False

If count >= maxMessageSize Then

Dim closeMessage As String = String.Format("Maximum message size: {0} bytes.", maxMessageSize)

Await socket.CloseAsync(WebSocketCloseStatus.MessageTooBig, closeMessage, CancellationToken.None)

Return False

End If

receiveResult = Await socket.ReceiveAsync(New ArraySegment(Of Byte)(receiveBuffer, count, maxMessageSize - count), CancellationToken.None)

count += receiveResult.Count

End While

Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))

End If

End While

Return False

End Function

Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

For Each MySocket As ClientWebSocket In MySockets

If MySocket.State = WebSocketState.Open Then

Dim outputBuffer As ArraySegment(Of Byte) = New ArraySegment(Of Byte)(Encoding.UTF8.GetBytes("Got it!" & Now.TimeOfDay.ToString))

Debug.WriteLine("I Recv: " & System.Text.ASCIIEncoding.ASCII.GetString(receiveBuffer))

Await MySocket.SendAsync(outputBuffer, WebSocketMessageType.Text, True, CancellationToken.None)

End If

End Sub

End Class

Other useful links on this topic I found:

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_server

https://www.esegece.com/websockets/main-components/net-components/net-websocket-client

https://mcguirev10.com/2019/08/17/how-to-close-websocket-correctly.html

Use this if you’d like to connect with powershell!

Try{  
    Do{
        $URL = 'ws://YourDOmain.com/WebSocketHandler.ashx'
        $WS = New-Object System.Net.WebSockets.ClientWebSocket                                                
        $CT = New-Object System.Threading.CancellationToken
        $WS.Options.UseDefaultCredentials = $true

        #Get connected
        $Conn = $WS.ConnectAsync($URL, $CT)
        While (!$Conn.IsCompleted) { 
            Start-Sleep -Milliseconds 100 
        }
        Write-Host "Connected to $($URL)"
        $Size = 1024
        $Array = [byte[]] @(,0) * $Size

        #Send Starting Request
        $Command = [System.Text.Encoding]::UTF8.GetBytes("ACTION=Command")
        $Send = New-Object System.ArraySegment[byte] -ArgumentList @(,$Command)            
        $Conn = $WS.SendAsync($Send, [System.Net.WebSockets.WebSocketMessageType]::Text, $true, $CT)

        While (!$Conn.IsCompleted) { 
            #Write-Host "Sleeping for 100 ms"
            Start-Sleep -Milliseconds 100 
        }

        Write-Host "Finished Sending Request"

        #Start reading the received items
        While ($WS.State -eq 'Open') {                        

            $Recv = New-Object System.ArraySegment[byte] -ArgumentList @(,$Array)
            $Conn = $WS.ReceiveAsync($Recv, $CT)
            While (!$Conn.IsCompleted) { 
                    #Write-Host "Sleeping for 100 ms"
                    Start-Sleep -Milliseconds 100 
            }

            #Write-Host "Finished Receiving Request"

            [System.Text.Encoding]::utf8.GetString($Recv.array)


        }   
    } Until ($WS.State -ne 'Open')

}Finally{

    If ($WS) { 
        Write-Host "Closing websocket"
        $WS.Dispose()
    }

}

Try{

Do{

$URL = 'ws://YourDOmain.com/WebSocketHandler.ashx'

$WS = New-Object System.Net.WebSockets.ClientWebSocket

$CT = New-Object System.Threading.CancellationToken

$WS.Options.UseDefaultCredentials = $true

#Get connected

$Conn = $WS.ConnectAsync($URL, $CT)

While (!$Conn.IsCompleted) {

Start-Sleep -Milliseconds 100

}

Write-Host "Connected to $($URL)"

$Size = 1024

$Array = [byte[]] @(,0) * $Size

#Send Starting Request

$Command = [System.Text.Encoding]::UTF8.GetBytes("ACTION=Command")

$Send = New-Object System.ArraySegment[byte] -ArgumentList @(,$Command)

$Conn = $WS.SendAsync($Send, [System.Net.WebSockets.WebSocketMessageType]::Text, $true, $CT)

While (!$Conn.IsCompleted) {

#Write-Host "Sleeping for 100 ms"

Start-Sleep -Milliseconds 100

}

Write-Host "Finished Sending Request"

#Start reading the received items

While ($WS.State -eq 'Open') {

$Recv = New-Object System.ArraySegment[byte] -ArgumentList @(,$Array)

$Conn = $WS.ReceiveAsync($Recv, $CT)

While (!$Conn.IsCompleted) {

#Write-Host "Sleeping for 100 ms"

Start-Sleep -Milliseconds 100

}

#Write-Host "Finished Receiving Request"

[System.Text.Encoding]::utf8.GetString($Recv.array)

}

} Until ($WS.State -ne 'Open')

}Finally{

If ($WS) {

Write-Host "Closing websocket"

$WS.Dispose()

}

Handling WebSockets without SignalR in ASP.NET 4

Leave a comment

Cancel reply