[VB2008/.NET 3.5] Asynchronous TcpListener & TcpClient

[jmcilhinney]

I've been over the code numerous times and I've found no reason for it not to function correctly. Believe I'm just going to move on and hope you decide to rewrite this library at some point in time for C# and/or .NET 4 or 4.5.

That wouldn't help.

[yfzpurgatory]

That wouldn't help.

I don't see why it wouldn't when something about C# is causing it not to function correctly. When I use the library in VB.NET 2010 everything works just fine; zero problems that I haven't fixed myself. When I try the same in C# 4 it's a completely different story. For some reason it just isn't jiving well on these lines:

Protected Overridable Sub OnConnectionAccepted(ByVal e As ConnectionEventArgs)
        Me._synchronisingContext.Post(AddressOf RaiseConnectionAccepted, e)
End Sub

Nothing has been changed, and I know I'm not going crazy. I've ran over the entire library multiple times, and I've very thoroughly went over both the read and send methods line by line to no avail. It has left me completely dumbfounded. The only event that is raised is MessageReceived; both ConnectionClosed and ConnectionAccepted fail, although the client connects.

[Nightwalker83]

I don't see why it wouldn't when something about C# is causing it not to function correctly. When I use the library in VB.NET 2010 everything works just fine; zero problems that I haven't fixed myself. When I try the same in C# 4 it's a completely different story. For some reason it just isn't jiving well on these lines:

Please stop talking about "C#" in this thread/section. If have a C# question post it here.

[yfzpurgatory]

Please stop talking about "C#" in this thread/section. If have a C# question post it here.

When the problem is 100% relevant to this topic and this library, no, I don't think I will. What I will do, however, is completely wash my hands of this library. An "MVP" my ass.

[drankof]

... nothing is being assigned to the _synchronisingContext field, so you need to work out why. ... SynchronizationContext.Current will return a null reference if you're not using it in either a WinForms or WPF application.

FOREWORD: I opened my account on this forum today for two reasons; 1) to continue discussing a legitimate question in a reasonable tone, and more importantly, to say that this code is the most amazing code I have ever gotten off the internet. Seriously. I'm also a new guy to .net, coming from AmigaBasic (joke, vb6) 1 month ago. In my month of scouring the internet looking and learning to make test programs to learn the language, I have BY FAR learned more from this code than from anything else. Multiple programs from one solution, all while sharing and building a library, with all sorts of fancy commenting and region stuff I never knew existed. The library implements great into other programs, too! THANK YOU so much. I'm a big fan.

That said, I'm working in VB2010 (.net 4.0) and am bumping into a similar issue. The server (as far as I can tell) must be run from a form in order for the SynchronizationContext.Current to not return a null value.

Making a Windows Forms Application launched from sub main (to make it behave as similar as possible to module-based code), I put the following in a blank new form's code (it's basically just a stripped down version of the test server):

Module serverModule
    Public Sub main()
        serverWindow.Show()
        Application.Run()
    End Sub
End Module

Public Class serverWindow

    Public WithEvents server As New MessageServer(12345)
    Public ReadOnly hosts As New List(Of HostInfo)

    Private Sub server_ConnectionAccepted(ByVal sender As Object, ByVal e As Net.ConnectionEventArgs) Handles server.ConnectionAccepted
        hosts.Add(e.Host)
    End Sub

    Private Sub server_MessageReceived(ByVal sender As Object, ByVal e As Net.MessageReceivedEventArgs) Handles server.MessageReceived
        server.Send(e.Message)
        If e.Message = "exit" Then Me.Close()
    End Sub

    Private Sub server_ConnectionClosed(ByVal sender As Object, ByVal e As Net.ConnectionEventArgs) Handles server.ConnectionClosed
        Dim host = e.Host
        hosts.Remove(host)
    End Sub

    Private Sub MainWindow_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        server.Dispose()
        Application.Exit()
    End Sub
End Class

Clients can connect and talk, the server repeats the chat, and clients can even shut down the server with "exit". The server only has a single blank window running, which I guess could be hidden, but I what I originally wanted was to run the server from a module.

A nearly identical module-based version:

Module serverModule

    Public Sub main()
        Application.Run()
    End Sub

    Public WithEvents server As New MessageServer(12345)
    Public ReadOnly hosts As New List(Of HostInfo)

    Private Sub server_ConnectionAccepted(ByVal sender As Object, ByVal e As Net.ConnectionEventArgs) Handles server.ConnectionAccepted
        hosts.Add(e.Host)
    End Sub

    Private Sub server_MessageReceived(ByVal sender As Object, ByVal e As Net.MessageReceivedEventArgs) Handles server.MessageReceived
        server.Send(e.Message)
        If e.Message = "exit" Then shutdown()
    End Sub

    Private Sub server_ConnectionClosed(ByVal sender As Object, ByVal e As Net.ConnectionEventArgs) Handles server.ConnectionClosed
        Dim host = e.Host
        hosts.Remove(host)
    End Sub

    Private Sub shutdown()
        server.Dispose()
        Application.Exit()
    End Sub

End Module

Whenever a client joins, the same line "Me._synchronisingContext.Post(AddressOf RaiseConnectionAccepted, e)" says object reference not set to an instance of an object.

The same error occurs when I try to reproduce the same thing by running the server from a class (without a form). Yet the client seems to run great from a module.

So I guess the question is, would it, and if so, how would it be possible to run a server using your current library without it running from a form?