Using data from the DataReceived event in WinForms

[DVonk]

Hello,

first of all - I just recently came across your project after trying to use TcpClient myself and encountering a lot of problems. It's really simple to use and works great so far, so thank you for that. I have one issue though:

How do I actually use the data I'm receiving from the server in DataReceived outside of that function? For example, I want to do this inside of DataReceived on the client's side:
textBox.text = $"[{e.IpPort}] {Encoding.UTF8.GetString(e.Data)}"
This just doesn't do anything, and it even seems to abort the connection without calling ClientDisconnected, as repeated calls of client.Send() lead to this error:

Not connected to the server; use Connect() first.

That does not happen when I display the data with MessageBox.Show(), or set a variable to the data. But if I then try to set the TextBox to the variable, nothing happens and the connection aborts.

I'm guessing that this is a threading issue, since I'm trying to change data in the main UI thread. So my question is - how is it intended to get the data out of this DataReceived event, so I can use it normally with the rest of my software?

Thank you in advance.

[jchristn]

Hi @DVonk thanks for the kind words. It likely is indeed a threading problem and where the client runs vs the UI thread.

I have a very similar TCP project called WatsonTcp (main difference is WatsonTcp uses a framing layer, SuperSimpleTcp does not) and in that repo I have a test client for Windows forms. Please take a look and let me know if this helps. Syntactically the two projects are almost identical.

https://github.com/jchristn/WatsonTcp/blob/master/Test.WinFormClient/ClientForm.cs

Specifically:

private void Logger(Severity sev, string msg)
        {
            // If this is called by another thread we have to use Invoke           
            if (this.InvokeRequired)
                this.Invoke(new _LogDelegate(Logger), new object[] { sev, msg });
            else
                label1.Text += Environment.NewLine + "[" + sev.ToString().PadRight(9) + "] " + msg;
        }

        private void MessageReceived(object sender, MessageReceivedEventArgs e)
        {
            Logger(Severity.Debug, "Message from " + e.IpPort + ": " + Encoding.UTF8.GetString(e.Data));
        }

[DVonk]

Thank you for the link to the other repository. I've taken a look, but it seems unsuitable as it says I have to use WatsonTcp for the server as well. I do not have control over the server however, I'm just trying to build a TcpClient that can communicate with a closed source server for which I have nothing but IP address and port.

So, is it correct that there's actually no way to get the data from SuperSimpleTcp out of the thread it uses? I mean, that's kind of what Tcp is used for - to get data from a server and do something with it in your program.

[jchristn]

Hi @DVonk I think you may have misinterpreted. WatsonTcp and SuperSimpleTcp are very similar in terms of implementation. I wasn't implying that you should use WatsonTcp, but rather, use the model/implementation shown in the WatsonTcp TestWinFormClient project. That code, though written for WatsonTcp, should work as well for SuperSimpleTcp.

[DVonk]

Ah, I got you. I've managed to use .Invoke() to work around the issue and I can display the received text in my UI now. Thank you!