C# Client. Sending Data from C# Client to Java Server

Question

[SOLVED]

I have similar problem to the post here, have followed all the answers, but got empty string as response. data.
Here's my code :

try
{
   string ENDOFLINE = "\r\n";
   TcpClient client = new TcpClient(txtIP.Text, Int32.Parse(txtPort.Text));
   NetworkStream stream = client.GetStream();

   byte[] data = Encoding.ASCII.GetBytes(txtMessage.Text + ENDOFLINE);
   stream.Write(data, 0, data.Length);

   String responseData = String.Empty;
   Int32 bytes = stream.Read(data, 0, data.Length);
   responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
   Console.WriteLine("Received: {0}", responseData);
   stream.Close();
   client.Close();
}
catch(Exception ex)
{
   Console.WriteLine(ex.message);
}

Solution:

Disconnecting the connection right after sending the message and before receiving response. I followed this article

Please always post code in the question itself, not through external links, so the question does not become useless if the link dies. — Peter B
– Peter B, Commented Dec 29, 2016 at 8:21
@PeterB, thank you for your advice, I have edited the post :) — Budianto IP
– Budianto IP, Commented Dec 29, 2016 at 8:34
you cant send bytes array from C# to Java and VV because Java uses sbyte not byte ... you should change byte[] data = Encoding.ASCII.GetBytes(txtMessage.Text + ENDOFLINE); — Alrehamy
– Alrehamy, Commented Dec 29, 2016 at 8:41
@alrehamy, I could not get it working, do you have a sample or perhaps an article I can read? — Budianto IP
– Budianto IP, Commented Dec 29, 2016 at 9:13

Community · Accepted Answer · 2017-05-23 11:47:35Z

3

Your code works fine but only if the server-side is cooperative.

I tested it by having the simple java server implementation from Christian Tucker with a slightly altered run implementation:

public void run()
{
    while(isRunning)
    {
        try 
        {
            clientSocket = serverSocket.accept();
            System.out.println("Client Connected from " + clientSocket.getInetAddress().getHostAddress() + ":" + clientSocket.getPort());
            recv = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            System.out.println("Data Recieved: " + recv.readLine());

            // make sure to send something back ...
            OutputStreamWriter wr = new OutputStreamWriter(clientSocket.getOutputStream());
            wr.write("FuBar!\r\n");
            // and flush!
            wr.flush();

            clientSocket.close();
        }
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
}

Without calling flush on that OutputStreamWriter I got the same results as you: Data got send successfully but received an empty response.

It does help in these cases to have both ends running in a debugger.

edited May 23, 2017 at 11:47

CommunityBot

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answered Dec 29, 2016 at 12:13

rene

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2 Comments

Budianto IP Over a year ago

Interesting, I'm gonna check the one who developed the server side, hopefully this will solve my problem. I will accept your solution once it's confirmed. Thanks for your help.

Budianto IP Over a year ago

Hi, thank you for your help, I finally found the correct solution :)

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