Sending Array of Bytes from Client to server?

Question

I've a tcp based client-server application. I'm able to send and receive strings, but don't know how to send an array of bytes instead.

I'm using the following function to send a string from the client to the server:

static void Send(string msg)
{
    try
    {
        StreamWriter writer = new StreamWriter(client.GetStream());
        writer.WriteLine(msg);
        writer.Flush();
    }
    catch
    {
    }
}

Communication example

Client sends a string:

Send("CONNECTED| 84.56.32.14")

Server receives a string:

void clientConnection_ReceivedEvent(Connection client, String Message)
{
    string[] cut = Message.Split('|');
    switch (cut[0])
    {
        case "CONNECTED":
            Invoke(new _AddClient(AddClient), client, null);
            break;
        case "STATUS":
            Invoke(new _Status(Status), client, cut[1]);
            break;
    }
}

I need some help to modify the functions above in order to send and receive an array of bytes in addition to strings. I want to make a call like this:

Send("CONNECTED | 15.21.21.32", myByteArray);

An empty catch block ist always a rather bad idea.

Uwe Keim
– Uwe Keim

2012-05-05 18:43:24 +00:00
Commented May 5, 2012 at 18:43 — Uwe Keim
– Uwe Keim, Commented May 5, 2012 at 18:43

Marc Gravell · Accepted Answer · 2012-05-05 18:41:27Z

Just use Stream - no need for a writer here. Basic sending is simple:

stream.Write(data, 0, data.Length);

However you probably need to think about "framing", i.e. how it knows where each sun-message starts and ends. With strings this is often special characters (maybe new line) - but this is rarely possible in raw binary. A common appoach is to proceed the message with the number f bytes to follow, in a pre-defined way (maybe network-byte-order fixed 4 byte unsigned integer, for example).

Reading: again, use the Stream Read method, but understand that you always need t check the return value; just because you say "read at most 20 bytes" doesn't mean you get that many, even if more is coming - you could read 3,3,3,11 bytes for example (unlikely, but you see what I mean). For example, to read exactly 20 bytes:

var buffer = new byte[...];
int count = 20, read, offset = 0;
while(count > 0 && ((read = source.Read(buffer, offset, count)) > 0) {
    offset += read;
    count -= read;
}
if(count != 0) throw new EndOfStreamException();

jgauffin · Accepted Answer · 2012-05-05 19:09:04Z

0

Since you seem new to networking you might want to use WCF or another framework. I've just written an article about my own framework: http://blog.gauffin.org/2012/05/griffin-networking-a-somewhat-performant-networking-library-for-net

You need to use a header for your packets as Mark suggested, since TCP uses streams and not packets. i.e. there is not 1-1 relation between send and receive operations.

answered May 5, 2012 at 19:09

jgauffin

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Comments

Bing Bang · Accepted Answer · 2018-09-22 20:14:29Z

0

This is the same problems I'm having. I only code the client and the server accepts byte arrays as proper data. The messages start with an ASCII STX character preceded by a bunch of bytes of any values except the STX and ETX characters. The message ends with a ETX ASCII CHARACTER. In C I could do this in my sleep, but I'm learning C# on the job. I don't understand why you would send bunches of double byte unicodes when single byte ASCII codes work just as well. Wasting double the bandwidth.

answered Sep 22, 2018 at 20:14

Bing Bang

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