CODEWITHSUNDEEP
c#asyncsockettcp
Ras
Ras

Reputation: 628

Reading buffer asynchronously over TCPIP client connection

I wrote a client which connect to a medical machine over TCP/IP. That machine send me XML files based on internal triggered event. I have to catch those XML and store on filesystem. I used a class which provide asynchronous connection and works fine except for few things: when I check the written files I noticed that they contains two xml separated by a null value (coded as 0X00). So I put a kind of filter on buffer but the problem remains. Basically I have to break my buffer when I detect the end of an XML file.

This is the code that provide async read:

try
{
    NetworkStream networkStream = this.client.GetStream();                
    int read = networkStream.EndRead(asyncResult);

    if (read == 0)
    {
        if (this.Disconnected != null)
            this.Disconnected(this, new EventArgs());
    }

    byte[] buffer = asyncResult.AsyncState as byte[];
    if (buffer != null)
    {
        byte[] data = new byte[read];
        Buffer.BlockCopy(buffer, 0, data, 0, read);
        networkStream.BeginRead(buffer, 0, buffer.Length, this.ClientReadCallback, buffer);
        content.Append(Encoding.UTF8.GetString(buffer.TakeWhile((b, index) => index <= read).Where(b => b != 0x00).ToArray()));

        // Store the file
        string machineId = StoreFile(content.ToString());

        counter++;
        if (this.DataRead != null)
            this.DataRead(this, new DataReadEventArgs(data));
    }
}
catch (Exception ex)
{
    Logger.Log(ex.Message);
    if (this.ClientReadException != null)
        this.ClientReadException(this, new ExceptionEventArgs(ex));
}

Upvotes: 0

Views: 522

Answers (1)

Cory Nelson
Cory Nelson

Reputation: 29981

The problem is that you're cutting off the start of the second XML document, but then continuing to read. The next read will not have a 0, so you will write its contents.

Read: XML1
Read: XML1 \0 XML2 <-- you cut this XML2 off
Read: XML2 <-- but then continue reading here.

Upvotes: 1

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