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Reading from a socket

zorker
zorker asked
on
Medium Priority
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Last Modified: 2013-11-20
How do I use OnRecieve to read from a socket so that I can execute a block of code whenever
some data comes in on the socket?

Please be very detailed and specific, as I have little experience.
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Commented:
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Commented:
I have no control over the message format.  Basically what I want to happen is whenever
anything comes in on the IP socket, I want to write it to a com port (which I already
have all set up).  Should I just do it one byte at a time?

Also, regarding OnReceive:  Where do I call it or whatever?
Should I extend CAsyncSocket or can I just override an existing version
or what?  Also, will it automatically be called when data comes in, or do
I have to do something to the message map?

Author

Commented:
What happens if I read less than the amount of data on the buffer?
Does the rest get discarded, or does it move to the front of the buffer?

Commented:
Unfortunately, I don't know a way to find out how many bytes is in the in-buffer. So, if you don't know anything about the size of the messages you will receive, I guess the safest way is to read one at a time.

Make your own socket class, which inherits from CAsyncSocket. Then override the OnReceive method with your own. It will be called automatically.

If you read less data than is in the in-buffer, the rest will remain in the in-buffer. You will receive the following bytes with your next call to Receive.

Commented:
use the function AsyncSelect whit the flag FD_READ. The code is

void CChatClientDoc::Conecta()
{
      m_pSocket = new CChatSocket(this);

      if (!m_pSocket->Create())
      {
            delete m_pSocket;
            m_pSocket = NULL;
            AfxMessageBox(IDS_CREATEFAILED);
      }
      m_pSocket->Connect(m_sServer, m_uPort);
      m_pSocket->AsyncSelect(FD_READ | FD_CONNECT | FD_CLOSE );
}

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