On Jul 10, 12:38 pm, samwyse <[EMAIL PROTECTED]> wrote: > On Jul 10, 1:50 pm, Guy Davidson <[EMAIL PROTECTED]> wrote: > > > Hi Folks, > > > I'm having some issues with an small socket based server I'm writing, > > and I was hoping I could get some help. > > > My code (attached below) us supposed to read an HTTP Post message > > coming from a power meter, parse it, and return a proper HTTP 200 Ok > > message. The problem is that the socket fails to send the entire > > message as one message, creating a fragmented message which the power > > meter then fails to read and accept. > > > Is there any way to force the socket to send the entire message at > > once? Am I doing anything wrong? Is there an easier way to implement > > this functionality? > > By 'message', do you mean a single IP datagram? In general, the > answer is no. Each call to 'connection.send()' will (in general, see > the next paragraph) transmit as much data as will fit into a single IP > datagram, given the current MTU for the transmission circuit. The > fact that you're calling it in a loop indicates that the data being > sent may be larger than will fit into a datagram. > > Or, by 'message', do you mean a single TCP segment? Again, the answer > is no. Your network stack will try to make the TCP segments the right > size to fit within a single IP datagram, leading to the same result as > above. > > From your description, I get the feeling that your power meter has a > broken network stack, and you're trying to program around it. You > need to repair the meter.
Here's the weird thing. I know it should be able to be done. Let me try and explain in some more depth what I'm trying to do: The meter sends HTTP Post messages, and expects, as a reply, an HTTP 200/Ok message. I try to send the following message, using the socket.send() command: 'HTTP/1.1 200 OK\r\nDate: Thu, 10 July 2008 14:07:50 GMT\r\nServer: Apache/2.2.8 (Fedora)\r\nX-Powered-By: PHP/5.2.4\r\nContent-Length: 4\r \nConnection: close\r\nContent-Type: text/html; charset=UTF-8\r\n\r \n[0]\n' However, when I snoop on the packets in wireshark, here's what I see: HTTP/1.1 200 Ok: HTTP/1.1 200 OK Date: Wed, 09 July 2008 14:55:50 GMT Server: Apache/2.2.8 (Fedora) X-Powered-By: Continuation or non-HTTP traffic: PHP/5.2.4 Content-Length: 4 Connection: close Content-Type: text/html; charset=UTF-8 [0] It splits into two packages, which the meter can't read, and the communication breaks down there. Any ideas? Thanks. -- http://mail.python.org/mailman/listinfo/python-list
