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Re: Question on sending data over UDP endpoints
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Re: Question on sending data over UDP endpoints


  • Subject: Re: Question on sending data over UDP endpoints
  • From: Justin Walker <email@hidden>
  • Date: Wed, 30 Jun 2004 13:10:41 -0700

On Jun 30, 2004, at 13:00, Igor garnov wrote:

Hello,

My Carbon CFM application uses Open Transport and works with endpoints in asynchronous mode, installing a notifier routine.

if I use "OTSndUData" to send some data to a foreign host, should I also install an OT timer that fires in, say, 5 seconds if no reply is given, or will my notifier routine be called with "T_UDERR" code to indicate that the foreign host is down / is not listening on the port specified? Will I actually receive an ICMP message, which will consequently trigger "T_UDERR" event?

The spec for UDP sez that it is "unreliable". That means that you will receive no system notification, either from the local or remote systems, to indicate a problem in transmission or reception of datagrams.

It is up to your application to detect lost packets or other problems in communication.

I can't say for sure about OT on earlier versions of Mac OS, but on Mac OS X, you will receive no indication of error, regardless of whether the system runs out of buffers to hold your transmissions or the driver can't send the frame (e.g., because of excess collisions).

Regards,

Justin

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