From: "Dan Cooperstock" <dcoops@...>

>
> That idea is fairly similar to the idea someone on an ASP
> (Association of Shareware Professionals) forum suggested, which is to
> send out a multicast UDP packet on startup, that other instances of
> my program on the same subnet respond to with "Yes, I'm here". The
> sender counts the responses, and if they exceed the licensed # of
> users (minus one, to allow the sender to run), prevents the sender
> from running.
>
> This actually seems a bit simpler, because it doesn't need a server
> program, and isn't affected by crashes.
>
> Any comments on that idea? Thanks.

It's fairly easy to implement UDP communication on most networks. I do it in
the programs I write to allow an admin to send messages to anyone running
the program on the network. The biggest problem I see with this approach to
your problem is the lag time of networks. The program would have to wait x
amount of seconds to make sure it received a broadcast in case of major
network traffic. If that isn't a problem, then it could work but the
possibility of running more users than are allowed because of timing issues
might show up from time to time.

Woody (TMW)