a *fast* check for whether another machine is on the local network?

[Dar Scott]

A lot of things can be done in the background using the natural GUI events, the myriad of LiveCode messages and send in time.  Most interfaces have a callback scheme to allow this.  Event style programming works well with this.  

Whether you can do that directly with your db interface depends on what you are using.   If you are using the revDatabase commands, then maybe you can't.  I'm not familiar with those; I don't use them.  Others can advise better.  However, other interfaces might work with callbacks.  

If your db interface does not work with callbacks, then you might have to launch a separate app and communicate with that.  That communication would then have callbacks and messages that allow things to work in the background.  You can use TCP/IP for communication or maybe stdin/stdout depending on the development of LiveCode.

A hint about that "datagram" thing:  The datagram is not that important.  What's important is that you can open the socket without any handshake dialog such as that needed to set up the TCP link.  However, if Alex's idea works, it will force the communication layer below TCP (such as Ethernet) to send a message to find out who has that IP address, but only if it does not already have it.  So, if you were connected to that machine in the last 20 minutes (on OS X), the method does not trigger a query to find the hardware that has that IP address.  Getting that IP-to-hardware association is the minimal communication that can be done to confirm the machine is there.  It depends on whether the open will really trigger such a query if the address is not known.  Alex thinks it does.  

Dar


On Jun 14, 2013, at 6:23 PM, Dr. Hawkins wrote:

> On Fri, Jun 14, 2013 at 11:10 AM, Dar Scott <dsc at swcp.com> wrote:
>> Why not try to open the db?  Perhaps in the background
> 
> In the background?  If I could do livecode things in the background,
> it would solve nearly *all* of my problems.
> 
> *Is* there a way to do background things?
> 
> And now I'm off to learn about this "datagram" thing . . .
> 
> 
> -- 
> Dr. Richard E. Hawkins, Esq.
> (702) 508-8462
> 
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