[sldev] Gesture client code Re: Anyone here with OpenCV experience?

[Philip Rosedale]

Hmmm.  We're spending more time on this in conversation than the time 
required to write the code, I fear. Bummer. 

Well, practically speaking, we've got an intern starting who is going to 
write some code to try to do this thing.  If our team does this, we will 
do it as best we can and get some code submitted.  We've read this 
thread, so thanks.  I think our direction will be to use UDP.  We will 
do what we can and show everyone when we have working code.

P



John Hurliman wrote:
> UDP is a poor choice for creating pipes between applications. I don't 
> know how OSX behaves, but the networking stack in the flavors of Linux 
> I'm familiar with and all versions of Windows are designed to drop UDP 
> packets; even on the loopback connection. When you hit a certain 
> frequency of message delivery (which is easy to do on loopback) you 
> will start consistently dropping some percentage of the data. Even if 
> you design your protocol around accepting random data loss, the 
> deterministic way that packets are dropped will almost always lead to 
> unacceptable results.
>
> As a side note, there is a growing body of evidence that suggests TCP 
> will outperform UDP even in cases where UDP would be the logical 
> choice. Decades of testing and tuning, careful synchronization of 
> implementations (see RFC 1122 and 2988 for example), hardware 
> acceleration of the TCP/IP stack, and a prioritization of TCP over UDP 
> in today's routing hardware gives it a seriously unfair advantage. 
> This isn't really related to the choice of protocol for creating a 
> local pipe though.
>
> John
>
> On Fri, May 22, 2009 at 4:23 PM, Philip Rosedale <philip at lindenlab.com 
> <mailto:philip at lindenlab.com>> wrote:
>
>     Looks like DBus is TCP based - that still seems unneeded, I think we
>     should use UDP,  what think?
>
>     Jan Ciger wrote:
>     > XML is definitely an overkill and certainly shouldn't be used for
>     > anything that has aspirations to be lightweight.
>     >
>     > Just use DBus - that is pretty standard and portable lightweight RPC
>     > mechanism and it is in the viewer already - it is used for passing
>     > slurls to the viewer from Linux browser.
>     >
>     > That would also allow easy scripting of the viewer in the future.
>     >
>     > Regards,
>     >
>     > Jan
>     >
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