[vworld-tech] DirectPlay for MMOG's

ceo ceo at grexengine.com
Fri Jan 16 01:16:29 PST 2004

dienw wrote:
> ----- Original Message -----
> From: "Phil Taylor" <ptaylor at ATI.COM>
>>during DX8 and DX9 betas the DPlay Maze sample was used to hook up >1000
>>simultaneous users.
>>        1)Reliable and unreliable delivery of messages. Reliable messages
>>will be resent until the target application receives them. You can assign
>>the delivery type on a message-by-message basis.
>>        2)Sequential and non-sequential delivery of messages. Sequential
>>messages will be passed to the target application in the order they were
>>        3)Message fragmentation and reassembly. If message size exceeds
> the
>>capacity of a particular network, DirectPlay automatically fragments and
>>reassembles the message.
>>        4)Congestion control. DirectPlay automatically throttles your
>>        5)Send prioritization. To ensure that the most important messages
>>        6)Message timeouts. To prevent the outgoing message queue from

Hmm. Obviously, I'm not criticising dienw, but that sounds like a 
completely useless answer to me.

1000 players is an irrelevant statistic without some basic info like:
   - latency
   - topology
   - traffic pattern

If that's for client/server it's also deeply unimpressive (if he'd said 
"> 10,000" at least we'd be talking about a serious server; > 20k and it 
would be impressive as a stat alone (although less so if this was with 
1% bandiwdth usage and 300ms latency ;)).

Most of the "benefits" sound like basic IP / UDP / TCP functionality. 
Automatic fragmentation? WOW!

"Congestion Control" ... who cares? What really matters is the algo... 
If it's equivalent to early TCP, it's worse than useless; if it's an 
implementation of the latest modern TCP CC algos, it's to-die-for.


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