RE: [Once development] An Essay about mmorpg performance

[<Cir...@cs...>]

Well, about that essay:

1)  Nothing in it is applicable to Once due to its current design, =
except possibly for the 200 UDP connections - but 200 UDP or 200 TCP - =
what's the difference?  TCP behaves badly when you have long lags  (5s =
or more on round trip) - admittedly you wouldn't play under those =
conditions...

2)  The discussion on UDP vs TCP doesn't make any sense at all.  I have =
used sockets a fair bit over the years (although I never made much use =
of UDP until now - normally I only use it to broadcast messages to =
discover services like DHCP etc) so I had to learn quick about this =
'reliable UDP' stuff and ask all sorts of questions - and one great =
thing about UDP is that a lot of data sent can be lost and we don't care =
- for them we use unreliable packets (normal UDP) and if they're lost - =
so what.  TCP would guarantee that they are sent, so network glitches =
can cause some situations which are much more annoying with TCP than =
UDP.  In RakNet, we send all unreliable packets as 'ordered' - if the =
packet is an unreliable type and comes after an  unreliable packet which =
was sent later, the packet is dropped - our server never knows about it =
and doesn't have to handle it, which is the correct behavior.  In TCP =
time is wasted guaranteeing the retransmission and order of that packet =
even though the packet is not very important. =20

 As for gaining levels by sending a message multiple times - that is =
only possible through incredibly bad game design and as easy to do with =
TCP as with UDP - the network is really not an issue in that case.  As =
for 'real-time', that is only an illusion. There is lag and we can't =
beat that (in fact there have been some bad days with PS where the lag =
is really annoying).   Effects need to be created in such a way that =
even if people move a little etc, you get the impression that the target =
was hit; equally important you want it to look like the target was =
missed if in fact you missed it.  You don't want a player screaming "I =
saw my arrow hit him but I got the  message 'you missed' !"  You also =
want to avoid the situation where you killed your opponent and suddenly =
you see a spell that he cast hit you.  Most of the illusion (especially =
with spells) is created by building a lag into your actions.  For =
example, you begin to draw your bow - it's annying that you don't fire =
instantaneously because it gives the enemy a chance to move - just like =
in the 'real' world. Because you know that, you're annoyed but not angry =
when you see the arrow miss, and you're very happy if you see it hit.=20

  I won't say anymore about network stuff - we have decided on our new =
net library and it works well.  You can read articles on =
www.gamasutra.com  if you want to know what the commercial game =
developers have to say on the TCP vs UDP topic.