Re: [Nel] Dynamic load balancing?

[Vincent Archer]

According to Thierry Mallard:
> On Tue, Feb 20, 2001 at 11:21:38AM -0300, Nahuel Greco wrote:
> > [... case of zone server failure ...]
> > Then, you has the map divided in zones,... if a geographic server dies, 
> > other
> > will be taking the zone that belong to the died server? .. 
> 
> The problem here will be persistency (is that english ? ;-). All the data
> currently in memory on server A, which is failing, will be lost for server B
> which is supposed to take over.

That's what you get with a purely geographic design, like EQ/UO design.
When a zone fails, you get kicked out, everything you gained since your last
save is lost, and when you return, every single critter has respawned. All
state is lost, since all state was located in a single process.

With a functional approach, all game entities are "holographic"
regarding to storage. They're a kind of "cloud" of various agents located
on various services. If a geographic server dies, you get suddendly
a kind of fog for a while. Another service starts up, gets back information
about what critters are where from the AI services, where all players are
from the various player services, and what items are grown where from the
ecology services. It takes a little time, but you recover more
gracefully.

The same occurs if an AI server dies. Those critters that were managed
by that service freezes, but then another service takes them over. They
will probably forget a lot of what they were doing, but they don't "depop",
since the geography service knows that there's that kind of beast
that was located there.

Of course there are services that are more critical than other. If a login
service dies, all players using it are kicked out forcefully. If the
item manager dies, your inventory locks up completely (but you still look
like yourself, can move around, and talk).

-- 
Vincent Archer                                         Email: address@hidden

Nevrax France.                              Off on the yellow brick road we go!