Re: [ogpx] Teleports and protocol resilience

[Joshua Bell <[e-mail]>]

On Mon, Oct 12, 2009 at 10:13 PM, Morgaine
<[e-mail]>wrote;wrote:

> I suggest that the protocol define Derez and Rez as *concurrent* and *
> non-dependent* operations to avoid this situation.  The AD can mark R1 as
> disabled for all further agent state changes --- this will provide all the
> protection needed to prevent brief double-presence anomalies from being
> significant.  If a jammed R1 refuses to give up its hold on the avatar, then
> at least the user will not suffer from it.  Reaping dead simulator sessions
> then becomes a problem for the region operator alone, and not for the AD,
> the user, and the region as happens now.
>

Unresponsive origin regions are an excellent use case to consider.

One of the reasons that this fails today is that the origin RD maintains
some amount of agent state (e.g. script state for attachments). For a
sim-to-sim handoff, the origin RD must successfully transmit information
either to the AD or the destination RD (or both), otherwise the user
experience is poor (information is lost).  Note that this needs to happen
during a simple logoff/login as well. It seems to me that agent state in the
AD should have ACID-ish characteristics, including the agent's current
location.

Given that we must be able to describe behavior of closing a client-AD
connection when the RD is unresponsive (e.g. the host has dropped off the
network, etc), I'd be inclined to tackle unresponsive origins in similar
fashion for logout/login, region crossing, and teleport. (Which in the
current drafts are indeed tackled together.)

So: I would agree that the current behavior of SL is less than ideal - if
the source region is unresponsive (for some TBD definition), a teleport
should probably not fail. But to preserve user data (and preserve the user
experience), the initial transport attempt must involve a transaction
between the AD, source RD and destination RD.