[Opensim-dev] "Friendly teleports" between the standalone sims

[Dalien Talbot]

Folks,

wanted to check your opinion on this.

I've slowly started hacking up the code to try out my idea of "friendly
teleports".

The way I am playing with it is by making the "hybrid backend services" - a
backend services class has the LocalBackEndServices as a class member, first
redirects all of the calls to it, and then handles the "failure" cases  in
InformRegionOfChildAgent, ExpectAvatarCrossing, AcknowledgeAgentCrossed,
RequestNeighbourInfo.

The latter retrieves the regioninfo from the "remote regions cache" - hash
indexed by the regionid, which would need to be populated within the flow of
the said os* function.

The rationale for making the "overlay class" is to avoid the duplication of
the functionality of  "same-server" functions which are there already in the
local backend services - and have just the "intergrid" functions using the
remoting which I snarf from the OGS1 backend services code.

Since the regionhandle seems to be quite tied to the grid coordinates, I am
thinking of the following scheme:

1) I add a new os* function, which would take the URL of the sim + the
coordinates as the parameter. (could be a PATH_INFO-like scheme, i.e.:
http://sim-domain-name/path_to_handler_or_sim_name_in_case_of_grid/x/y/z

2) when the user script calls this function, the source sim A retrieves the
info about the destination sim (grid) B via this URL (the mainly interesting
stuff for the current implementation is the remoting IP/port) - but might
change in the future. This is the point where the user might get a dialog
box "do you want to teleport to ..."

3) A and B need to negotiate a "temporary" regionHandle, which would be
unused in both sims (grids).

3a) A sends a request with the proposed region handle to sim B
3b) if this regionhandle is ok - then B responds to it, else it responds
with "NAK", and proposes its own region handle.
3c) A does the same - if still not ok, selects the new temp region handle
and the story repeats. If after N attempts we do not succeed, the teleport
is declared as failed. If it succeeds, then both A and B have in the cache
the info about the temporary handle.

4) the user is sent to the target sim B using the
scene.RequestTeleportLocation()

5) once the user arrives, the sim (grid) B initiates a second teleport to
the "real" region and signals back to sim (grid) A that the temporary
location there can be cleared.

once the teleport succeeds, the sim(grid) B clears the temporary location as
well. The temporary locations would be probably cutting off the chunk of the
topmost X/Y coordinates.

This is a raw idea, I still need to test it further, but I think it might
work..

/d

p.s. I do not open yet the can of worms with the inventory, etc. :)
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