[Solipsis-tech] RE : [Solipsis] some questions about Solipsis (from Taiwan)

[SIMON G. FTRD/DMI/I. <gwe...@rd...>]

Hi,

	[I include the solipsis list in this discussion]

	Both projects (yours and Solipsis) relies on the same concept:=20
1- each entity is connected with all entities located within its Area Of =
Interest (AOI)
2- each entity MAY be connected with some farther entities in order to =
ensure Global Connectivity (GC). These far neighbors are chosen thanks =
to a gemoetric rule (Voronoi for your project, an original and peculiar =
rule for Solipsis)

	Please find in the following some answers to your questions :

	Q2 : the entities execute a "mutual neighbor discovery" algorithm every =
time one of their neighbors move. Note that the AOI is not fixed. The =
number of neighbors within the SOI is in a small range (typically a =
fixed value k +/- 20%).

	Q3: we have to consider two proofs :
* are entities connected with all entities within AOI ? The answer is =
NO. You may find an illustration of the identified worst case in the =
draft of my PhD report (http://gwendal.simon.free.fr/Data/part1.pdf =
Figure 1.7 - page 17). Unfortunately, this report is written in french =
(due to a french law)
* does our rule ensure connectivity of the graph ? The answer is YES, if =
the world is a torus and if the convex hull of the set of all entities =
is the torus itself.

	Q4: in current implementation, an entity stops the lookup of entity as =
soon as it discovers another entity providing back the rule respect. It =
is possible to optimize this algorithm in order to stop later.
=09
	I have now some questions about your paper. You don't give much details =
about the construction and the maintaining of the Voronoi Diagram. What =
is the algorithmic complexity of Voronoi re-building (when joining, when =
moving, when leaving) ? What is the complexity of the "overlap-check" =
algorithm (Voronoi regions overlapping AOI) ?

	Best,

-- Gwendal


-----Message d'origine-----
De : Shun-Yun Hu [mailto:sy...@ya...]=20
Envoy=E9 : mercredi 9 juin 2004 02:16
=C0 : KELLER Joaquin FTRD/DMI/ISS
Objet : Re: [Solipsis] some questions about Solipsis (from Taiwan)


Hi Joaquin,

Thanks for the prompt reply. I've attached a current working draft of =
the paper to this e-mail.=20
It's still not camera-ready yet (due next monday), as I need to reduce =
it to 5 pages, and I'm planning to include a section of analysis on =
Solipsis :) (I wasn't aware of Solipsis when I first submited) =20

If you've any questions/comments/feedback, please do let me know, I'd =
very appreciate.

some additional questions, if you don't mind:

Q2. It's as I suspected, because checking seems to be necessary for =
those outside of SOI as well. I'm wondering about the frequency of the =
check. Does it happen every time someone in my SOI moves? or does it =
happen only between a certain interval. (this has =
performance/consistency impact on the design)

Q3. What is the case where it might not work? would you mind to let me =
know the special circumstance? If it's difficult to prove GC maintaince =
via mathmatical analysis, maybe simulation is the way. :)  We're also =
currently doing simulations only, as I can't think of a good way to =
analyze/prove topology maintaince. Have you any simulation results yet =
for Solipsis? (as in having 1000+ entities simulation)

Q4. I guess my question is, will the P2P topology be maintained in a =
deterministic way, or will hosts actually be able to connected in =
various ways due to chance circumstance. For example, when trying to =
maintain GC, you might start searching for a host to connect in the 180 =
degree "missing range". However, it certainly appears that it's possible =
for more than one host to "quality" as the node to connect to (for =
example, you could connect to the 1st host that satisifis the =
requirement, or the "best" host, define as that could reduce the =
"missing range angel" the most).

I've asked my friend (whose name is Peter) about collaboration, and I =
think both him and I are interested.. :) although personally I'm not =
that into language localization stuff.. :) I do hope for some form of =
collaboration, if possible, because to my amazement when I first saw =
your paper, I think both of us have the same ultimate goal, which is to =
realize some WWW-like virtual environment, pervasive and usable for all =
people. :) We even have the same literary reference in our paper (e.g. =
Matrix & Snow Crash), and this was before I read about your paper..=20

Cheers,

Shun-Yun


----- Original Message -----=20
From: KELLER Joaquin FTRD/DMI/ISS=20
To: Shun-Yun Hu ; SIMON Gwendal FTRD/DMI/ISS=20
Cc: sol...@li...=20
Sent: Wednesday, June 09, 2004 1:01 AM
Subject: RE : [Solipsis] some questions about Solipsis (from Taiwan)


Hi Shun-Yun,
I am happy to know there is a solipsis-like project elsewhere in the =
planet :-) Sure I want to get your netgames 2004 paper ! Your questions:
Q1: A list of nodes, at least some nodes should be alive. To get that =
list you can download it, (eg entities.met in the solipsis distrib) =
and/or while using Solipsis you keep memory of met entities so the list =
is frequently updated.
Q2: By now: Checking is done for all known entities (whether they are =
inside or outside SOI); When entity A detects that an entity B has =
entered the SOI of entity C, entity A sends out immediatly a message to =
entity C. If entity B is outside SOI of entity C, nothing occurs.=20
Q3: So so. We have proved that in some tricky cases it will not work. =
But we have strong hints that it should works most of the time (not =
proved).=20
Q4: I am not sure to fully understand this question. There are some =
deterministic rules to choose entities that will restore or keep GC =
(something like "take the nearest that fulfill GC property"). But all =
that is probably not very predictable since unpredictable network delays =
have a huge impact on rules like "take the first node you got and..."
Q5: The awareness radius, awareness area or SOI is enlarged or reduced =
in order to keep the number of entities inside in a certain range (say =
between 9 and 15).=20

Have fun,
-- Joaquin


BTW: we plan to handle multiple (human) languages in Solipsis GUI, and =
our first target (after english) is Chinese (simplified-mainland and/or =
classical-taiwanese) we will be happy if you and your friend contribute =
on that.=20
-----Message d'origine-----
De : Shun-Yun Hu [mailto:sy...@ya...]=20
Envoy=E9 : mardi 8 juin 2004 15:53
=C0 : KELLER Joaquin FTRD/DMI/ISS; SIMON Gwendal FTRD/DMI/ISS Objet : =
[Solipsis] some questions about Solipsis (from Taiwan)




Hello Joaquin and Gwendal,

I'm a CS graduate student in Taiwan, I've recently learned the very =
interesting and wonderful works you guys are doing at France Telecom =
R&D, on Solipsis.

I got very interested in your work because I've also been thinking about =
a massive P2P Virtual Environment that exists on the Internet, and I've =
been doing related studies and research since Sept. 2003, along with a =
good friend of mine.=20

I've only come across Solipsis recently, and had read through both of =
your papers. However, I've some questions raised in my mind. If you =
could answer these questions for me I'd very appreciated. :)=20

Q1. what's the bootstrap procedure? (i.e. how does a node join Solipsis =
initially? through a list of known nodes? or through a 'gateway server' =
of some sort?)

Q2. when, and how frequent does an entity check for mutual neighbor =
discovery? (every time when someone within the Sphere of Influence (SOI) =
is moving? or at certain intervals? another question is about the range =
of checking. According to the paper, seems like checking is done only =
for those entities within your SOI, however, to ensure Global =
Conneectivity (GC), it seems like it's possible you would connect to =
entities outside of your SOI, then will you check for those entities =
whether they're enterining someone else's SOI?)=20

Q3. A very important question is, is GC guaranteed to be maintained if =
every node keeps the "inside convex hull" property? I understand you =
seem to be thinking that is the case, however, has this been proven by =
either simulation or mathematicial analysis? (I'm very curious to this =
question, because I've also met with a similiar problem).=20

Q4. To ensure Local Awareness and Global Connectivity, entities need to =
connect to each other, however, are connections between entities =
uniquely determined, given their locations in the virtual world, or are =
there actually more than one possibility of these 'links' between =
entities? (I'm thinking the case when an entity is trying to ensure GC, =
the entities connections it end up doing, might not be done in a =
strictly deterministic manner, or is it purely deterministic?)

Q5. under what situation would SOI be enlarged? (the paper describes how =
it could be reduced, when there are too many to connect, what about =
enlargement?)=20

sorry for these long questions, I'd appreicate very much if you could =
answer them. :)

We've got a paper that'll appear in the NetGame 2004 workshop coming up =
in early Sept. also on P2P networked virtual environment. If you're =
interested, I'd be willing to forward a copy to you.

Thanks again and cheers! :)


Shun-Yun Hu