Partecipazione in Ambienti Virtuali e Giochi - Partecipare ad una Vita Alternativa dentro un Ambiente Sintetico
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Partecipazione in Ambienti
Virtuali e Giochi
Partecipare ad una Vita Alternativa dentro
un Ambiente Sintetico
Stefano Cacciaguerra (scacciag@cs.unibo.it)
1
Contenuti
Introduzione
Esempi
Ambienti Virtuali
Come Gestire la Partecipazione in essi
2
Introduzione
2500 a.c. Nella città sumera di Ur nasce il Gioco Reale di Ur. Il primo
gioco da tavolo in cui il giocatore è rappresentato da una pedina.
1664 d.c. Un certo C. Weikmann inventa Konigsspiel il gioco del re. Un
esercito di 30 figurine preso dagli scacchi e antenate dei soldatini
per ciascuno dei 14 diversi ruoli di combattimento simulando le
lotte del potere dell’epoca.
1865 d.c. L. Carroll scrive Alice nel Paese delle Meraviglie. Prende
forma l’idea di un viaggio paradossale nei territori della fantasia.
1969 d.c. Per facilitare la comunicazione tra poli universitari in america R.
Talyor dell’agenzia Arpa collega 4 calcolatori di università
differenti. Arpanet sarà la madre di Internet.
1972 d.c. D. Arneson e G. Gygax creano il primo sistema di regole per
Dungeons&Dragons. Il primo gioco di ruolo moderno.
3
Introduzione
1978 d.c. Nell’Università di Essex, in Inghilterra, fa la comparsa il primo
Multi-User Dungeon (MUD), ideato da R. Trubshaw. È ancora
un gioco fatto di solo testo che permette agli utilizzatori di
spostarsi in zone virtuali diverse e di dialogare tra loro.
1997 d.c. I Mondi Virtuali ed i Massive Multiplayer Online Role Play
Games (MMORPG) diventano popolari negli USA. Il più
famoso è Ultima Online di R. Garriot, una simulazione della vita
medioevale in 3D. Il gioco conta 160.000 abbonati.
2005 d.c. World of Warcraft, un mondo virtuale di ambientazione
fantasy ispirato ad un saga di Massive Multiplayer Online Real
Time Strategy games (MMORTS) totalizza 5 milioni di
abbonati.
Tratto dall’articolo Vite Parallele apparso sul
mensile Quark, marzo 2006.
4
Domande
Chi comprarebbe un’isola che non c’è per 26500 dollari sul pianeta
entropia?
Chi comprerebbe un paio di nike o di levi’s 501 per la propria
controparte artificiale?
Chi ucciderebbe (per davvero!) un concorrente rivale dopo che ti ha
rubato la preziosa spada magica?
Domande assurde, eppure trovano la stessa risposta!
Un partecipante ad un Ambiente Virtuale
5
Gli AV Costituiscono una Realtà
Gli Ambienti Virtuali (AV) stanno entrando prepotentemente nelle nostre vite
tanto da costituire una seconda chance per molti umani.
Gli AV hanno un’economia, un governo, una valuta. Migliaia di Abitanti vi ci
nascono e vi ci muoiono.
Sono mondi di fantasia accessibili via web.
World of Project Second
Warcraft Entropia Life
Oltre 5 milioni di Turnover di 16.350.000 Centinaia di negozi
abbonati dollari in gennaio 2005 dalla Ferrari all’i-Pod
66Ultima Ora
Il mondo virtuale di Hive7 è stato interamente realizzato con
tecnologia AJAX, da molti considerata l'ossatura principale del
cosiddetto Web 2.0.
Un prototipo di metaverso, termine della letteratura cyberpunk che
indica un mondo digitale accessibile tramite interfaccia telematica.
7Scenario
Wireless hotspots in the World are increasing the
availability of network connectivity.
Nintendo, Sony and Nokia are competing in the
wireless handheld entertainment market:
● Dual Screen,
● PSP
● N-Gage.
Mobile massive multi-player games are
investigated also by the scientific community
8Any-time, Any-place
Traditional multi-player gaming will take on new hybrid wireless /
wired forms supporting any-time and any-place management of a
playing-session.
9Problems
What happens extending wired Internet through wireless to
provide gaming on mobile devices:
● When a mobile gamer needs to participate in an Internet game, but is
far from the nearest access point?
● Or when the mobile gamer is moving from one access point to
another?
Handovers, transmission errors and temporary link outages
cause delays and packet losses.
10Formalizzation and Solution
A user may not be able to send or may send with a
significant delay actions to the game system, losing some
turns of the match.
these have fewer chances to win the match.
A participatory framework that handles communication when
network faults occur, while guaranteeing interactivity,
coherence and equity to all gamers,
to ensure a good playability.
11Movements Cause Interruptions
Short period interruption are caused by:
● vertical or horizontal handovers,
● transmission errors and
● temporary link outages.
Long period interruptions by:
● a disconnection due to failed handovers,
● extended link outages and
● application shutdowns.
12Effects and Tricks
Interruptions disdavantage Players:
● making them lose a turn, or even worse
● causing them to lose a match because they had been
disconnected from the system!
The classes of mobile games use specific tricks to limit
lags and packet losses:
● Multi-Solo-Player
● Turn-Based
● Endless
● Slow Evolution
13Classes of Mobile Games
Multi-Solo-Player
● As information is exchanged with the server at the beginning and the
end of each match, problem occur only during non-critical phases.
Turn-Based
● Round-Robin: All players can only look the action whose is playing
and wait for their next turn.
● Simultaneous Movement: The game system waits for actions, played
independently from all gamers, resolves the turn and returns the result
to all participants.
Endless
● MMORPG: to prevent obsessive players from taking a large advantage
over casual ones, there is a set limit to the number of actions per time.
Slow Evolution
● MMORTS: entities perform a specified behaviors that do not need to a
continuous management
14Design Issues
The game system stays on the wired Internet while users participate
in it from a graphical shell on a mobile device.
A framework able to handle the communication on both sides when
mobility problems occur while guaranteeing interactivity,
coherence and equity for all gamers.
● On the mobile side: the framework decides whether to wait for another
ack from the game system or to reconnect it.
● On the game side: the framework is able to detect if any shell had some
problems. If so, it takes control of the player’s avatar until the problems
are solved.
15Interactivity
The latency between action generation on a mobile device
and event visualization in the shell.
The game system maintains the interactivity under a
sensorial perceptivity threshold, waiting for users’ action up
to a timeout.
The velocity of the evolution of the game system becomes
independent from the interruption of a single players
16Coherence
The uniformity of the evolution of the game rather than to
the behavior of each user.
To take control of users’ avatars reproducing the strategy of
all players by monitoring them at the game side to recognize
the typical patterns of their behaviors.
When a timeout expires, a mimicking mechanism re-
proposes the actions of its player by reproducing her/his
behavior.
17Esempio
Agente A gioca Agente A gioca al
autonomamente posto dell’utente
Sistema
complesso
simulato
timeline
18Animazione
19Equity
Interactivity + Coherence also guarantees equity to all
players.
If a player was not able to send actions to its avatar,
something else controls it for her/him.
Not all players will take the same number of actions at the end
of the match, but at least the number of events is the same
for each avatar!
20The Participatory Framework
It supports interaction management between players and their
avatars on unreliable networks using a turn-based multi-
agent system.
It enhances the TCP/IP stack implementing a playing-
session layer between the transport and application levels to
handle the communication between a user and her/his avatar.
each agent (avatars included) must act once in each turn its
duration is shorter than the sensorial perceptivity threshold.
21The Participatory Framework
Participatory components
Dynamic load-balancing
Agent Discovery System
Agent
Discovery
System
Client
Client SPF APF Agent
Agent Communication Simulation
Server
Communication Engine
Simulation World
Server Engine Model
load load
updater balancer
SimView
Mobile side Game side
22How to Solve Problems
In a short period interruption:
PF guarantees the game evolution by controlling the slowed
avatars according to theirs behavioral models after a time equal
to the perceptivity threshold.
In a long period interruption:
PF tries to recovery the playing-session while an appropriate
behavioral model generates actions for avatar reproducing the
strategy of its player.
23Game Side (Avatar PF)
APF checks for a TCP connection from its SPF.
If the connection is active, it controls:
● If the Action timeout is exceeded, it turns to a behavioral
model to control the avatar for the player.
● If the number of consecutive action timeouts exceeds a
maximum value (i.e. the TCP timeout), it shuts down the
connection
Else it suspends in the listening phase ready to recovery the
playing-session.
● In the meantime, it takes the control the avatar through the
behavioral model
24Mobile Side (Shell PF)
If its agent is reachable, it waits for a request action event from
its APF within a Action timeout
● If the timeout expires, it buffers the last action produced by
the player, waiting for the next Request Action event to arrive.
● After a time equal to Action timeout multiplied by a constant
(i.e. the TCP timeout) has passed without receiving any
Request Action event from the APF, it shuts down the
connection.
Else a new connection is necessary to resume the playing-
session with its own avatar.
25Conclusions
To prevent mobile gamers from unpleasant experiences on
unreliable networks, we enhance the stack TCP/IP
implementing a playing-session level through a PF.
Coupling the playing-session management with the
reproduction of the players’ behavior improves the equity of
the system and the speed of evolution of the game.
We combined PF with SPADES offering also an environment
for further studies.
26Future Works
We are not sure whether the suggested timeout policies are the
best ones
with this in mind, we are planning another campaign to
catalogue them.
Demonstrating the efficacy of the PF at the game level:
taking the same number of events (for each avatar)
promotes the same chance to win.
27Riferimenti
Ambienti Virtuali e Giochi “Vivere una Vita Alternativa dentro un Ambiente Sintetico”
http://www.cs.unibo.it/~scacciag/home_files/teach/ambientivirtuali.pdf
Vite Parallele
http://www.videoludica.com/news.php?news=201
Project Entropia
http://www.entropiauniverse.com
Second Life
http://secondlife.com
World of Warcraft
http://www.worldofwarcraft.com
Hive7
http://www.hive7.com/
28Riferimenti
S. Cacciaguerra, S. Mirri, P. Salomoni & M. Pracucci Wandering About the City, Multi-Playing a Game, in Proc. the 2nd IEEE
International Workshop on Networking Issues in Multimedia Entertainment , Las Vegas (USA), January 2006.
S. Cacciaguerra, C. Cagneschi & R. Fabbri The Architectonical Design of Virtual Environments Fuels a new Form of the
WWW, in Proc. European Simulation and Modelling Conference 2005, Porto (Portugal), October 2005.
S. Cacciaguerra, M. Roffilli Agent-based participatory simulation activities for the emergence of complex social behaviours, in
Proc. of AISB05, Social Intelligence and Interaction in Animals, Robots and Agents, Hatfield, (England), April 2005.
S. Cacciaguerra, S. Mirri, P. Salomoni & M. Baldassarri Almost Blue: The Design of a Cooperative Game by Integrating
Accessible Interaction, in Proc. of Euromedia 2005 Toulouse, (France), April 2005.
S. Cacciaguerra , M. Roccetti & P. Salomoni, Multimedia Entertainment Applications, in Encyclopedia of Multimedia, ((B.
Furht Ed.), Springer, 2005, 510-518, included also "Digital Cinema", "In-home, In-car, In-flight Entertainment", "Interactive
Story Telling".
S. Ferretti, M. Roccetti & P. Salomoni On-line Gaming, in Encyclopedia of Multimedia, (B. Furht Ed.), Springer, January
2006, 653-660, included also “Dead Reckoning”, “Fairness in Online Games”, “Game Accessibility”, “Game Event
Synchronization”.
K. Mitchell, D. McCaffery, G. Metaxas, J. Finney, S. Schmid, A. Scott, “Six in the city: introducing Real Tournament - a
mobile IPv6 based context-aware multiplayer game,” Proc. of the 2nd workshop on Network and system support for games,
ACM press, 2003, pp. 91-100.
To appear
S. Cacciaguerra e M. Roffilli, The Artificial Intelligence promotes Internet communities.
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