Partecipazione in Ambienti Virtuali e Giochi

Transcript

1 Partecipazione in Ambienti Virtuali e Giochi Partecipare ad una Vita Alternativa dentro un Ambiente Sintetico Stefano Cacciaguerra (scacciag@cs.unibo.it) 1

2 Contenuti Introduzione Esempi Ambienti Virtuali Come Gestire la Partecipazione in essi 2

3 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 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 d.c. L. Carroll scrive Alice nel Paese delle Meraviglie. Prende forma l idea di un viaggio paradossale nei territori della fantasia 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 d.c. D. Arneson e G. Gygax creano il primo sistema di regole per Dungeons&Dragons. Il primo gioco di ruolo moderno. 3

4 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 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 abbonati 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

5 Domande Chi comprarebbe un isola che non c è per 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

6 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 Warcraft Oltre 5 milioni di abbonati Project Entropia Turnover di dollari in gennaio 2005 Second Life Centinaia di negozi dalla Ferrari all i-pod 6

7 Ultima 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. 7

8 Scenario 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 8

9 Any-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. 9

10 Problems 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. 10

11 Formalizzation 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. 11

12 Movements 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. 12

13 Effects 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 13

14 Classes 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 14

15 Design 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. 15

16 Interactivity 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 16

17 Coherence 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 reproposes the actions of its player by reproducing her/his behavior. 17

18 Esempio Agente A gioca autonomamente Agente A gioca al posto dell utente Sistema complesso simulato timeline 18

19 Animazione 19

20 Equity 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! 20

21 The Participatory Framework It supports interaction management between players and their avatars on unreliable networks using a turn-based multiagent system. It enhances the TCP/IP stack implementing a playingsession 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. 21

22 The Participatory Framework Participatory components Dynamic load-balancing Agent Discovery System Agent Discovery System Client Client SPF APF Agent Communication Communication Server Server load updater Simulation Simulation Engine Engine load balancer World Model SimView Mobile side Game side 22

23 How 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. 23

24 Game 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 24

25 Mobile 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 playingsession with its own avatar. 25

26 Conclusions 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. 26

27 Future 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. 27

28 Riferimenti Ambienti Virtuali e Giochi Vivere una Vita Alternativa dentro un Ambiente Sintetico Vite Parallele Project Entropia Second Life World of Warcraft Hive7 28

29 Riferimenti 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 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 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 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 S. Cacciaguerra, M. Roccetti & P. Salomoni, Multimedia Entertainment Applications, in Encyclopedia of Multimedia, ((B. Furht Ed.), Springer, 2005, , 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, , 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 To appear S. Cacciaguerra e M. Roffilli, The Artificial Intelligence promotes Internet communities. 29