Service-Oriented Computing: Semantics, Processes, Agents August 2004 Aplicatii Web bazate pe semantica, agenti si servicii http://turing.cs.pub.ro/webs_08 Universitatea Politehnica Bucuresti Anul universitar 2008-2009, Master Adina Magda Florea © Singh & Huhns

Viziunea viitoare asupra WEB Service-Oriented Computing: Semantics, Processes, Agents August 2004 Viziunea viitoare asupra WEB Omniprezent Nu exista autoritate centrala Colectie de omponente eterogene si autonome Web semantic Calcul P2P Procese Web pragmatic © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Web – ce ar trebui Semantic Web - Tim Berners-Lee HTML – descrie detalii pt prezentare Necesita o reprezentare separata a continutului Semantica – cum reprezentam? Reprezentarea cunostintelor, IA, modele formale P2P programe active care pot comunica necesita semantica, de ex pt negociere flexibilitate Procese azi – static si pasiv gaseste si compune programe complexe procese de business vs servicii viziune orientata pe procese a serviciilor – standarde de modelare a procesului de business – extindere ale standardelor de servicii Web © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Web pragmatic Modele si tehnologii bazate pe servicii Web, semantica, agenti care pot fi utilizati pentru a crea sisteme informatice mari, deschise Web pragmatic Negociere: modelare semantica, interactiuni P2P, interactiuni multiple in procese de business Directii de dezvoltare: Automatizare: oameni, programe Marcare mai bogata Activitati mai bogate: Pasiv  Activ, Servicii  Procese Considerare context: semantica  intelegere mutuala  pragmatica © Singh & Huhns

Sematica pe Web oameni  masini  agenti Client-Server  P2P  Cooperativ Sintaxa  Semantica  Intelegere mutuala  Pragmatica si cunoastere Date  Servicii  Procese Viitorul serviciilor Web: focus pe organizare si societati Pragmatics (getting work done) - Workflows, BPEL4WS Distributed Cognition - Decisions and Plans Semantics and Understanding - Ontologies, OWL Syntax, Language, and Vocabulary Servicii Web curente: focus pe indivizi si grupuri mici

Evolutie sisteme: centralizat Service-Oriented Computing: Semantics, Processes, Agents August 2004 Evolutie sisteme: centralizat Terminal 3270 Terminal Terminal Terminal Terminal Mainframe Terminal Terminal Terminal Terminal Terminal Terminal © Singh & Huhns

Evolutie sisteme: Client-Server Service-Oriented Computing: Semantics, Processes, Agents August 2004 Evolutie sisteme: Client-Server Workstation Client PC Client PC Client PC Client E-Mail Server Web Server Database Server Master-Slave © Singh & Huhns

Evolutie sisteme: Peer-to-Peer Service-Oriented Computing: Semantics, Processes, Agents August 2004 Evolutie sisteme: Peer-to-Peer Application Application Application Application E-Mail System Web System Database System © Singh & Huhns

Evolutie sisteme: Cooperative Service-Oriented Computing: Semantics, Processes, Agents August 2004 Evolutie sisteme: Cooperative Application Agent Application Agent Application Agent Application Agent Agent Agent E-Mail System Agent Agent Database System Web System (Mediators, Proxies, Aides, Wrappers) © Singh & Huhns

Evolutie similara la nivelul retelelor Internet Intranet: retea privata la nivelul unei intreprinderi Extranet: retea privata limitata la anumite intreprinderi selectate Virtual Private Network (VPN): un mod de a realiza intranet sau extranet in Internet Internet computing sau servicii Web– toate aceste posibilitati

Sisteme deschise: caracteristici Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme deschise: caracteristici Componente autonome Componente eterogene Configuratia se modifica dinamic: comportare, arhitectura, implementare, interactiuni intra si ies © Singh & Huhns

Sisteme deschise si Web pragmatic Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme deschise si Web pragmatic Servicii Semantica Agenti © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 1. Servicii Web Definitii: O componenta a logicii de business accesibila prin Internet pe baza standerdelor deschise (Microsoft) Functii software incapsulate, slab interconectatae si care pot fi contractate si oferite prin protocoale standard pe Web (DestiCorp) Componente software slab conectate care interacioneaza intre ele dinamic pe baza tehnologiilor Internet standard (Gartner) O aplicatie software identificata de un URI a carei interfata poate fi definita, descrisa si descoperita de artefacte XML si care suporta interactiuni directe cu alte aplicatii software folosind mesaje bazate pe XML, pe baza protocoalelor Internet (W3C) © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Servicii Web Serviciile – o paradigma de programare care permite dezvoltarea metodelor de programare a sistemelor distribuite, deschise Programarea orientata pe servicii Eforturi de standardizare a serviciilor © Singh & Huhns

Evolutie servicii pe Web Generation Scope Technology Example First All Browser Any HTML page Second Programmatic Screen scraper Systematically generated HTML content Third Standardized Web services Formally described service Fourth Semantic Semantic Web services Semantically described service

Standardizare Schema preluata din Service-Oriented Computing: Semantics, Processes, Agents – Munindar P. Singh and Michael N. Huhns, Wiley, 2005

Service-Oriented Computing: Semantics, Processes, Agents August 2004 2 Semantica Reprezentarea cunostintelor Rationament Metode pt a construi descrieri de nivel inalt ale lumii care pot fi utilizate pt a dezvolta aplicatii complexe, inteligente Reprezentari bazate pe logica simbolica Alte reprezentari: reguli retele © Singh & Huhns

Logica de ordinul intai Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logica de ordinul intai Conceptualizare Sintaxa Semantica Interpretare Model Model – liniar sau structurat M |=S  Teoria modelului entailment - consecinta logica KB |=  Teoria demonstratiei axiome si reguli de inferenta KB |-i  © Singh & Huhns

Logica de ordinul intai Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logica de ordinul intai Decidabilitate Completitudine Consistenta Complexitatea calcului © Singh & Huhns

Logici de ordin superior Service-Oriented Computing: Semantics, Processes, Agents August 2004 PrL, PL Linear model Sentential logic of beliefs Uses beliefs atoms BA() Index PL with agents Other representations Situation calculus Adds states, actions Symbol level Modal logic Modal operators Structured models Knowledge level Temporal logic Modal operators for time Linear time Branching time Dynamic logic Modal operators for actions Logics of knowledge and belief Modal operators B and K Logici de ordin superior CTL logic Branching time and action BDI logic Adds agents, B, D, I © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logica propozitiilor LP – Limbajul logicii propozitionale  - multimea propozitiilor atomice Sin-1) a  implica a  LP Sin-2) p, q  LP implica pq  LP, q  LP M0 =<L> modelul LP L  - interpretare Sem-1) M0 |= a iff aL, unde a  Sem-2) M0 |= pq iff M0 |= p si M0 |= q Sem-3) M0 |= p iff M0 |=/ p p = A  B A - ploua q = A  B B – ia umbrela r = A  A A B A  B AB AA T T T T T T F F F T F T T F T F F T F T © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logica predicatelor Cunostinte despre existenta orbiectelor si relatiilor (x)(P(x)) (x)(P(x)) p = (x) young(x)  success(x) q = (x) young(x)  success(x) D = {Bill, Tom, Alice} M M |= p x young(x) success(x) M |=/ q Bill T T Tom F T Alice F F 22 © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logica modala LM – Limbajul logicii modale 2 operatori modali  p - p posibil adevarat  p - p necesar adevarat Sin-3) regulile din LP sunt in LM Sin-4) p  LP implica p, p  LM Lumi posibile Structura modelului – relatie binara de accesibilitate intre lumi M1 =<W, L, R> W – multime de lumi L:W  P() – multimea de formule adevarate intr-o lume, R  W X W  p p – ploua la Bucuresti  q q – maine rasare soarele © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sem-4) M1 |=W  iff L(w), where   Sem-5) M1 |=W pq iff M1 |=W p and M1 |=W q Sem-6) M1 |=W p iff M1 |=/W p Sem-7) M1 |=W  p iff (w': R(w,w')  M1 |=W' p) Sem-8) M1 |=W  p iff (w': R(w,w')  M1 |=W' p) in w0 ?  p, ? q, ? r ?  q Relatia de accesibilitate - reflexiva iff (w: (w,w)R)  p  p - seriala iff (w: (w': (w,w')R))  p   p - tranzitiva iff (w1,w2,w3: (w1,w2)R  (w2, w3)R  (w1,w3)R)  p    p - simetrica iff (w1,w2: (w1,w2)R  (w2,w1)R) p   p - euclidiana iff (w1,w2,w3: (w1,w2)R  (w1, w3)R  (w2,w3)R)  p   p w0 p, q, r w1 w2 p, q, r w3 p, q, r © Singh & Huhns

Sisteme bazate pe reguli Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe reguli Reguli reactive on eveniment if conditie then (executa) actiune Reguli de inferenta if anecedent then consecinta ciclul de inferenta inlanturie inainte inlantuire inapoi © Singh & Huhns

Sisteme bazate pe reguli Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe reguli © Singh & Huhns

Sisteme bazate pe reguli Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe reguli Jess – motor de inferenta bazat pe reguli scris in Java foloseste algoritmul RETE de identificare utilizeaza obiecte structurate si reguli (deftemplate automobil (slot producator) (slot model) (slot an (type INTEGER)) (multislot accesorii) (slot culoare (default argintie))) (defrule vopseste-auto ?fact <- (automobil (an ?y) (culoare ?c)) (test (neq ?c argintiu) => (modify ?fact (culoare argintiu)) (printout t “Revopsit “ ?y “in culoare argintie” crlf) © Singh & Huhns

Sisteme bazate pe reguli Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe reguli Semantic Web Rule Language SWRL Limbaj de reprezentare a regulilor pe Web si combinarea lor cu ontologii standard Extinde axiomee OWL cu clauze Horn Porneste de la RuleML © Singh & Huhns

Sisteme bazate pe obiecte structurate Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe obiecte structurate Retele semantice Relatie individual-generic, sau instanta-clasa, notata ISA (prescurtare de la IS A). Relatia generic-generic, sau subclasa-clasa, notata AKO (prescurtare de la A Kind Of). Obicete particulare / obiecte generice Sloturi Inferente specifice © Singh & Huhns

Sisteme bazate pe obiecte structurate Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme bazate pe obiecte structurate KL-ONE Introduce multe notiuni din DL concepte, roluri, restrictie valoare, restrictie numerica Inferente: subsumare, clasificare Completitudine Complexitate © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logici de descriere O familie de DL Concept – expresie intr-un limbaj DL care reprezinta o multime de indivizi Terminologie – o structura ierarhica construita pentru a oferi o reprezentare intensionala a domeniului de interes Modelul formal OWL © Singh & Huhns

Logici de descriere - arhitectura Service-Oriented Computing: Semantics, Processes, Agents August 2004 Logici de descriere - arhitectura Man  hasChild.Female  hasChild.Male  hasChild.(Rich  Happy) Knowledge Base Tbox (schema) Man ´ Human u Male Happy-Father ´ Man u 9 has-child Female u … Interface Inference System Abox (data) John : Happy-Father hJohn, Maryi : has-child © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 3 Agenti “De cele mai multe ori, oamenii folosesc termenul agent pentru a referi o etitate care functioneaza permanent si autonom intr-un mediu in care exsita alte procese si/sau alti agenti” (Shoham, 1993) “Un agent este o entitate care percepe mediul in care se afla si actioneaza asupra acestuia” (Russell, 1997) “Agentii inteligenti indeplinesc 3 functii: percep conditiile dinamice din mediu, actioneaza pentru a modifica aceste conditii, si rationeaza pentru a interpreta perceptii, a rezolva probleme, a face inferente, si a stabili ce actiuni sa execute. (Hayes-Roth 1995)” “Agentii inteligenti sunt entitati software care executa anumite operatii pentru utilizator sau pentru un alt program, cu un anumit grad de independenta sau autonomie si utilizeaza cunostinte si reprezentarea scopurilor utlizatorului” (the IBM Agent) © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Agenti “Agent = un sistem (software sau hardware) cu urmatoarele proprietati: autonomie – agentii opereaza fara interventai directa a utilizatorui si au un anumit control asupra actiunilor si starilor lor; Actiune autonoma flexibila reactivitate: agentii percep mediul si reactioneaza corespunzator al schimbarile din acesta; pro-activitate: agentii, pe langa reactia la schimbarile din mediu, sunt capabili sa urmareasca executia scopurilor si sa actioneze independent; abilitati sociale – agentii interactioneaza cu alti agenti sau cu utilizatorul pe baza unui limbaj de comunicare. (Wooldridge and Jennings) © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Agenti 2 directii de definitie Definirea unui agent izolat Definirea agentilor in colectivitate  dimensiune sociala  SMA 2 tipuri de definitii Nu neaparat agenti inteligenti Include o comportare tipica IA  agenti inteligenti Caracteristici agenti Actioneaza pentru un utilizator sau un program Autonomie Percepe mediul si actioneaza asupra lui reactiv Actiuni pro-active goal-directed behavior vs reactive behaviour? Caracter social Functionare continua (persistent software) mobilitate ? inteligenta? Scopuri, rationalitate Rationament, luarea deciziilor cognitiv Invatare/adaptare Interactiune cu alti agenti – dimensiune sociala Alte moduri de a realiza inteligenta? © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Mediul unui agent Agent Proprietatile mediului - Accesibil vs inaccesibil - Determinist vs nondeterminist - Static vs dinamic - Discret/continuu - Contine sau nu alti agenti Sensor intrare Actiune iesire Mediu © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme multi-agent Mai multi agenti intr-un mediu comun Mediu Zona de influenta Interactiuni © Singh & Huhns

Service-Oriented Computing: Semantics, Processes, Agents August 2004 Sisteme multi-agent Interactiuni intre agenti - nivel inalt Interactiuni pentru- coordonare - comunicare - organizare Coordonare  motivati colectiv  motivati individual scopuri proprii / indiferenta scopuri proprii / competitie pentru resurse scopuri proprii si contradictorii / competitie pentru resurse scopuri proprii / coalitii © Singh & Huhns