1. Service-Oriented Computing: Semantics, Processes, Agents
August 2004
Aplicatii Web bazate pe semantica, agenti si servicii
Universitatea Politehnica Bucuresti Anul universitar , Master Adina Magda Florea
© Singh & Huhns

2. 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

3. 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

4. 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

5. 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

6. 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

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

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

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

10. 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

11. 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

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

13. 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

14. 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

15. 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

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

17. 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

18. 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

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

20. 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

21. 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

22. 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

24. 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

25. 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

26. 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

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

28. 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

29. 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

30. 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

31. 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

32. 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

33. 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

34. 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

35. 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

36. 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

37. 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

38. 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

39. 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