TI LIU N THI MN SEMANTIC WEB

L thuyt1. Web ng ngha l g?a. nh ngha: Web ng ngha l s m rng ca Web hin ti m trong thng tin c nh ngha r rng sao cho con ngi v my tnh c th lm vic vi nhau mt cch hiu qu.Mc tiu ca Web ng ngha l pht trin cc chun chung v cng ngh, ci tin Web hin ti bng cch thm vo mt lp ng ngha my tnh c th hiu c thng tin Web nhiu hn, tng cng kt xut thng tin mt cch t ng, tch hp d liu.Vy SW l mt mng li cc thng tin ton cu c lin kt theo mt cch thc my tnh d dng x l. C th hiu n gin n l mt cch trnh by d liu c hiu qu trn mng ton cu. SW c kh nng lm vic vi d liu, iu ny m ra mt lp cc ng dng mi trn nn Web ng ngha.SW ha hn cung cp mt m hnh lin kt nhng ngun thng tin khc nhau chng hn nh nhng trang Web, cc CSDL hay ngay c lung d liu v thng tin trong cuc sng hng ngy. Do cc ng dng c thit k da trn cc khi nim cp v s dng cc thng tin c th x l c bng my tnh, to ng lc ln cho vic pht trin ca mt th h cc cng c v cc ng dng Web mi.b. Bn cht ca SW. D liu my tnh c th c c: SW l mt vin cnh, tng l d liu c nh ngha, lin kt trn Web theo cch ny c th t ng ha, kt hp v s dng li d liu thng qua cc ng dng khc nhau ch khng phi ch cho mc ch hin th. Cc tc t thng minh: Mc ch ca SW l trnh din Web cho my c kh nng c, t cho php cc chng trnh thng minh truy hi v x l thng tin tch hp. CSDL phn tn: SW linh hot c kh nng th hin tt c CSDL v cc quy tc logic lin kt chng li vi nhau to thnh mt gi tr gia tng. Ch thch tt hn: tng ca SW cung cp cho Web hin ti cc ch thch dng my tnh c th x l c v lin kt chng li vi nhau. Ci thin chc nng tm kim: C th truy cp ti nguyn Web thng qua ni ung thay cho t kha nh trong Web hin ti. Mc ch chnh l xy dng mt ch mc c cu trc cho trang Web. Cc dch v Web: SW cung cp truy cp khng ch nhng ti liu tnh su tp thng tin h dng m cn cho cc dch v cung cp cc chc nng hu ch khc.c. Cu trc Web ng ngha. Tng Unicode & URI: nhm bo m vic s dng tp k t quc t v cung cp ln nh danh cc ti nguyn trong Web ng ngha. Tng XML: cng vi nh ngha v kg tn v l bo m rng chng ta c th tch hp cc nh ngha SW vi cc chun khc da trn XML Tng RDF v RDFS: to cc pht biu m t cc i tng vi nhng t vng v nh ngha URI, cc i tng c th tham chiu n nhng t vng v nh ngha URI trn. y l lp m chng ta c th gn cc kiu (type) cho cc ti nguyn v lin kt. Ontology Vocabulary: b t vng c xd trn c s tng RDF v RDFS, cho php th hin ng ngha hnh thc, nh ngha mi lin h gia cc khi nim vi nhau Tng Logic: xy dng tp lut, xem nh l c s lut trn SW h tr cho qu trnh suy din. Tng Proof: CM suy din ca h thng bng cch lin kt cc s kin. Tng Trust: m bo tnh tin cy ca cc ng dng trn SW gip ng dng quyt nh nn hay khng nn tin tng ti nguyn. Tng Digital Signature: ch k in t, dng xc nh ch th ca ti nguyn.2. RDFa. RDF l g RDF l ngn ng m t thng tin v ti nguyn trn Web. RDF c bit dng m t siu d liu v ti nguyn Web nh tiu , tc gi, ngy thng to lp v chnh sa Web, thng tin bn quyn v cc thng tin ng k v ti liu Web hoc c th c dng ln k hoch cho mt ti nguyn chia s. RDF s dng cc URI dng nh danh ngun ti nguyn Web v cc thuc tnh m t cc ngun ti nguynMc d RDF c gi l ngn ng nhng thc cht RDF l mt m hnh d liu. D nhin, mt m hnh d liu tru tng cn mt c php c th din t v RDF din t da vo c php XML c gi l RDF/XML. Bng cch s dng XML, thng tin trong RDF c th d dng trao i gia cc my tnh khc nhau, s dng cc h iu hnh khc nhau v cc ngn ng ng dng khc nhau. Tuy nhin c php ca RDF khng nht thit phi da vo XML m c nhiu cch trnh by c php khc ca RDF.RDF l khung ng dng m t ti nguyn x l siu d liu trn Web, cung cp tnh lin thng gia cc ng dng nhm trao i thng tin m my tnh c th x l c, c ch m t ti nguyn m gi s cc d liu ca ti nguyn khng thuc mt min ng dng no htb. Cc thnh phn c bn ca RDF Ti nguynTi nguyn (Resource) l mt i tng, mt ci (thing) g m chng ta co th cp n. Chng hn nh ti nguyn c th l cc tc gi, nhng cun sch, nh xut bn, a im, con ngi, khch sn, phng, cc truy vn tm kim v.vMi ti nguyn c mt URI. Mt URI c th l mt URL (Uniform Resource Locator, hay a ch WEB hay mt loi nh dnh duy nht no ; lu rng mt nh dng khng c ngha l c th truy nhp n ti nguynCc lc URI c nh ngha khng ch cho cc a ch Web m cn cho cc i tng a dng khc nh cc s in thoi, nhng s ISBN, v cc a ch a l. Thc t c cc tho lun di v tnh cht ca URI hay nh cc cu hi c tnh cht trit l (chng hn cc nh danh duy nht no l hp l s dng cho mt con ngi). Mt cch tng qut, chng ta gi s rng mt URI l mt nh danh cho mt ti nguyn Web. Thuc tnh.Cc thuc tnh(Property) l cc dng ti nguyn c bit, chng m t cc mi quan h gia cc ti nguyn, v d nh written by, age, title, v.vCc thuc tnh trong RDF cng c xc nh bi cc URI v trong thc t l URL tng v s dng URI xc nh cc thing v quan h gia chng l rt quan trng. S la chn ny cho chng ta mt c ch nh tn duy nht, ph dng v ton cu. Pht biu.Mt pht biu (Statement) l khng nh ca cc thuc tnh i vi cc ti nguyn. Mt pht biu l mt b ba cha mt ti nguyn, mt thuc tnh (property) v mt gi tr. Gi tr c th l cc ti nguyn hoc l cc literal. Cc literal l cc gi tr nguyn t (chui).c. M hnh d liu RDF nh nghaMt m hnh c bn ca RDF gm ba i tng sau: Ti nguyn (Resources): l tt c nhng g c m t bng biu thc RDF. N c th l mt trang Web, mt phn ca trang Web hay mt tp cc trang Web. Thuc tnh (Properties): thuc tnh, c tnh, hoc quan h dng m t tnh cht ca ti nguyn. Gi tr (Value): l gi tr c gn cho thuc tnh.M hnh RDF m t cc ti nguyn thng qua cc pht biu (statements), mi pht biu gm ba thnh phn sau: Ch th (Subject): a ch hay v tr ti nguyn mun m t, c xc nh bi URI. V t/thuc tnh (Predicate): xc nh tnh cht ca ti nguyn, cng c xc nh bi URI. i tng (Object): ni dung gn cho thuc tnh, c th l ti nguyn hoc gi tr literal. B ba RDFMi mt pht biu (ch th, v t/thuc tnh, i tng) cn gi l mt b ba (triple).V d: Xt pht biu sau:http://www.example.org/index.html has a creator whose value is John Smith.Pht biu c phn ra thnh cc thnh phn sau: Ch th (Subject)http://www.example.org/index.html V t/thuc tnh (Predicate) http://purl.org/dc/elements/1.1/creator i tng (Object):John SmithChng ta bit URI dng m t ti nguyn trn Web, chon en pht biu trn v phi dng t creator v John Smith, ta s dng URI http://purl.org/dc/elements/1.1/creator v http://www.example.org/staffid/85740 m t cho tng khi nim trn. Pht biu trn c biu din di dng mt b ba nh sau:

th RDF th RDF l mt th c hng v nh nhn, l phng php mc nh m t cc m hnh d liu RDF vi hai l do: Th nht, cc th rt d hiu v khng b nhm ln gia ch th, thuc tnh ca ch th v gi tr ca thuc tnh. Ngoi ra, khng tn ti s nhp nhng v cc pht biu ngay c khi tn ti bn trong mt m hnh d liu RDF phc tp.Th hai, s dng th RDF l k thut m t mc nh, l c cc m hnh d liu RDF ch c th biu din bng cc th RDF m khng phi trong RDF/XML.Mt b ba cn c th m t di dng nt cung nt. Hng ca th rt quan trng. Cung ca th lun bt u t ch th n i tng.Tp cc b hp li to thnh th RDF (RDF Graph). Cc nt trong th c th l cc ch th v i tng trong b ba RDF v cc cung trong th c th l cc v t, v c th nhn cc gi tr URI, nt trng hoc cc literal.

Ch thi tngV t/thuc tnh

Hnh 1.1. Mi quan h gia cc thnh phn trong b ba RDFV d: Vi pht biu trn ta c th m hnh ha li nh sau:

Hnh 1.2: M t pht biu n gin bng thV d: Ta thm cc pht biu sau cho cng mt ch thhttp://www.example.org/index.html has a creation-date whose value is August 16, 1999.http://www.example.org/index.html has a language whose value is English.c biu din di dng th sau:

Hnh 1.3: Biu din cho nhiu pht biu c cng subjectM hnh trn ch ra rng cc i tng trong pht biu RDF c th l mt URI hoc cng c th l mt gi tr literal. hnh trn ta dng hnh oval biu din mt ti nguyn l mt URI v dng hnh ch nht biu din mt ti nguyn l mt gi tr literal.1.1.1.1. RDF Literal.Literal c s dng biu din cc gi tr nh con s, ngy thng, chuiBt c ci g c th biu din bi mt gi tr literal cng c th c biu din di dng mt URI. Mt literal c th l i tng ca mt pht biu nhng khng th l ch th hay l thuc tnh.Literal c hai kiu sau: literal thng (plain) hay literal c kiu: Mt literal thng l mt chui c kt hp vi mt th XML bt k. Trong ngn ng t nhin ta c th gi l mt kiu text.V d

Hnh 1.4: Gi tr literal biu din cho tui ca John SmithGi tr 27 y ch l mt chui gm 2 k t 2 v 7. Nhng nu ta mun biu din n l mt con s, mt s nguyn th phi dng kiu literal c kiu. Mt literal c kiu c hnh thnh bng cch kt hp mt chui vi mt nh danh URI biu din mt kiu d liu c bit no . Kt qu tr v l mt nt trong th tng t nh kiu literal. Kiu gi tr c biu din literal c kiu s c nh x n kiu gi tr c bit m ta khai bo thng qua URI. v d trn, khi mun biu din tui ca John l mt kiu s nguyn th ta s c cch khai bo nh sau: Ch th (Subject)http://www.example.org/staffid/85740V t/thuc tnh (Predicate) http://www.example.org/terms/agei tng (Object):27< http://www.w3.org/2001/XMLSchema#integer>V c biu din thnh th nh sau:http://www.example.org/staffid/8574027 http://example.org/terms/age

Hnh 1.5: Literal c kiu biu din cho tui ng John Smith

3. Ontologya. nh ngha.Ontology l s hiu bit v domain no . Chia s nhau v s vt, hin tng c th trao i vi nhau. Cc ngn ng Ontology biu din tri thc chia s cho cc ng dng s dng c vi nhau. Ontology l mt c t tng minh, mang tnh hnh thc ca s khi nim ha c th chia s c bng cch xc nh cc khi nim lin quan ca hin tng . y tng minh c ngha l cc khi nim c s dng v cc rng buc trn chng c nh ngha r rng c v hiu Ontology. Chia s phn nh quan im rng mt Ontology nm bt tri thc c chp nhn bi mt nhm ngi.Ontology l mt thut ng c mn t trit hc, cp n ngnh khoa hc m t cc loi thc th trong th gii thc v chng lin h vi nhau nh th no. Trong W3C, mt Ontology cung cp cc m t cho cc phn t sau: Cc lp trong mt lnh vc xc nh Cc quan h gia cc lp Cc thuc tnh ca cc lp .Ontology gm c: Cc khi nim biu din thng qua lp v chng trnh phn lp ca cc lp cha cc php th hin. Thuc tnh gm c s dng t gc ca tr tu nhn to l Roles &Slots. Tin , quan h gia cc lp: K tha, rng buc trong tp thuc tnh, tnh cht ca thuc tnh (i xng, ko theo). Tc v suy din:+ Phn tch ca Ontology v phn lp cc khi nim+ Pht hin lp ny c bao nhiu lp khc.+ Kim tra tnh nht qun bn trong Ontology.b. Phng php xy dng OntologyBc 1: Xc nh mc ch: xc nh mc tiu s dng ca OntologyBc 2: Xy dng Ontology: chia thnh 3 bci. Xc nh cc khi nim v cc mi quan h chnh trong lnh vc quan tm. To cc nh ngha cho cc khi nim, cc mi quan h v xc nh cc thut ng tham chiu n chngii. M ha: biu din tri thc c bc (i) trong mt ngn ng hnh thc no .iii. Tch hp, hp nht cc Ontology ang tn ti: thit lp cc nh x khc nhau gia hai Ontology, do gi c cc Ontology ban u v ha nhp vi cc Ontology vi mc ch to ra mt Ontology duy nht t cc Ontology ban u. C th xem nh x gia cc Ontology l tp cc quy tc vit li kt hp cc thut ng v cc biu t c nh ngha trong mt Ontology ngun vi cc thut ng v cc biu t ca Ontology chBc 3: nh gi: thit lp mt nh gi v cc Ontology vi mt khung gm cc xc nh yu cu.Bc 4: Lp ti liu: Lp ti liu Ontology theo phn loi v mc ch.

Bi tp : Ngn ng truy vn SPARQL1. C php ca tng qut v cc khi nim c bnD liu:

"SPARQL Tutorial" .Truy vn:SELECT ?titleWHERE{ ?title}Kt qu truy vn:

Title

SPARQL Tutorial

2. Cho d liu nh sau: @prefix dc: .@prefix : .@prefix ns: .

:book1 dc:title "SPARQL Tutorial" . :book1 ns:price 42 .:book2 dc:title "The Semantic web" . :book2 ns:price 23 .

Truy vn: Khng c OPTIONALPREFIX dc: PREFIX ns: SELECT ?title ?priceWHERE { ?x ns:price ?price . FILTER (?price < 30) . ?x dc:title ?title . }Kt qu:titleprice

"The Semantic web"23

Bng cch rng buc bin price, ch c book2 thch hp vi truy vn v c mt gii hn da vo ga tr c php ca price.

Trng hp c OPTIONAL, kt qu truy vn:PREFIX dc: PREFIX ns: SELECT ?title ?priceWHERE { ?x dc:title ?title .OPTIONAL { ?x ns:price ?price . FILTER (?price < 30) } }titleprice

"SPARQL Tutorial"

"The Semantic web"23

Khng c gi c no cho cun sch vi ta SPARQL v mu th ty chn khng dn n mt li gii bao gm bin price.Hai th sau y s c s dng trong nhng v d:# Named graph: http://example.org/foaf/aliceFoaf@prefix foaf: .@prefix rdf: .@prefix rdfs: .

_:a foaf:name "Alice" ._:a foaf:mbox ._:a foaf:knows _:b ._:b foaf:name "Bob" ._:b foaf:mbox ._:b foaf:nick "Bobby" ._:b rdfs:seeAlso .

rdf:type foaf:PersonalProfileDocument .

# Named graph: http://example.org/foaf/bobFoaf@prefix foaf: .@prefix rdf: .@prefix rdfs: .

_:z foaf:mbox ._:z rdfs:seeAlso ._:z foaf:nick "Robert" .

rdf:type foaf:PersonalProfileDocument .Truy cp tn th.Truy vn bn di kt hp mu th da trn mi th c tn trong dataset v a ra nhng li gii m c bin src rng buc ti IRI ca th kt hp.PREFIX foaf: SELECT ?src ?bobNickWHERE { GRAPH ?src { ?x foaf:mbox . ?x foaf:nick ?bobNick } }Kt qu truy vn cho ta tn ca nhng th m thng tiin c tm thy v gi tr cho nick ca Bob:srcbobNick

"Bobby"

"Robert"

D liu:@prefix foaf: .

_:a foaf:name "Johnny Lee Outlaw" ._:a foaf:mbox ._:b foaf:name "Peter Goodguy" ._:b foaf:mbox . Truy vn:PREFIX foaf: SELECT ?name ?mboxWHERE { ?x foaf:name ?name . ?x foaf:mbox ?mbox } Kt qu truy vn:namembox

"Johnny Lee Outlaw"

"Peter Goodguy"

Kt hp kiu OPTIONAL.Nhng thnh phn ty chn ca mu th c th c xc nh v mt c php vi t kha OPTIONAL c p dng vo mt kiu th:D liu:pattern OPTIONAL { pattern }d liu:@prefix foaf: .@prefix rdf: .

_:a rdf:type foaf:Person ._:a foaf:name "Alice" ._:a foaf:mbox ._:a foaf:mbox ._:b rdf:type foaf:Person ._:b foaf:name "Bob" .Truy vn:PREFIX foaf: SELECT ?name ?mboxWHERE { ?x foaf:name ?name . OPTIONAL { ?x foaf:mbox ?mbox } }Vi d liu trn, kt qu truy vn l:namembox

"Alice"

"Alice"

"Bob"

Kt hp cc Pattern vi UNION.SPARQL cung cp mt phng tin ca s kt hp nhng mu th li sao cho mt trong s nhng mu th thay th c th ph hp. nu c nhiu hn mt li gii ph hp, th tt c cc li gii u c tm thy.T kha UNION l c php cho nhng gii php mu. D liu@prefix dc10: .@prefix dc11: .

_:a dc10:title "SPARQL Query Language Tutorial" ._:b dc11:title "SPARQL Protocol Tutorial" ._:c dc10:title "SPARQL" ._:c dc11:title "SPARQL (updated)" . Truy vnPREFIX dc10: PREFIX dc11: SELECT ?titleWHERE { { ?book dc10:title ?title } UNION { ?book dc11:title ?title } } Kt qu truy vntitle

"SPARQL Protocol Tutorial"

"SPARQL"

"SPARQL (updated)"

"SPARQL Query Language Tutorial"

Truy vn ny tm thy ta ca nhng cun sch trong d liu, m ta c ghi li s dng nhng thuc tnh ca Dublin Core t phin bn 1.0 hay 1.1. Nu nhng ng dng mun bit thng tin c ghi li mt cch chnh xc nh th no th truy vn nh sau:PREFIX dc10: PREFIX dc11: SELECT ?x ?yWHERE{ {?book dc10:title?x} UNION {?book dc11:title ?y} }xy

"SPARQL (updated)"

"SPARQL Protocol Tutorial"

"SPARQL"

"SPARQL Query Language Tutorial"

Gii kim traBi 1: Cho d liu RDF v cu lnh SPARQL nh sau:D liu:@prefic pm:.@prefix ex:.ex: a pm: Frame Anh.ex: a pm :Www .ex: b pm: Frame Khanh.ex: b pm : Email Cu lnh truy vn SPARQLPREFIX pm:SELECT ? name ? hpage ?mboxWHERE {?x pm: Frame? name?x pm.Www ? hpageOPTIONAL { ?xpm: Email?mbox }}a. M hnh ha d liu RDF trn theo dng th.b. Cho bit kt qu ca cu lnh SPARQL ni trn vi tp d liu RDF cho v gii thch kt qu.c. Hy vit cu lnh SPARQL hin th tn ca tt c cc ti nguyn c trong d liu trn cng vi trang Web ca h.Gii:a. th

http://example.org/ns#/aAnhhttp://example.org/Anh/Pm:FramePm: Www

http://example.org/ns#/bKhanhmailto:http://example.org/Khanh/Pm:FramePm: Email

b. Kt qu ca cu lnh SPARQL ni trn tp d liu RDF cho v gii thch kt qu.NameHpagembox

Anhhttp://example.org/Anh/

Gii thch: Cu truy vn yu cu xut ra mn hnh Name, hpage v mbox vi iu kin in ra Name v hpage. Nh vy ch hin th trng hp c tn l Anh v trong trng hp pm: a th c tn l Anh v hpage l http://example.org/Anh/ v khng c mbox nn trng. Ngc li, trong b th c name l Khanh nhng khng c hpage m ch c mailto nn trng hp b khng hin th.c. Cu lnh SPARQL hin th tn ca tt c cc ti nguyn c trong d liu trn cng vi trang Web ca h.SELECT ? name ? hpage ?mboxWHERE {?x pm: Frame? nameOPTIONAL { ?x pm.Www ? hpage }}.Bi 2: Cho d liu RDFD liu:# Graph: http://example.org/foaf/aliceFoaf @prefix foaf: .@prefix rdf: . @prefix rdfs: . _:a foaf:name "Alice" . _:a foaf:mbox . _:a foaf:knows _:b . _:b rdfs:seeAlso . rdf:type foaf:PersonalProfileDocument . _:b foaf:name "Bob" . _:b foaf:mbox . _:b foaf:age 32 . # Graph: http://example.org/foaf/bobFoaf @prefix foaf: . @prefix rdf: . @prefix rdfs: ._:1 foaf:mbox ._:1 rdfs:seeAlso . _:1 foaf:age 35 . rdf:type foaf:PersonalProfileDocument .Cu truy vn:PREFIX foaf: SELECT ?src ?bobAgeWHERE { GRAPH ?src{ ?x foaf:mbox . ?x foaf:age ?bobAge }}a. M hnh ha d liu RDF trn theo dng th.b. Cho bit kt qu ca cu lnh SPARQL ni trn vi tp d liu RDF cho v gii thch kt qu.

Giia. M hnh ha d liu RDF trn theo dng th. Trng hp: Alice32

_:b

_:aalice@work.exampleAliceBobbob@work.examplehttp://example.org/foaf/bobFoaffoaf:PersonalProfileDocumentNamemboxknowsageseeAlsomboxnametypeBob

Trng hp: Bob

_:aalice@work.exampleBobhttp://example.org/foaf/bobFoafPersonalProfileDocumentNamemboxageseeAlso35type

b. Cho bit kt qu ca cu lnh SPARQL ni trn vi tp d liu RDF cho v gii thch kt qu.

Bi 3: Cho ti liu RDF c biu din nh sau theo nh dng XML nh sau:

HOANG YENMaster of Education

Leadership4

a) M hnh ho d liu RDF trn theo dng th.b) Lit k cc b ba (Subject-Predicate-Object triple) trong d liu RDF trn.Giic) M hnh ho d liu RDF trn theo dng th.

d) Lit k cc b ba (Subject-Predicate-Object triple) trong d liu RDF trn.SPO

Px:050874Px:nameHoang yen

Px:050874Px: titleMaster of Education

Px:050874Px:teachesPx:EN1101

Px:EN1101Px:courseNameLeadership

Px:EN1101Px:credit4