Mc lc

Mc lc

2I. Gii thiu

2II. Web c ng ngha

3II.1 Siu d liu v vn biu din siu d liu

3II.2 Ontologies

3II.2.1 XML

4II.2.2 XML Namespace

5II.2.3 XML Schema

6II.2.4 RDF

7II.2.5 RDF Schema

8II.2.6 OWL

8III. M hnh S-OGSA

8III.1 Kin trc Grid hung dch v m (OGSA)

9III.3 Nguyn l thit k kin trc tham kho cho h thng Grid Ng Ngha

10III.3 M hnh v kh nng ca Grid Ng Ngha

10III.3.1 M hnh ca Grid Ng Ngha

11III.3.2 Cc kh nng ca Grid ng ngha

13III.4.Cc c ch ca Grid Ng Ngha

14III.5. Kt lun v hung pht trin tung lai

14IV. Mt vi hin thc ca Grid ng ngha

14IV.1. Gii thiu e-Science

15IV.2. Tng quan v myGrid

15IV.2.1. D n myGrid

15IV.2.2. Bi ton v tnh ton li

15IV.2.3. Mc tiu

15IV.2.4. Mt v d

15IV.3. Cc thut ng trong myGrid

15IV.3.1. Workflow

16IV.3.2. Cc thnh phn thit k th nghim

17IV.3.3. Vng i ca mt th nghim

17IV.3.4. Cc thnh phn ng ngha

17IV.4. Kin trc ca myGrid

18IV.5. Cc dch v khi nim

18IV.5.1. Dch v bn th hc

19IV.5.2. Dch v ch gii

19IV.5.3. Kho d liu ca myGrid

19IV.5.4. Dch v ng k

20IV.5.5. Ghi nhn ngun gc v s dng li

20IV.5.6. Dch v khai ph ng ngha

20IV.6. Kt lun

21Ti liu tham kho:

I. Gii thiuGrid ra i nhm h tr vic chia s ti nguyn mt cch an ton, linh hat v c t chc .

Cng ng Grid pht trin mt kin trc chung cho cc h thng Grid, gi l OGSA (Kin trc Grid hung dch v m). Kin trc ny gii quyt nhu cu chun ha Grid bng cch nh ngha mt tp cch chc nng v hnh vi ca mt h thng Grid.Mt h thng Grid mun hat ng phi da trn s am hiu v cc ti nguyn hin c trong h thng, cc kh nng, cch phi hp v khai thc cc ti nguyn . H thng Grid v cc ng dng h tr Grid s s dng cc metadata dng m t thng tin ca ti nguyn Grid mt cch thng minh.Trong cc h thng Grid hin thi, cc metadata ny uc qun l mt cch rt phc tp, khng tung minh, nm n su trong th vin m ca Grid. iu ny dn n vic kh chia s ti nguyn gia cc h thng Grid vi nhau.H thng Grid ng ngha ra i nhm cung cp thng tin giu ng ngha cho cc ti nguyn ca Grid, gip xy dng cc dch v Grid thng minh hn v gip vic chia s ti nguyn gia cc h thng Grid tr nn d dng .

Gird ng ngha l s m rng ca Grid hin ti trong thng tin v dch v c cung cp ngha c nh ngha tt ( well-defined meaning) thng qua cc m t m my tnh c th x l c, cho php chng c s dng bi con ngi v my con ngi v my lm vic cng tc vi nhauGrid ng ngha ch yu da vo cng ngh Web ng ngha trc , ng thi n tun th theo m hnh S-OGSA (m rng t OGSA) thit k cc thnh phn v ng dng ng ngha. Phn II s trnh by cng ngh Web ng ngha ([Nguyn Thanh V]), phn III trnh by m hnh S-OGSA([Hong Song Cm Thch]) v cui cng s l mt vi hin thc ca Grid ng ngha phn IV ([C Nguyn Phng H])II. Web c ng ngha

World Wide Web, gi tt l Web hay WWW, c pht minh v a vo s dng vo khong nm 1990,1991 bi vin s Vin Hn lm Anh Tim Berners-Lee. T n nay n pht trin mt cch rng khp v tr thnh mt dch v khng th thiu trn Internet. Ban u n n thun ch l dch v chia s thng tin nhng ngy nay n dn dn tin ti mt k nguyn mi vi khi nim Web 2.0, cho phep ngi dung co th sa i thng tin trc tip ma khng phai thng qua quyn quan tri, giup cho con ngi trn moi vung lanh th tin lai gn nhau hn.Tuy nhin vn ca Web hin ti l thng tin c biu din di dng vn bn th m ch con ngi mi c th c hiu c. iu ny thc y s ra i ca tng Web c ng ngha (Semantic Web), mt th h mi ca Web, m theo Tim Berners-Lee n 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 cng lm vic vi nhau mt cch hiu qu hn.

Mc tiu ca Web c ng ngha l pht trin cc chun chung v cng ngh cho php my tnh hiu c nhiu hn thng tin trn Web nhm h tr tt hn trong vic khm ph thng tin, tch hp d liu v t ng ha cc cng vic. Phn tip theo s trnh by cc khi nim v cng ngh lin quan n Web c ng ngha.

II.1 Siu d liu v vn biu din siu d liu

Siu d liu trong ng cnh ca Web c ng ngha l cc d liu dng m t ni dung ca trang Web, cho php my tnh c th hiu v x l t ng c.C th ni siu d liu l khi nim u tin v quan trong nht ca Web c ng ngha.

Mt vn c cc nh khoa hc quan tm nht v cng l nn tng nht ca Web c ng ngha l lm th no nhng ng ngha vo cc ti liu web m hin nay c vit bng ngn ng HTML v ch c con ngi mi c hiu c. Hn na vic nhng ng ngha ny phi c thc hin mt cch t ng c th chuyn i hng t cc ti liu web ang c trn World Wide Web thnh cc trang web c ng ngha tng ng. l mt thch thc rt ln m cho n nay vn cha th thc hin c.

Mt thch thc khc lin quan n vn biu din siu d liu l lm sao ngi s dng chp nhn mt chun cng ngh mi (v d nh RDF, RDFS,..) khi vit ti liu web v t lu h quen vi vic s dng HTML v cc cng c lin quan.

II.2 Ontologies

Trong ng cnh ca Web c ng ngha, Ontology c nh ngha nh l mt m hnh d liu biu din mt lnh vc no , cc khi nim trong lnh vc v cc mi quan h gia chng. Hin nay, cc ngn ng ontology quan trng nht bao gm: XML, XML Namespace, XML Schema, RDF, RDF Schema v OWL.

II.2.1 XML

XML (Extensible Markup Language) l ngn ng nh du m rng c pht trin da trn tnh n gin, d s dng ca ngn ng HTML nhng cho php nh ngha cc th (tab) theo nhu cu s dng m t cc ti liu c cu trc m ngn ng HTML khng lm c. XML c thit k cho php my tnh c th trao i ti liu vi nhau thng qua Web m khng lm mt i ngha ca d liu.

Mt ti liu XML bao gm mt tp cc cp th (tab) c lng vo nhau. Mi th c mt cp cc thuc tnh v gi tr. V d:

Nguyn Thanh V 29

Cu trc ca mt ti liu XML: Mt ti liu XML c th c chia thnh hai phn chnh, mi phn c th c cc thnh phn theo quy nh khc nhau: Phn Prolog: cha cc khai bo cho ti liu XML. Phn ny c th cha cc nh ng nh: Cc ch th x l, nh ngha kiu cho ti liu, ch thch, phin bn ang s dng, cch thc m ha d liu, bo co cc ch th x l cho ng dng.V d

Phn thn: cha ni dung d liu, bao gm mt hay nhiu phn t, mi phn t c cha trong mt cp th. Phn t u tin ca ti liu c gi l phn t gc (root element).

Mt ti liu XML c coi l hp khun dng (well-form) nu n tun th cc quy tc sau: Cc khai bo XML cn c t ti dng u tin ca ti liu, chng hn nh khai bo phin bn hay cc ch th x l XML. Mi ti liu XML ch c mt thnh phn gc (root) cha mi thnh phn khc trong ti liu. Cc thnh phn c th ng trc phn t gc l ch thch, ch th x l v nh ngha DTD (nu khai bo phn khi u ca ti liu). Mi phn t ca ti liu phi c nm trong mt cp th. Nu l phn t rng th th phi c kt thc bng "/>". V d: "" Cc thnh phn trong ti liu XML (khc thnh phn gc) u nm gia cp th gc v phi lng nhau mt cch hp l, tc l khng c thnh phn ph, tp hp th ny khng c php chng ln th kia, mi tp trong phi nm trong tp hp ln hn k tip. Cc cp th phi c vit chnh xc nh nhau k c ch hoa hay ch thng. Cc gi tr ca cc thuc tnh u phi nm gia hai ngoc kp. V d: hide=true l khng hp l, m phi l hide="true".II.2.2 XML Namespace

XML Namespace l mt c tnh quan trng ca XML. N cho php gii quyt cc vn lin quan n vic xung t tn cc phn t. Chng ta xem v d di y

2001-01-01

Mr.

V

Nguyn

Grid computing

Foster

Phn t xut hin 2 ln trong ti liu XML v d trn ,ln th nht n m ch danh hiu (Mr, Mss,..) ca mt ngi, ln th hai n m ch ta ca mt quyn sch. l s nhp nhng v tn. W3C gii quyt s nhp nhng y bng cch a ra khi nim XML namespace. Mt XML namespace, thng thng l mt URI, xc nh duy nht mt ti nguyn trn Internet. p dng XML namespace vo v d trn, ta c:

2001-01-01

Mr.

V

Nguyn

Grid Computing

Foster

Ta trnh c s nhp nhng v tn v bn trong Customer th dng namespace http://www.northwindtraders.com/customer v bn trong Book th dng namespace http://www.northwindtraders.com/book.

Mt cch gii quyt khc l khai bo ch vit tt cho cc namespaces ngay u ti liu. Sau bn trong ti liu ta s prefix cc Element cn xc nhn namespace bng ch vit tt ca namespace . V d nh sau:

2001-01-01

Mr.

V

Nguyn

Grid Computing

Foster

Trong ti liu XML trn ta dng 3 namespaces:

http://www.northwindtraders.com/order (namespace mc nh),

http://www.northwindtraders.com/customer (vit tt l cust),

http://www.northwindtraders.com/book (vit tt l book).

Cc phn t khng c prefix (tc l khng c ch tt ng trc) nh BookOrder, OrderNo, v OrderDate, c coi nh thuc v namespace mc nh.

II.2.3 XML Schema

XML Schema l mt ngn ng c dng nh ngha cu trc ca mt ti liu XML nh l phn t no xut hin trong ti liu, quan h cha con gia cc phn t, kiu d liu ca cc phn t,..XML Schema s dng c php ca ngn ng XML v c xem nh mt s thay th cho DTD (Document Type Definition) li thi v kh s dng.

XML Schema m u bng khai bo theo chun XML, tip theo dng tip u ng xsd: khai bo khng gian tn XML Schema, theo c php sau:

.....

II.2.4 RDF

C th ni rng RDF (Resource Description Framework) chnh l nn tng v l linh hn ca Web c ng ngha. RDF l mt ngn ng c dng m t thng tin v nhng ti nguyn trn Web v m t ng ngha ca nhng thng tin y theo cch m my c th hiu c. RDF thch hp trong nhng ng dng m thng tin cn c x l bi my tnh ch khng phi con ngi. RDF cung cp mt framework chung cho vic biu din thng tin ny v th n c th c trao i gia cc ng dng m khng lm mt i ngha ca thng tin. RDF m t ti nguyn trn Web thng qua URI (Uniform Resource Identifier).

Trong RDF, thng tin c th hin bi b ba subject - predicate object hay (Subject,Predicate,Object). V d pht biu Joe Smith has homepage http://www.example.org/~joe s c biu din di dng b ba nh sau (Joe Smith,has homepage,http://www.example.org/~joe). Cc b ba ny c th c biu din di dng th, gi l th RDF (RDF Graph). Tt c cc phn t trong b ba l cc ti nguyn c xc nh duy nht bi cc URI, ring thnh phn object, n c th l URI , l hng chui hoc l mt con s. Ta biu din pht biu Joe Smith has homepage http://www.example.org/~joe bng th RDF nh Hnh 1.

Hnh 1: M t vic biu din thng tin n gin bng b ba Subject- Predicate Object.

Ti nguyn th nht http://www.example.org/~joe/contact.rdf#joesmith m t thng tin cho subject, Joe Smith. Ti nguyn th hai http://xmlns.com/foaf/0.1/homepage m t thng tin cho predicate, has homepage v ti nguyn th ba l http://www.example.org/~joe/ m t thng tin cho object, http://www.example.org/~joe.C php chnh qui cho RDF l RDF/XML. N l s kt hp gia c php ca ngn ng XML v kh nng m t ti nguyn thng qua cc URI ca RDF. Gia RDF/XML v th RDF c s tng ng 1:1. V d, biu din th RDF hnh 2, ta dng c php ca RDF/XML nh sau:

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

xmlns:foaf="http://xmlns.com/foaf/0.1/"

xmlns="http://www.example.org/~joe/contact.rdf#">

Smith

Joe

Hnh 2: th RDF m t Joe SmithII.2.5 RDF Schema

RDF Schema (RDFS) l s m rng ca RDF cho php m t s phn loi ca cc lp (classes) v cc thuc tnh (properties). RDF Schema nh ngha cc classes v properties m t cc classes, properties v cc ti nguyn khc.N cng c th xem nh l mt s m rng ng ngha ca RDF cung cp nhng c ch cho php m t cc nhm ca cc ti nguyn lin quan v mi quan h gia cc ti nguyn ny.

Trong RDFS, classes l mt nhm cc ti nguyn c lin quan vi nhau. Bng Hnh 3 lit k danh sch cc classes trong RDFS

Element Class of rdfs:subClassOf rdf:type

rdfs:Resource all resources rdfs:Resource rdfs:Class

rdfs:Class all classes rdfs:Resource rdfs:Class

rdfs:Literal literal values rdfs:Resource rdfs:Class

rdfs:Datatype datatypes rdfs:Class rdfs:Class

rdf:XMLLiteral XML literal values rdfs:Literal rdfs:Datatype

rdf:Property properties rdfs:Resource rdfs:Class

rdf:Statement statements rdfs:Resource rdfs:Class

rdf:List lists rdfs:Resource rdfs:Class

rdfs:Container containers rdfs:Resource rdfs:Class

rdf:Bag unordered containers rdfs:Container rdfs:Class

rdf:Seq ordered containers rdfs:Container rdfs:Class

rdf:Alt containers of alternatives rdfs:Container rdfs:Class

rdfs:ContainerMembershipProperty rdf:_1... Properties expressing membership rdf:Property rdfs:Class

Hnh 3: RDFS classes

Properties trong RDFS chnh l quan h gia cc Subjects v Objects trong RDF. Danh sch cc properties c lit trong trong bng Hnh 4.

Element Relates rdfs:domain rdfs:range

rdfs:range restricts subjects rdf:Property rdfs:Class

rdfs:domain restricts objects rdf:Property rdfs:Class

rdf:type instance of rdfs:Resource rdfs:Class

rdfs:subClassOf subclass of rdfs:Class rdfs:Class

rdfs:subPropertyOf subproperty of rdf:Property rdf:Property

rdfs:label human readable label rdfs:Resource rdfs:Literal

rdfs:comment human readable comment rdfs:Resource rdfs:Literal

rdfs:member container membership rdfs:Resource rdfs:Resource

rdf:first First element rdf:List rdfs:Resource

rdf:rest rest of list rdf:List rdf:List

rdf:_1, rdf:_2, ... container membership rdfs:Container rdfs:Resource

rdfs:seeAlso further information rdfs:Resource rdfs:Resource

rdfs:isDefinedBy definition rdfs:Resource rdfs:Resource

rdf:value For structured values rdfs:Resource rdfs:Resource

rdf:object object of statement rdf:Statement rdfs:Resource

rdf:predicate predicate of statement rdf:Statement rdfs:Resource

rdf:subject subject of of statement rdf:Statement rdfs:Resource

Hnh 4: RDFS Properties

II.2.6 OWL

OWL ( Web Ontology Language) l mt s m rng t RDF v RDFS. Mc ch chnh ca OWL l a kh nng suy lun vo Web c ng ngha. OLW c ba loi: OWL Lite, OWL DL v OWL Full. Mi loi OWL s c nhng c tnh ring v do s ph hp trong ng cnh ca mt ng dng no .

III. M hnh S-OGSAIII.1 Kin trc Grid hung dch v m (OGSA)

OGSA nh ngha mt tp nhng chc nng, dch v v hnh vi c bn ca mt h thng Grid .Cc chc nng ny bao gm : Cc dch v c s h tng , dch v v d liu , dch v qun l ti nguyn , dch v qun l vic thc thi , dch v bo mt , dch v t qun l , dch v thng tin .

Hnh 5.Kin trc ca Grid Ng Ngha

Kin trc OGSA l mt m hnh kin trc 3 lp (3-tiers) .Lp c s gm cc dch v c s h tng uc o ha thng qua cc webservice .Lp gia bao gm cc dch v li uc gi l Grid Middleware . Lp trn cng l lp cc ng dng Grid . Lp ng dng s s dng cc dch v ca lp Middleware xy dng cc chc nng cho ngui s dng .

III.3 Nguyn l thit k kin trc tham kho cho h thng Grid Ng Ngha

Kin trc ca Grid Ng Ngha uc thit k da trn 6 nguyn l sau :

Tnh tinh gin ca cc thnh phn kin trc: kin trc Grid mi cn phi tinh gin cn thit gim thiu nhng nh hung ln kin trc Grid v cc cng c truyn thng

Tnh c th m rng ca framework: nh ngha mt kin trc c th m rng v ty bin thay v nh ngha mt kin trc y v tng qut .

Tnh thng nht ca c ch: Grid Ng ngha cng l Grid , v th tt c cc thc th ca Grid Ng Ngha cng u c tnh cht ging nh cc thc th ca Grid thng thung, cc tnh cht l :

-Cc ti nguyn ca Grid Ng ngha c th qun l uc .Cc m t ng ngha c trng thi v thi gian sng .- Grid Ng Ngha phi h tr cc dch v c trng thi (stateful) v khng trng thi (stateless) ging Grid thng thung

- Cc dch v tri thc (Knowledge services) trong Grid Ng Ngha cng tun th cc c t ca cc dch v Grid thung .

Tnh a dng ca cc kh nng ng ngha:trong h thng Grid Ng Ngha cc thc th c th c nhiu mc kh nng h tr ng ngha khc nhau :

-Cc thc th khng h tr ng ngha

-Cc thc th hiu ng ngha nhng khng th x l ng ngha

-Cc thc th hiu ng ngha v c kh nng x l ng ngha y hoc bn y .

Tnh a dng ca vic biu din ng ngha :

- Ng ngha ca cc thc th c th uc m t , biu din nhiu dng khc nhau nh : text , logic, ontology ,rule.

Tnh d chuyn i ca cc dch v sang ng ngha(Enlightenment of services):

- Kin trc Grid Ng Ngha nn gim thiu nhng nh hung khi thm tnh ng ngha vo trong cc thc th , dch v ca Grid thng thung .Nhm gip vic chuyn t grid thung sang grid ng ngha uc d dng v nhanh chng .

- Cc thc th Grid khng b ph v nu n s dng v x l cc ti nguyn Grid nhng x l cc ng ngha kt hp vi cc ti nguyn .

- Trong sut thi gian sng (lifetime) ca chng ,cc th th Grid c th c hoc mt tnh ng ngha .

Kin trc Grid Ng Ngha c b kh nng chnh : m hnh (model, cc thc th Grid ng ngha ), kh nng (capabilities , chc nng ca cc th th ng ngha), c ch (mechanism) .

III.3 M hnh v kh nng ca Grid Ng Ngha

III.3.1 M hnh ca Grid Ng Ngha

M hnh ca Grid Ng Ngha uc bao gm cc thnh phn sau :

- Cc thc th Grid (G-Entities):l bt k i tng no c s nhn dng (identity ) trong Grid, bao gm cc ti nguyn v cc dch v .

- Cc thc th tri thc (K-Entities):y l lai thc th c bit c th hat ng vi cc dng tri thc .Cc thc th tri thc gm : Ontologies, Rules, C s tri thc ,hay cc m t dng text ca tri thc m c th chia s uc .Cc dch v tri thc l nhng dch v c th hat ng v truy cp ti cc ti nguyn tri thc nh cc ng c lut, b suy din t ng

-Cc rng buc ng ngha (S-Bindings):l cc thc th dng biu din s kt hp gia mt thc th Grid thng thung (khng c tnh ng ngha ) vi mt hoc nhiu thc th Grid ng ngha .

-Cc thc th Grid Ng Ngha (SG-Entities):l cc cc rng buc ng ngha hay cc thc th tri thc

Hnh 6.Mi quan h gia cc thc th grid thung v ng ngha

III.3.2 Cc kh nng ca Grid ng ngha

Theo nguyn l thit k v tnh a dng (diversity) , Grid Ng Ngha bao gm mt tp cc dch v cc cc cp khc nhau v kh nng x l ng ngha .Cc dch v ng ngha uc chia thnh hai nhm :nhm dch v cung cp ng ngha (Semantic Provisioning Services -SPS ) v nhm dch v hiu ng ngha (Semantically Aware Grid Services -SAGS).Nhm dch v SPS chu trch nhim cung cp v qun l s kt hp ng ngha cho cc thc th Grid thung .Nhm dch v SAGS l nhng dch v Grid m rng c th x l ng ngha . Cc dch v cung cp ng ngha (SPS)

Cc dch v cung cp ng ngha l cc dch v cho php to, lu tr , cp nht, lai b v truy cp cc dng siu d liu v tri thc khc nhau .

Cc dch v cung cp ng ngha uc phn thnh hai lai chnh : nhm dch v cung cp tri thc v nhm dch v cung cp rng buc ng ngha .

Nhm dch v cung cp tri thc (Knowledge provisioning services) gm: cc dch v ontology chu trch nhim lu tr ,truy xut cc m hnh tri thc nim v cc dch v suy din chu trch nhim tnh suy din trn cc m hnh tri thc ny .

Hnh 7.M hnh thng tin ca Grid Ng Ngha

Cc dch v ontology cung cp truy cp n cc tri thc lu tr trong cc ontology , dng cc khi nim v mi quan h gia cc khi nim v rng buc ca cc mi quan h .Cc ontologies c th uc truy cp thng qua cc ngn ng truy vn hoc cc API .

Cc dch v suy din cho php suy din cc thng tin mi v kim tra cc rng buc trn cc tri thc c trong ontologies .

Nhm Cc dch v cung cp rng buc ng ngha gm:cc dch v v siu d liu (metadata services) chu trch nhim lu tr truy cp n cc rng buc ng ngha , sinh ra cc siu d liu cho cc ti nguyn Grid t nhiu ngun thng tin khc nhau .

Dch v siu d liu chu trch nhim lu tr v cung cp truy cp n cc rng buc ng ngha .Cng ging nh cc dch v Ontology , cc siu d liu c th uc truy cp thng qua ngn ng truy vn hoc cc API .C mi quan h cht ch gia cc dch v siu d liu v ontology , bi v d liu uc lu tr b dch v siu d liu thng thung uc da trn cc m hnh nim uc lu tr trong cc ontology .Cc dch v siu d liu c th s dng cc dch v ontology v suy din suy din cc d liu m chng lu tr .

Cc dch v hiu ng ngha

L nhm cc dch v c th khai thc cc k thut x l tri thc to cung cp cc chc nng .Hiu ng ngha tc l c kh nng s dng cc rng buc ng ngha v hnh ng da trn cc siu d liu v tri thc . Mt s v d v cc hnh ng theo ng ngha nh :

- Vic xc thc cho mt i tung Grid da vo thng tin siu d liu uc thc hin bi dch v qun l t chc o (VO Manager service) .

-Vic thc thi mt yu cu tm kim trn cc entries trong danh mc ti nguyn ng ngha .

-Vic tch hp mt khi nim mi vo ontology uc qun l bi dch v ontology .

Kin trc Grid ng ngha cho php vic chia s tri thc gia cc cng ng Grid mt cch d dng v thun tin .III.4.Cc c ch ca Grid Ng Ngha

Xem cc thc th tri thc v cc rng buc ng ngha nh ti nguyn Grid

S dng cc dch v c trng thi ng ngha cung cp cc rng buc c ng ngha cho cc ti nguyn .

Cc dch v Grid Ng Ngha c xy dng da trn Framework ca web service (WSRF)Kin trc Grid Ng ngha l mt s m rng ca kin trc Grid thng thung gip cho vic x l cc dng siu d liu (ng ngha ) uc linh hat v d dng .

nh ngha uc mt tp cc dch v x l ng ngha quan trng .

a ra uc cc nguyn l thit k nhm k tha nhng c tnh ca n tng Grid hin ti.

Tuy nhin vn cn nhiu thch thc v hn ch cn phi khc phc pht trin h thng Grid Ng Ngha Hnh 8.m hnh truy xut cc rng buc ng ngha ca cc ti nguyn

III.5. Kt lun v hung pht trin tung lai

:

-Nhng thch thc v mt k thut :v mt hin thc ln l thuyt

-Hiu sut x l ng ngha

-Tp hp v qun l ni dung ng ngha

-Nhng thch thc lin quan n cc vn php l ,bo mt ,tnh ring t khi chia x ti nguyn gia cc h thng Grid

IV. Mt vi hin thc ca Grid ng ngha

IV.1. Gii thiu e-Science

Cm t e-Science c s dng m t khoa hc tnh ton tp trung cao (computationally intensive science) c tin hnh trn mi trng mng phn b cao, hay khoa hc s dng tp d liu khng l cn n mi trng tnh ton li. Cm t c to ra bi John Taylor, Tng gim c ca Phng Khoa hc v Cng ngh ca Vng quc Anh vo nm 1999.

Mc tiu ca sng kin e-Science l xy dng mt h tng c s cho php cc nh khoa hc tin hnh nhng nghin cu khc nhanh hn, v tt hn. e-Science bao gm vic xy dng phn mm li v cc ng dng v khoa hc k thut trin khai trn phn li ny. Mt s ng dng c cc trng i hc trong nc ngh c th k ra nh: vt l phn t v thin vn, k thut v khoa hc vt cht, khoa hc v sinh hc, y t v mi trng, phn tch mu protein, sinh hc cu trc, sinh hc ton cu, s lo ho sinh hc. Ngoi ra, mt s ng dng mang tm thch thc ln lao i hi s hp tc mang tnh hc thut nh: Advanced Knowledge Technologies, Medical Images and Signals, Equator, DIRC (Dependability).

Phn tip theo xin c gii thiu v d n myGrid c ngh bi trng i hc Southampton v Manchester, Vng quc Anh.

IV.2. Tng quan v myGrid

IV.2.1. D n myGrid

D n myGrid l mt trong nhng d n v e-Science ca United Kingdom vi mc ch xy dng middleware cho cc th nghim in silico thc hin bi nhng nh khoa hc trong phng th nghim t ti nguyn (under-resourced labs), ngi m s dng nhng ng dng ca ngi khc. Phn tch chui (sequence), phn tch siu ma trn (microarray), protein, ho tin hc (chemoinformatics), x l hnh nh, biu din cc bn mu Dilbert.

IV.2.2. Bi ton v tnh ton li

l bi ton v s chia s ti nguyn gia cc tp hp khng c nh cc c nhn, cc c quan, v cc ngun ti nguyn mt cch hp tc, linh ng, v bo mt. Ti nguyn y bao gm: my tnh, c s d liu, ti liu lu tr, con ngi, thit b, kho workflow, cc lu c nhn, cc trang web, cc c quan

IV.2.3. Mc tiu

Mc tiu l xy dng cc cng c cho ngi lp trnh pht trin, cho cc nh khoa hc s dng ng dng, v cho cc nh cung cp tch hp cc ng dng mi.

IV.2.4. Mt v d

V d bnh Graves Disease, gy ra do s t min dch ca tuyn gip, khi h min dch tn cng tuyn gip v gy ra s hot ng qu mc, dn ti bu c, tng mch p, st cn, yu cBnh gy ra do s kch thch ca khng th ln c quan cm th tuyn gip, iu ny c qui nh b mt bi t bo lympho trong h min dch. Nh vy, c s khoa hc phn t no chu trch nhim cho phn ng t ng min dch ny. y l mt vn sinh hc m myGrid hng ti gip gii quyt.

IV.3. Cc thut ng trong myGrid

IV.3.1. Workflow qun l cc th nghim, ngi ta dng thut ng workflow m t v lu tr tng giai on ca th nghim, m mi giai on ny c th ging nhau nhng th nghim khc nhau, iu ny cho php ngi dng c th trao i mt cch linh hot cc tin trnh v kt qu th nghim.

- Ngn ng nh ngha workflow l WSFL subset , XScufl.

- Khai ph workflow: l qu trnh tm kim nhng workflow c thc hin.

- To workflow: l qu trnh tm kim cc lp dch v c lin quan, hoc to ra chng nu khng tm thy.

Hnh sau l mt v d v workflow.

IV.3.2. Cc thnh phn thit k th nghimBao gm c t workflow, c t cu query, mc tiu m t ghi ch, ng dng, c s d liu, bi bo lin quan, cc trang web quan trng. Cc thnh phn thit k ny c th phn thnh 2 loi: thc th th nghim v thnh phn lin kt.

-Cc thc th th nghim: h s ghi chp ca cc th nghim, kt qu d liu, lch s s dng dch v bi b my workflow, thc th dch v, tp thong s cho cc ng dng, li ch gii v kt qu.

-Cc thnh phn lin kt: ng vai tr gom nhm v lin kt cc thnh phn thit k v thc th, nh mt cu query v kt qu, mt workflow v kt lun, mt workflow v cc phin bn trc v sau n, mt nhm nhng thng tin ny c lin kt n ti liu ca cc nh sinh tin hc.

IV.3.3. Vng i ca mt th nghim-Hnh thnh th nghim

-C nhn ho

-Thc thi th nghim

-Qun l th nghim

-Cung cp th nghim

-Khm ph v s dng li

Hnh sau m t vng i ca mt th nghim.

IV.3.4. Cc thnh phn ng ngha-C s d liu: d liu m t ni dung v ngha ca dch v v ti nguyn.

-Thut ng: chia s vn t vng thng dng, h tr cc b my tm kim, i l, tc gi, ngi dng.

-Bn th hc: l cc hiu bit chung v c th chia s trong mt phm vi, cn thit trong vic trao i, tm kim v khm ph.

IV.4. Kin trc ca myGrid

Kin trc ca myGrid gm c 3 tng. Tng cao nht l ng dng, dnh cho cc nh sinh tin hc. Tng quan trng nht l dch v li, do cc nh pht trin phn mm, gm c 3 phn chnh l c s d liu ng ngha, qun l th nghim, v qun l d liu. Tng thp nht l dch v bn ngoi, gm nhng dch v grid ni chung, dnh cho cc nh cung cp dch v.

1. Cc thnh phn thuc core services

-C s d liu ng ngha: bao gm ng k bn th hc, khai ph workflow v dch v.

-Qun l th nghim: gm vic c nhn ho, qun l ngun gc, cnh bo.

-Qun l d liu: qun l d liu v truy xut cu truy vn.

2. Ngn ng m t d liu v bn th hc-OWL

OWL l ngn ng din cm m t cc khi nim, cc mi quan h, cc rng buc, v cc tin . Chnh xc v hon chnh, hiu qu, hp l suy lun cc mi quan h gia cc khi nim hn l khng nh chng, bao gm c vic phn cp. RDF, Resource Description Framework, l ngn ng m t c s d liu trn web, hnh thnh th b ba (ch ng, i tng, tn ng), kt hp cc a ch URIs vi nhau v vi cc khi nim trong OWL.IV.5. Cc dch v khi nim

IV.5.1. Dch v bn th hc Qun l cc biu thc khi nim. Dch v ny c mi trng pht trin l OilEd, c b suy lun FaCT dung suy ra cc biu thc khi nim. C c ch so trng khng chnh xc v c ch xp hng tm ra kt qu hu hiu nht bng cch suy lun thng qua cc m t v sinh ra cc cu trc phn loi. Cc thc th lu tr cho thc th ch s ca cc biu thc khi nim trong thanh ghi v c s d liu.

IV.5.2. Dch v ch giiR sot cc i tng ch gii v xem cc ch gii ny.

IV.5.3. Kho d liu ca myGridLu tr cc thnh phn th nghim (gm c t ca cc workflow bng cc ti liu XML, d liu, cc ghi ch XML). Cc hnh thc lu tr: ti liu XML, c s d liu quan h, RDF.

IV.5.4. Dch v ng kCng b cc thnh phn th nghim: dch v, workflow

IV.5.5. Ghi nhn ngun gc v s dng liFreeFluo cung cp h s ngun gc chi tit lu tr trong c s d liu m t vic g c thc thi, vi dch v g v khi no, lu tr di dng ti liu XML.

IV.5.6. Dch v khai ph ng ngha-Cc dch v v workflow c lu tr trong thanh ghi c cc m t bng RDF v OWL.

-S la chn mt dch v hay mt workflow l ty thuc vo tham s c s dng, kt qu c sinh ra, nhim v c tin hnh...

-Truy xut d liu trong c s d liu dng thanh ghi RDF UDDI.

-C ch so trng da vo c ch phn loi FaCT OWL cho c s d liu hng khi nim.

IV.6. Kt lun

Tm li, vic s dng khi nim c th:

-Cc t vng iu khin cng b cc dch v v cc workflow.

-nh ch s index trn thanh ghi gip khai ph ng ngha cc dch v v workflow cng nh lu tr d liu trong kho.

-Gip xy dng cc workflow c ng ngha.

-nh hng gia d liu v tri thc: lin kt cc mc trong kho d liu v ghi nhn ngun gc ca cc workflow.

Ti liu tham kho:

1. A Semantic Web Primer Grigoris Autoniou and Frank van Harmelan

2. An overview of S-OGSA: a Reference Semantic Grid Architecture - Oscar Corcho, Pinar Alper, Ioannis Kotsiopoulos, Paolo Missier, Sean Bechhofer and Carole Goble School of Computer Science The University of Manchester, Manchester, UK 3. The Semantic grid A Future e-Science Infrastructure, David De Roure, University of Southampton, UK

4. Provenance challenge --- myGrid, David De Roure, University of Southampton, Jun Zhao, Carole Goble and Daniele Turi, University of ManchesterPAGE 6