web grid services

8/2/2019 Web Grid Services

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Web and Grid ServicesArchitectures and Technologies

Savas Parasta tid is

http://savas.parastatidis.name


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Overview

Servic e Orientation vsOb jec t Orientation

Web Servic es Arc hitec ture a nd Tec hnolog ies

Grid Servic es Arc hitec ture and Tec hnolog ies Comparison

Briefly what we a re up to here

References/ Links


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Service Orientation

Servic es Oriented Arc hitec ture (SOA) Agents (software or human)

Emphasis on act ions

Agent-to-ag ent interac tion through messag e exc hange

A servic e is a set o f ac tions tha t form a c oherent wholefrom the point o f view of servic e p roviders and servic e

requestersSource : W3C Web Servic es Arc hitec ture Doc ume nt (Draft 21/ 7/2003)


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Object Orientation

Objec t-Orientat ion Modelling of entities

Emp hasis on sta te encapsula tion, inheritanc e, interfac es

Ob jec t id importa nt

An ob jec t has sta te, behaviour, and identity; thestruc ture and behaviour of simila r ob jec ts a re defined in

their c ommon c lass; the terms instanc e and ob jec t a reinterchangeableSource : Booc h, Grad y. Ob ject -Oriented Design With Ap p lica tions. Benjam in Cummings

An ob jec t-c entric (ra ther than c lass-c entric ) definition


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Objects

Method c allsand results

Methods Instance

Interface


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Objects

Method c allsand results


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Service Orientation vs Object Orientation

Two d ifferent pa rad igms (?)

Perhap s not widely-ac c ep ted statements Servic e-Oriented Arc hitec tures a re more suitab le for loosely coup led d istributed

app lic a tions (Web Servic es Architec ture) Ob jec t-Orienta tion encourages c losely coup led d istributed app lic a tions (i.e.,

CORBA, DCOM, etc .)

Distinc tion not c lea r to some (espec ia lly to the CORBA

and J2EE c ommunity)


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Web Services Architecture

Follows the SOA conc epts

Emp hasis on interop erab ility XML, XML, XML

Prog ramming mod el, imp lementation tec hnology, opera ting systemunaware

Orig inally three spec ific a tions were seen as the foundation o f thearchitecture

SOAP (Simp le Ob jec t Acc ess Protoc ol well, not anymore!)

WSDL (Web Services Desc rip tion Language)

UDDI (Universa l Desc rip tion, Discove ry and Integ ra tion)

SOAP and WSDL

are the most importanttec hnolog ies but

publish bind

find


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Web Services Architecture

Messages

CommunicationsHTTP, SMTP, FTP, JMS, IIOP, ...

SOAP

SOAP Extensions

Reliab ility, Correla tion, Transac tions, ...

DescriptionsWeb Servic es Desc rip tion (WSDL)

Processes

Disc ove ry, Agg reg a tion, Choreo graphy, ...

Messages

CommunicationsHTTP, SMTP, FTP, JMS, IIOP, ...

SOAP

SOAP Extensions

Reliab ility, Correla tion, Transac tions, ...

DescriptionsWeb Servic es Desc ription (WSDL)

Proc essesDisc overy, Agg reg ation, Choreography, ...

Source : W3C Web Servic es Arc hitec ture Doc ume nt (Draft 21/ 7/2003)


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A Web Service

It is an agent, a softwa re system, a c omponent

A possible d efinit ion A Web servic e is a software system identified by a URI, whose p ub lic inte rfac es are d efined

and desc ribed using XML. Other systems ma y interac t with the Web servic e in a manner

p resc ribed by its definition, using XML based messages c onveyed by inte rnet p rotocols.Sourc e: W3C Web Service s Architec ture Doc ume nt (Dra ft 21/ 7/2003)

It isNOT A web page

A web server

A Java Server Page Related to Web b rowsers or po rtals

Some more a c ronyms, protocols W3C :-)

OASIS (Organisa tion for the Ad vancement of Struc tured Informa tion Standards)

WS-I (Web Servic es Interop erab ility)

WS-Routing, WS-Referra l, WS-Sec urity, WS-Federa tion, WS-Co ord ina tion, WS-Transac tions, WS-Cho reography, WS-Policy, WS-Reliab leMessaging, WS-Ad dressing, WS-Atta c hments, DIME,WS-Inspec tion, BPEL4WS


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The idea

Source: Dr Jim Web be r s NOOPS p resenta tion on Ad vanc ed Web Services Deve lopme nt


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The basics - SOAP

An XML-based messagingformat and framework

The c urrent choic e of wire

format Version 1.2

Roles

Envelope

Header

Body

Envelope

Header

Body


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The basics - WSDL

An XML-ba sed interfac edesc rip tion language for WebServic es

Protoc ol desc ript ion messag eexchanges

Very important forinteroperability

Current version 1.1 (work on 1.2or 2.0)

servic e

port

binding

portType

operation

1...N

1

1

0...N

messages

0...N

0...N

messageParts

servic e

port

binding

portType

operation

1...N

1

1

0...N

messages

0...N

0...N

messageParts


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Caution

...you are about to enter the Grid


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The Grid Architecture

In the beg inning there was Glob us for the Grid

Then Web Servic es c ame a long and everyone ta lkedabout them

So the Globus team decided to c reate Grid Services

The Globa l Grid Forum (GGF) wa s formed to standard isea services-based infrastruc ture for the Grid

But first


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What is the Grid?

Neo, the Grid is everything you would like it to be

Just few Virtual orga nisat ions

Integration o f distributed resourc es

Universal computer

Interc onnection tec hnologies for superco mputers

Or if you are a technologist An applica tion dom ain for the Web Services idea s and tec hnologies

Or if you are a researc her/ ac ad emic A new set of interesting p rob lems (a t a g lob al sc ale)

A (new?) pa rad igm for distributed c omputing

Or if you are a cynic Another way for com panies like IBM to sell you infrastruc ture solutions

A way for the globusteam to get more public ity

A way for the main Grid people to get awa rds

A way for resea rc hers to re-re-re-re-investiga te the same idea s on d istributed c omputing

A fantastic wa y to see the world (a lot of travelling for GGF meetings)


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A stack-based view

Web Servic es Technolog ies

OGSI

OGSA

Grid Applications

Web Services Technolog ies

OGSI

OGSA

Grid Applic ations


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A stack-based view


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OGSA

Open Grid Servic es Arc hitec ture The v ision

The collect ion of services

Does not c rea te spec ific a tions, just talks about them

How does one build a ll those servic es? Use Web Services

or

Identify Grid -spec ific p rob lems that need to be addressed and then dec ide whether WebServices standards c an p rovide the solution

The Grid Arc hitec ts dec ided that there were enough req uirementsin the ir servic es-oriented a rc hitec ture tha t were not met by the WebServices sta ndards

They c ame up with OGSI

A servic e is a Grid Servic e only if it adheres to the OGSIspecification

And the a nswer to the million dolla r questionGrid Services AREWeb Servic es (well it depends:-)


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OGSI

Open Grid Servic es Infrastruc ture GWSDL (Grid WSDL)

Introd uc es Service Da ta Elements (SDEs) (a ttributes in next version of WSDL)

portType inheritanc e (next version o f WSDL)

Grid Servic e Hand le (GSH)

Grid Servic e Referenc e (GSR)

Fac tory

Handle reso lver

No tifica tion Servic e group s (light-we ight reg istries)

GRID SERVICE INSTANCESGRID SERVICE INSTANCES


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OGSI

Introduces semantic s and c apab ilities to Web Servic es Sta tefulness (SDEs)

Stateful interac tions

Transient instanc es (Fac tories!!!)

Life time management

Introspec tion!!!

Notifica tion on state c hanges


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How to Grid

You can use the GlobusToolkit 3 A reference imp lementation of OGSI (Glob usToolkit 3 Core)

OGSA servic es

GT2 servic es expo ses as OG SI Services

WS-Security Or, you can use the GlobusToolkit 3

Or even the Globus Toolkit 3

Some other imp lementat ions Fujitsu/Unic orn core imp lementation

OGSI.NET (University of Virg inia )

MS.NETGrid (NeSC + EPCC)

Perl (University of Manchester)

Python coming? (Globusteam)

Interoperab ility c onc erns Everyone is interoperab le with GT3

(they a re using the b ind ings tha t c om e w ith GT3)


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Web services interaction

Sta teless interac tion

Hey, I am savas


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Welc ome savas


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I would like 100 please


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No c ant do dont know you


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Stateful interac tion

Hey, I am savas

context


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Welc ome savas

c tx


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I would like 100 please

c tx


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Your 100

c tx


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c tx

c tx

c tx


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Grid services interaction



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GSI


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I would like 100 p lea se


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Your 100


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The OGSI view

SOAP and WSDL

Web servic es

D W G i S i


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Data and Web/ Grid Services

Web Servic es Messages exchange

Doc uments

No notion o f po inter

Servic e orientat ion?

Grid Servic es The a rc hitec ture encourages everything to be exposed through a n interfac e

ra ther than b eing sent as a doc ument

GSH is the pointer Objec t orientation? (CORBA?)

N tl d th f t f OGSI


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Newcastle and the future of OGSI

Proposa ls for d isc ussion

Make OGSI an app lic a tion framework that uses Webservic es c oncep ts and tec hnolog ies

No c hanges/ add itions/ extensions to spec ifica tions

Utilise existing/ upc oming Web servic es tools

One should be a b le to build a servic es-based

infrastruc ture for the Grid by pic king and mixing tools

Wh t t t


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Where to start

XML

XML

XML

XML Sc hema

WSDL

SOAP

OGSI spec ific a tion and p rimer

Links


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Links

W3C http :/ / www.w3c.org

OASIS http :/ / www.oasis-op en.org

Mic rosoft http:/ / msdn.mic rosoft.c om/ webservic es

IBM - http :/ / ww w-106.ibm.c om/ develop erworks/ webservic es/ GGF http:/ / www.gridforum.org

OGSI WG https:/ / forge.grid forum.org/ projec ts/ ogsi-wg

OGSA WG https:/ / forge.grid forum.org/ projec ts/ ogsa-wg

NEReSC http:/ / www.neresc .ac .uk (to b e upd ated soon)

Plea se do c onta c t me: Savas.Parasta tid is@newc astle.ac .uk

web grid services

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