steffen staab isweb – information systems & semantic web semantic management of web services...

Steffen Staab

ISWeb – Information Systems & Semantic Web

Semantic Management of Web Services

Steffen Staab

Prague

May 19, 2005

Steffen Staab


Hopes

• Describe a goal – let the work be done by Semantic Web Services (previously „agents“, „PSMs“,…)

• Projects like – EU: DIP, ASG, Ibrow, …– IBM India: see WWW2005– US: OWL-S

Steffen Staab


Costs

Granularity of Modelling

Management Costs

coarse fine

low

high

Hopes

SWS

RPC

WS*

Steffen Staab


Costs


Management Costs

ModellingCosts

coarse fine

low

high TotalCosts

Humbleness in Front of Total Costs

RPC

SWS

WS*

Steffen Staab


Humbleness

• What are the most urgent problems?

• Where are the largest benefits

• Analogy/Pseudoquote from Mohan (Sigmod Record, 2004):

„Relational Databases were so successful, because people would have to write 20 times more code if they would not use them.

Therefore, people could do things that they were not able to do otherwise, because they would not have been able to write 20 times more code.

Therefore, people put up with early relational database mgmt systems, which were unstable, had many problems, etc.“

Where is this huge need for Semantic Web Services?

Better be incremental!

Steffen Staab


Hope, Humbleness and Hope again…

• Web Services

• Middleware» They are a huge mess!» Though they have clear conceptual underpinnings,

they are complex beasts!» Semantic Technologies can do something for them!

» Let‘s backtrack how!

Steffen Staab


Situation AIFB 1999 – not about Web Services

Portal1 Portal2

Portal3

Portal4

KnowledgeManagementApp

...

External

Internal

SemanticWeb Service x

Semantic Web

Steffen Staab


Contribution of this talk

ASSW facilitates application development in the Semantic Web

Semantic Web technology is used within the ASSW

Semantic Web ASSW

helps

helps

Semantic Web Web Services

helps

helps

Web Services facilitate application development (in the Semantic Web)

Semantic Web technology is useful for Web Services

Application Server for the Semantic

Web

Steffen Staab


Agenda

• Application Server– Semantic Web for Application Server

• Problem• Ontology• Use Cases

– Development Time– Run Time

• Ontology Design• Architecture• Implementation• Relationship to MDA • Conclusion

– App Server for Semantic Web

• Semantic Management of Web Services

Steffen Staab


Complexity in Application ServersMultitude of XML-DTDs

Problem

web.xml

ejb-jar.xml

application.xml

.htaccessMLETs

login-config.xml

...

OntologyResourcesUsers

Dependencies Access Rights...<web-app><servlet> <servlet-name>JMXInvokerServlet... <servlet-class>org.jboss....</servlet-class> <init-param> ... </init-param> <load-on-startup>1</load-on-startup>... <security-constraint> ... </security-constraint>

<login-config> <auth-method>BASIC</auth-method> <realm-name>HTTP Invoker</realm-name> </login-config>

<security-role> <role-name>HttpInvoker</role-name></security-role>...

Steffen Staab


• Ontology is explicit conceptual model

• Formalizes properties, relationships and behaviors of components

• Aims at conceptualizing „shared“ understanding

• Logics-based formal semantics

• Axioms

• Allows reasoning

• Allows conceptual querying

Ontology

Ontology

Semantic Metadata

Schema level

Instance level

CustomerEJB

instOf

Component

EnterpriseBean MBean

Steffen Staab


Use Cases Development Time

• Component dependencies and versioning

• Licensing– model development constraints

• Capability descriptions– make component capabilities explicit

• Semantics of parameters– associate names with ontology

• Automatic generation of component and service metadata– beyond java2wsdl

WebShop-Servlet

WebShop-Servlet

Customer Entity Bean

Recommender-Servlet

Recommender-Servlet

News-Servlet

News-Servlet

...

...Lib

Lib

LibLib

Lib

Steffen Staab


Use Cases Run Time• Access Rights

– E.g. indirect permissions

• Error handling– Avoid exceptions thrown to the user

• Transactional settings– Discover components that do not support transactions

• Secure communication– Discover non-encrypting components

Customer

Anonymous

WebShop-Servlet

WebShop-Servlet

Customer Entity Bean

Admin

ContextSwitch

...

Steffen Staab


Ontology Design Ontology Design

– Syntactic vs. Semantic Metadata– Generic vs. Domain Knowledge– Modular

C om p on e n t

G ro u n d in gP r o f i le

ID L

A P I D esc r ip t io n

Im p lem e n ta tio n

D o m a inA P I D esc r ip t io n

D o m a in P r o f i le s

G e ne ra lity

Dom

ain

G

ener

ic

Semantic Syntactic

Metadata M

etadata

ontology moduleuses module

app lica tion.xm lw eb .xm lejb -ja r.xm l...

D o m a in O n to log y M o du le s

CapabilityDescriptions

Container

Semantics of parametersAutomatic generation

Domain Knowledge

Implementation detailsMapping to source code

Syntactic vs.Semantics

Steffen Staab


InferenceEngine

Architecture

web.xml

ejb-jar.xml

application.xml

.htaccessMLETs

login-config.xml

...

Ontology

Application Server Core Services

ComponentLoader

Security

TransactionManager

Naming

Administration

SecurityManagement

VersionManagement

Steffen Staab


KAON SERVER

http://kaon.semanticweb.org

• Prototype of an ontology-based Application Server

• Part of KArlsruhe ONtology and Semantic Web Toolsuite (KAON)

• Uses KAON ontology language and inference engine

• Makes obsolete several description files• Uses JMX/JBossMX• Inference engine as additional MBean• Additionally facilitates development

of Semantic Web applications[ACM TOIT 5(2)]

Steffen Staab


Relationship to MDA

• OMG‘s Model Driven Architecture

• Separates conceptual from implementation concerns

• Not applied for run time aspects so far

• Lack of formal semantics

• No reasoning capability

Steffen Staab


Agenda

• Application Server– Semantic Web for Application Server– App Server for Semantic Web

• Semantic Management of Web Services

Steffen Staab


Rule -b a se dsyste m

DLre a sone r

O nto lo g ySto re

XM L Sc he m aVa lid a to r

O nto log y Ed ito rPe rso n

G ra d ua te -Stud e nt Ac a d e m ic Sta ff

Pe rso n

b irthd a y

xsi:d a te Tim e

Porta l

Pe rso n G ra d ua te -Stud e nt Ac a d e m ic Sta ff

c o o p e ra te sWith(Y,X) < -> c o o p e ra te sWith(X,Y)

Info rm a tio n c ha in

APPLIC ATIO N

USES

SO FTWAREM O DULE

Analysis• Megaprogramming

• Semantic Web Layer Cake

Unicode URIXML + Namespaces

RDF + RDFS

OntologyLogic

ProofTrust

Steffen Staab


1. Flexible handling of modulesExtensibility, Dependencies, …

2. Static part of the Semantic WebLanguage Support, Ontology Mapping, …

3. Dynamic part of the Semantic WebFinding, Accessing, Modifying and Storing of ontologiesTransactions and Rollbacks, Evolution and Versioning, Inferencing and Verification, …

4. Semantic enhancement of the serverComponent capability descriptions and discovery, Semantic API descriptions, Component classification, automatic generation of semantic web service descriptions, etc.

5. Common Application Server functionality

Requirements

Steffen Staab


Requirements in the Architecture

Language Support

Semantic Interoperability

Ontology Mapping

Ontology Modularization

Finding, Accessing, Storing

Transactions, Rollbacks

Evolution, Versioning

Inferencing, Verification

Connectivity, Security

Extensibility

Discovery

Dependencies

Design element

Requirement Con

nect

ors

xxxxx

x x xx

x

x

Ker

nel

Reg

istr

y

Com

pone

ntL

oade

r

Ass

ocia

tion

Man

agae

men

t

Inte

rcep

tors

Func

tion

alC

ompo

nent

s

xxxx

xx x

x xx

Steffen Staab


Design1. Flexible handling of modules

→ Microkernel and component approach

Functionality: simple management operations (start, stop, monitor, ...)

Modules must be instrumented -> components

Microkernel

Compo

nent

. . .

So ftwa re M o d ule So ftwa re M o d uleInstrum e nta tio n

C o m p o ne nt

So ftwa re M o d ule Pro xyC o m p o ne nt

Exte rna lM o d ule

1)

2)Instrum e nta tio n

Steffen Staab


Design2. Static part of the Semantic Web

→ functional components

3. Dynamic part of the Semantic Web → functional components

4. Semantic enhancement of the server → ontological registry with inference capability → system component

5. Common Application Server functionality → Reuse existing Application Server as far as possible

Steffen Staab


ArchitectureClient

Surrogate1 Surrogate2

Steffen Staab


Implementation

Application Serverfor the Semantic Web

KernelComponents

Design

KAON SERVER MBeans MBeanServer

Implem

entation

Java Mgmt Extensions (JMX)

JBossMX

Steffen Staab


Starting the Server/Mgmt Console

Steffen Staab


Browsing and querying the registry

KAON OIModelerGeneric KAON ontology store surrogate

Steffen Staab


Browsing and querying the registryKAON OIModeller for browsing and querying the KAON SERVER‘s registry at run-time

Steffen Staab


OilEdOilEd

Reasoner surrogateGeneric RDF surrogate

KAO

N RD

F st

ore

S

esam

e

FaCT

Race

r

1. OilEd queries registryfor available reasoners

2. Component ID is fed intoreasoner surrogate

3. Reasoner surrogate relayscommunication to FaCT

Steffen Staab


From App Server to Web Services

ASSW Cascade

Steffen Staab


Purpose of Web Services

Semantic Web Web Services

helps

Semantic Web technology is useful for Web Services=Application Server + Wide Distribution + Web Standards

• Light-weight

• Widely distributed

• Heterogeneous platforms

Steffen Staab


Chasm of Web Services

Web Services Standards WS*

• RPC• I/O Typing• Workflow• Security• …

Plumbing

Semantic Web Services

• Goals• Means

End Customer Use

Steffen Staab


Chasm of Web ServicesSemantic Management of Web Services

Web Services Standards WS*

• Complex by size• Complex by

heterogeneity• No coherent model• Inconsistencies


• Too complicated to specify for developers

• Semantics not powerful enough

Steffen Staab


Costs


Management Costs

ModellingCosts

coarse fine

low

high TotalCosts

Modelling Cost Considerations

WS*

SWWS

Our target

Steffen Staab


Data vs Services Analogy

Data

• Modelling• Query• Modify• Join

Services

• Modelling• Query• Configure• Compose

• Execute • Monitor

Steffen Staab


Ordner A

Ordner B File 1 File 2

DBMS

Physical Data

Immediate Meaning of Data

Logical Schema

How?

What?

Why?Implicit Meaning of Data

Knowledge Discovery remains a labor-

intensive process!

Steffen Staab


KonkreteDefinitionen

referenziert

definitions

types

messagesparts

portTypeoperation

bindingoperation

serviceport

AbstrakteDefinitionen

Web Service MS

TCP/IP

„WS-Policy“, ….

WSDL, BPEL, …

How?

What?

Why?

(automatic composition!)


Service organisation will remain a labor-intensive process!

Steffen Staab


Conclusion from analogy

Modelling and use of Web services by manipulation of individual files is an archaic

practice – just like managing data by reading and writing individual files!

Steffen Staab


WS Management Objectives

• Separate „What?“ from „How?“

• Leave „Why?“ to the developer (at least for the moment)

• Go beyond simple data manipulation into semantic management in order to capture the immediate meaning of Web services

Steffen Staab


Use Cases

Who?

What for?

When?

Query type/Service Mgmt Task?

Steffen Staab


DOLCE

Descriptions & Situations

Ontology of Plans

Core Ontology of Services

Service Management Core Ontology

Domain ontologies

Ontologies for an Open World

Steffen Staab


D&S alignment to DOLCEGround entities of DOLCEDescriptive entities of D&S

Description

S-Description

Situation

played-by

satisfiesC-Description

Functional Role

Course

Parameter

component

In the following slides we see some modelling excerpts from the different levels…

Steffen Staab


COS alignment to D&SDOLCED&SCOS

Description

S-Description

Situation

Functional Role Course

Service AssessmentDescription

Service OfferingDescription

Service RequirementsDescription

Service ActivitiesDescription

Service AgreementDescription

Activity

Service Activity Computational Activity

AgentiveFunctional Role

InstrumentalityRole

Legally Constructed Person Executor

Requestor Provider

Input Output

Computational Input Comp. Output

Task

Service Task

Computational Task

InformationObject

Conceptual disambiguation

Wider scope

Steffen Staab


Service Management Core Ontology

Description Set of descriptiveconcepts and associations

AssociationDescriptiveConcept

Service Management DescriptionInformation

Source

Age of InformationParameter

Parameter

......

Quality of Service Descrip.

Plan Description

Interface DescriptionPolicy Description

Metadata from: WSDL, WS-policy, performace measurements, reflection

Steffen Staab


Policy Description

Situation

Descrip

tive En

titiesG

roun

d E

ntities

ComputationalActivity

ComputationalActivity

Perdurant

(non-agentive)Functional Role

InformationObject

InformationObject

Endurant

Task

Course of Event

participant

Constraint

valued-by

Constraint Value

obligation towardsanakastic duty towards

requisite for

ConcreteConstraint

ConcreteConstraint

User

(agentive)Functional Role

sequences

right

played-by

Object

InformationObject

InformationObject

Endurant

Parameter

played-by

Policy Constraint

Policy ConstraintConstraint Value

participant

locatedIn

Steffen Staab


Service Management Description SMD1

Interface Description ID1

Operation Op1

Computational Input CI1

Computational Output CO1

Service Management Description SMD2

Interface Description ID2

Operation Op2

Computational Input CI2

Computational Output CO2

<BPEL>

<WSDL> <WSDL>

Steffen Staab


Integration in KAON Server

Steffen Staab


Conclusion on Semantic Middleware

• Ontologies provide great practical benefit

• Conceptual difference between components and web services are marginal (see Oberle 2005)

• Ontologies are no silver bullet!– Problem: provision of semantic metadata

-> small is beautiful!

-> beautiful is cheap!

Steffen Staab


Thank You!• D. Oberle, A. Eberhart, S. Staab, R. Volz. Developing and Managing

Software Components in an ontology-based Application Server. In Proc. Middleware 2004, ACM/IFIP/USENIX International Middleware Conference, Toronto, October 18-22, 2004, LNCS, Springer.

• D. Oberle, S. Staab, R. Studer, R. Volz. Supporting Application Development in the Semantic Web. ACM Transactions on Internet Technology, 5(2), 2005.

• D. Oberle, S. Lamparter, A. Eberhart, S. Staab. Semantic Management of Web Services. Tech Report (shorter version at Semantic Web Service Week, Innsbruck June 2006).

• D. Oberle. Semantic Management of Middleware. Springer 2005/06

http://isweb.uni-koblenz.de/

Steffen Staab


Web services constitute a middleware in order to model distributed applications and let them run on a set of heterogeneous platforms. Unfortunately, the many different Web service standards do not include a formal, let alone a common formal, model, which would allow to give an integrated, consistent view onto all of them. In this talk we sketch how ontologies may be used to integrate metadata about middleware in general and web services, in particular. Thus, we may answer about properties of web services in order to facilitate the life of the system developer and administrator for managing complex, distributed systems.

steffen staab isweb – information systems & semantic web semantic management of web services...

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