Folie 1

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Semantic Management of Web Services
Steffen Staab Prague May 19, 2005
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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

3
Hopes
Costs
high
RPC
WS
Management Costs
SWS
low
Granularity of Modelling
coarse
fine
4
Humbleness in Front of Total Costs
Costs
SWS
high
Total Costs
RPC
WS
Management Costs
Modelling Costs
low
Granularity of Modelling
coarse
fine
5
Humbleness

• What are the most urgent problems?
• Where are the largest benefits
• Analogy/Pseudoquote from Mohan (Sigmod Record,
  2004)

Where is this huge need for Semantic Web
Services? Better be incremental!
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.
6
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!
• Lets backtrack how!

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Situation AIFB 1999 not about Web Services
Portal3
Semantic Web Service x
...
Portal4
Semantic Web
External Internal
Portal1
Portal2
Knowledge Management App
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Contribution of this talk
Application Server for the Semantic Web
helps
Semantic Web
ASSW
helps

• ASSW facilitates application development in the
  Semantic Web
• Semantic Web technology is used within the ASSW

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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

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Problem
Complexity in Application Servers Multitude of
XML-DTDs
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Ontology

• 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

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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

...
Recommender- Servlet
WebShop- Servlet
Lib
Lib
...
News- Servlet
Lib
Lib
Customer Entity Bean
Lib
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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

...
Context Switch
Customer
WebShop- Servlet
Anonymous
Customer Entity Bean
Admin
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Ontology Design

• Ontology Design
• Syntactic vs. Semantic Metadata
• Generic vs. Domain Knowledge
• Modular

Container
Semantics of parameters Automatic generation
Capability Descriptions
Syntactic vs. Semantics
Domain Knowledge
Implementation details Mapping to source code
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Architecture
Ontology
...
web.xml
application.xml
login-config.xml
ejb-jar.xml
MLETs
.htaccess
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KAON SERVER

• 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 applicationsACM TOIT 5(2)

http//kaon.semanticweb.org
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Relationship to MDA

• OMGs Model Driven Architecture
• Separates conceptual from implementation concerns
• Not applied for run time aspects so far
• Lack of formal semantics
• No reasoning capability

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Agenda

• Application Server
• Semantic Web for Application Server
• App Server for Semantic Web
• Semantic Management of Web Services

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Analysis

• Megaprogramming
• Semantic Web Layer Cake

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Requirements

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

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Requirements in the Architecture
Association Managaement
Functional Components
Design element Requirement
Component Loader
Interceptors
Connectors
Registry
Kernel
x
x
Language Support Semantic Interoperability Ontolog
y Mapping Ontology Modularization Finding,
Accessing, Storing Transactions,
Rollbacks Evolution, Versioning Inferencing,
Verification Connectivity, Security Extensibility
Discovery Dependencies
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
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Design

• Flexible handling of modules ? Microkernel and
  component approach
• Functionality simple management operations
  (start, stop, monitor, ...)Modules must
  be instrumented -gt components

Microkernel
Component
. . .
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Design

1. Static part of the Semantic Web ? functional
   components
2. Dynamic part of the Semantic Web ? functional
   components
3. Semantic enhancement of the server ? ontological
   registry with inference capability ? system
   component
4. Common Application Server functionality ? Reuse
   existing Application Server as far as possible

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Architecture
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Implementation
Application Server for the Semantic Web
Kernel
Components
Design
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Starting the Server/Mgmt Console
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Browsing and querying the registry
KAON OIModeler
Generic KAON ontology store surrogate
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Browsing and querying the registry
KAON OIModeller for browsing and querying the
KAON SERVERs registry at run-time
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OilEd
OilEd

1. OilEd queries registryfor available reasoners
2. Component ID is fed intoreasoner surrogate
3. Reasoner surrogate relayscommunication to FaCT

Reasoner surrogate
Generic RDF surrogate
KAON RDF store
Sesame
FaCT
Racer
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An Example
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An Example (continued)
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An Example (continued)
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Transaction Interceptor
Other

Local
RMI
Web Service
System Component
Connectors
Interceptor
Functional Component
Proxy Component
Registry
Association Management
Kernel
Management Core
Interceptors
Transaction
Functional Components
Ontology Store Customers
Ontology Store Hotels
Web service Proxy
Car rental web service
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KAONPortal
Client X

OI-Modeller
TextToOnto
Open Registry

KAON Workbench
KAON API

• Lexica

• Transactions
• Modularisatiuon

• Evolution
• Metamodelling

KAONQuery, Datalog
API Proxy
web
API on RDF
Engineering Server(direct, local, remote)
KAON RDF API
Main-Memory
RDF-Server
XML
RDBS
RDBS
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From App Server to Web Services
ASSW Cascade
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Purpose of Web Services

• Light-weight
• Widely distributed
• Heterogeneous platforms

helps
Semantic Web
Web Services

• Semantic Web technology is useful for Web
  ServicesApplication Server Wide
  Distribution Web Standards

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Chasm of Web Services

• Web Services Standards WS
• RPC
• I/O Typing
• Workflow
• Security
• Plumbing

• Semantic Web Services
• Goals
• Means
• End Customer Use

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Chasm of Web Services

• Web Services Standards WS
• Complex by size
• Complex by heterogeneity
• No coherent model
• Inconsistencies

• Semantic Web Services
• Too complicated to specify for developers
• Semantics not powerful enough

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Modelling Cost Considerations
Costs
SWWS
high
Total Costs
Our target
WS
Management Costs
Modelling Costs
low
Granularity of Modelling
coarse
fine
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Data vs Services Analogy

• Data
• Modelling
• Query
• Modify
• Join

• Services
• Modelling
• Query
• Configure
• Compose
• Execute
• Monitor

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DBMS
Knowledge Discovery remains a labor-intensive
process!
Implicit Meaning of Data
Why?
Immediate Meaning of Data
What?
Logical Schema







Physical Data
How?
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Web Service MS
Service organisation will remain a
labor-intensive process!
Semantic Web Services
Why? (automatic composition!)
WS-Policy, .
What?
WSDL, BPEL,
TCP/IP
How?
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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!

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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

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Use Cases
Who? What for? When? Query type/Service Mgmt Task?
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Ontologies for an Open World
DOLCE Descriptions Situations
Ontology of Plans Core Ontology of Services
Service Management Core Ontology
Domain ontologies
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DS alignment to DOLCE
Ground entities of DOLCE Descriptive entities of
DS
In the following slides we see some modelling
excerpts from the different levels
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COS alignment to DS
DOLCE DS COS
Situation
Description
S-Description
Functional Role
Course
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Service Management Description
Information Source
Computational Input
Age of Information
Age of Information
Security Stuff ?
...
Descriptive Entities
Parameter
Functional Role
successor
Task
Age of Information
Computational Output
Age of Information
Age of Information
Age of Information
...
Parameter
Functional Role
Course of Event
played-by
sequences
valued-by
Situation
Computational Activity
URL
Ground Entities
participant
Information Object
Temporal Region
Perdurant
Region
Endurant
Region
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Service Management Core Ontology
Metadata from WSDL, WS-policy, performace
measurements, reflection
Set of descriptive concepts and associations
Descriptive Concept
Description
Association
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Policy Description
Constraint
requisite for
Parameter
Task
User
right
Descriptive Entities
anakastic duty towards
Object
obligation towards
Course of Event
(agentive) Functional Role
(non-agentive) Functional Role
valued-by
sequences
played-by
played-by
Computational Activity
Policy Constraint
participant
Information Object
Perdurant
Constraint Value
Ground Entities
Information Object
participant
Endurant
locatedIn
Concrete Constraint
Endurant
Situation
Constraint Value
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Service Management Description SMD1
Service Management Description SMD2
Interface Description ID1
Interface Description ID2
ltBPELgt
Operation Op1
Operation Op2
Computational Input CI1
Computational Output CO1
Computational Input CI2
Computational Output CO2
ltWSDLgt
ltWSDLgt
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Integration in KAON Server
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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
• -gt small is beautiful!
• -gt beautiful is cheap!

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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/
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• 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.