Services in Ubiquitous Computing

1
Services inUbiquitous Computing

• Infrastructure, Tools and Ontologies

Daniel Elenius ltdaele_at_ida.liu.segt
2
Overview of presentation (1/4)

• Part I - Background (15 min)
• What are services?
• What is ubiquitous computing?
• What are the research issues?

3
Overview of presentation (2/4)

• Part II - Infrastructure (15 min)
• Existing infrastructures
• Requirements
• The Oden architecture

4
Overview of presentation (3/4)

• Part III - Tools (10 min)
• Existing tools
• Requirements
• The OWL-S Editor

5
Overview of presentation (4/4)

• Part IV - Ontologies (10 min)
• What are they?
• What should we describe?
• How should we describe it?
• Global or local ontologies?

6
Part I - Background
7
Services - some definitions
Business model layer (value exchanges)
Service (business science)
Business process layer (business processes)
E-Service (information science)
Technical process layer (processes implemented
using IT)
Web Service (computer science)
Information systems layer (applications, software
components)
8
Web Services

• WSDL
• An interface definition language
• SOAP
• An invocation protocol/format
• UDDI
• A service registry

9
Semantic Web Services

• The Semantic Web
• The vision
• Use cases
• RDF
• OWL
• Semantic Web Services
• OWL-S

10
OWL-S

• Goals
• Automated or simplified interactions
• Human-machine
• Machine-machine
• Tasks
• Discovery
• Invocation
• Composition
• Monitoring

11
OWL-S

• Service
• Holds the parts together
• Profile
• Advertisement
• Non-functional properties

12
OWL-S

• Process
• Functional properties
• Inputs
• Outputs
• Preconditions
• Effects
• Atomic processes
• Composite processes
• Grounding

13
OWL-S
Service
supports
presents
described by
How to access it
Profile
Grounding
Process
What the service does
WSDL Grounding
How it works
Programming interface
14
Another approach - BPEL4WS

• Also composition and invocation
• In addition
• Exceptions
• Industry support
• But
• Assumes pre-defined composition
• No reasoning
• No domain ontologies

15
Ubiquitous Computing

• Ubiquitous everywhere
• Smaller, cheaper, faster devices
• Pervasive/Invisible/etc.
• New forms of HCI
• New challenges for Services
• Not just web services!

16
Part II - Infrastructure
17
Peer-to-Peer and UbiComp

• Mobility
• Changing network addresses
• Changing network topology
• Changing availability of services
• Reliability
• No server as single point of failure

18
JXTA

• P2P Technology developed by Sun
• Juxtapose Side by side
• Open Source www.jxta.org
• Language independent
• J2SE Reference Implementation
• J2ME, C, C, Ruby, Perl versions
• Transport independent
• TCP, HTTP available
• Other transports possible

19
JXTA

• Abstracts network details and communication
• Peers
• Peer groups
• Advertisements
• Pipes
• Very open many things unspecified

20
Service Discovery

• What service do we need?
• Where can we find it?
• How do we find it?
• How can we evaluate services?
• How can we use services (invocation)?

21
Service Discovery
22
Goals for this project

• Extending JXTA with Service Discovery (and
  Service Invocation)
• Description OWL-S and WSDL
• Reasoning JTP
• Invocation SOAP
• Not for embedded implementation, just
  proof-of-concept
• Runs on networked PCs (or just one PC)

23
What needed to be done

• Decide how WSDL and OWL-S descriptions are to be
• Discovered
• Shared
• Evaluated
• Decide how services are to be invoked
• Write code for this architecture

24
Peers and their advertisements
25
Negative Results

• XML formats and logical inference reasoning
  heavyweight but flexible
• OWL-S overly verbose
• Automated tools may help
• Difficult keeping files in sync

26
Positive Results

• Platform independent communication between JXTA
  peers
• Advanced service discovery for JXTA
• Demonstration GUI

27
Future work

• More complex devices
• Ontologies representing context of discovery
• Different peer groups to represent different
  locations
• Automatic GUI generation

28
Part III - Tools
29
Tools for Services in UbiComp

• Simulation
• Development
• Domain ontologies
• Semantic web services

30
Protégé

• An Ontology Editor
• Developed by Stanford
• Open source
• http//protege.stanford.edu/index.html
• Wide base of users and developers
• Extendable plugin architecture

31
(No Transcript)
32
The OWL-S Editor

• New project to create a Protégé plugin
• Daniel Elenius, Linköping University
• SRI (Stanford Research Institute), Palo Alto
• Support for editing OWL-S in Protégé
• Searching
• Consistency checking
• Automatic instance generation
• Graphical editor for composite processes

33
(No Transcript)
34
Part IV - Ontologies
35
Ontologies

• Ontology or ontologies?
• Philosophy
• The basic categories of reality/our cognition
• Information Science
• an explicit specification of a conceptualization
  of a domain?
• E.g. an ontology of the domain of services -
  OWL-S.

36
Ontologies

• Some features of ontologies
• Classes/Concepts
• Instances/Individuals
• Properties/Relations
• Constraints

37
Top-level Ontologies

• A fusion Top-level ontologies
• Clear ontological commitments
• Translation between ontologies
• Integration of disparate data sources

38
An example The Generalized Upper Model
Um-thing
Configuration
Sequence
DoingHappening
BeingHaving
Expanding-Sequence
Projecting-Sequence
Element
SayingSensing
Simple-Quality
Process
Simple-Thing
Circumstance
Participant
39
Ontologies

• Ontological Engineering
• Experiences from OO-, ER-modeling, etc.
• Global ontologies
• CYC/OpenCYC

40
Thank you!