ist-511607 mobilife – inter-wp meeting april 28, 2005slide 1 representing services for mobile...
TRANSCRIPT
IST-511607
MobiLife – Inter-WP meeting April 28, 2005 Slide 1
Representing Services for Mobile Computing using OWL and OWL-SAn Initial Investigation
Massimo Paolucci, Marko Luther and Matthias Wagner DoCoMo EuroLabs
Alessandra Andreetto, Walter Goix TILab
IST-511607
WSComp 05 September 2005 Slide 2
Services on the go
Services are ubiquitous in the environment
Simple services
Easy to model: provide a good test case for (S)WS technology
I need a ticket, my card # is 1234
Here is the ticket I charged your card
Ticketing Ticketing ServiceService
StopStopNotificationNotification
LandmarksLandmarks
News/InfoNews/Info
IST-511607
WSComp 05 September 2005 Slide 3
Challenges of Mobile Computing
• Working with services have a number of challenges– Discovery, Composition, Mediation, Security, Management, etc
• Mobile computing adds its own challenges– Limited resources
• Small devices, limited screen, limited power
– Unreliable network
• Wireless based networks are less reliable than line-based networks
• Some networks are limited in scope (bluetooth - WIFI)
• Multi Media data– Data exchanged is not just XML description of products
but it includes:
Music - Videos - Photos - Continuous voice and video streams
IST-511607
WSComp 05 September 2005 Slide 4
Essential Representation of Service Parameters
• Service parameters essential to the representation of capabilities of service– Service bandwidth
– Type of data transmitted
– Cost model
• Requirements on the terminal– Monitor size, CPU …
– Software requirements
• Browser
• Video viewer
• Policies and Privacy requirements
IST-511607
WSComp 05 September 2005 Slide 5
Requirements for Service Representation
• Represent capabilities of the service– The function that the service computes
– Quality of the service provided
• Represent service requirements– Resources requirements
• CPU, Screen size, Memory size, Network type and bandwidth
– Policies and Privacy requirements
– Cost models
• Use existing standards and emerging proposals– OWL, OWL-S
– CC/PP, UAProf
• Exploit context ontologies for the representation of application context and domain information
• Effectively computable logics: OWL DL
IST-511607
WSComp 05 September 2005 Slide 6
Approach
• Service Functionality– OWL-S
• Provide general schema to represent services• Provide description of functionality of the service
– Input/outputs preconditions/effects
• Service Taxonomies– Provide explicit description of classes of services
• Information services/ Personal communication services• Description of service parameters
• Service Requirements– CC/PP and UAProf
• Describe characteristics of the devices– Screen Size / CPU type– Software available
• Decidable logics: OWL DL
IST-511607
WSComp 05 September 2005 Slide 7
Methodology for selection of service parameters
• Extract list of services from Mockups – We extracted ~40 services
• Use these services to decide the features of the service representation– Test representation ideas on the 40 services (and natural
variations)– Relate to context ontologies
• With extensions when needed
IST-511607
WSComp 05 September 2005 Slide 8
OWL-S Service Profile
<profile rdf:ID="BravoAir">
<serviceName>BravoAir </serviceName>
<contactInformation rdf:resource="#BAco"/>
<serviceClassification rdf:resource="#Airline"/>
<product rdf:resource="#FlightReserv"/>
<serviceCategory rdf:resource="#NAICS_Airline"/>
<hasInput rdf:resource="#Dep_Airport"/>
<hasInput rdf:resource="#Arr_Airport"/>
<hasOutput rdf:resource="#Reservation"/>
<preconditions/>
<effects/>
</profile>
Who provides the service Type of service Product of the service
Classification inBusiness taxonomies
Typical inputs
Typical outputConditions that need to be satisfied for the service to run correctly
Conditions that result from the run of the service
IST-511607
WSComp 05 September 2005 Slide 9
MobiLife service ontology
• Explicit representation of service types
• Effective at specifying service specific parameters– Ex Entertainment services need
specification of type of content
IST-511607
WSComp 05 September 2005 Slide 10
Using Service Ontology:two problems
• Problems
1. The representation of services easily moves to OWL Full• Outside the power of many inference engines• Awkward representation
2. How does the service ontology integrate with OWL-S?
IST-511607
WSComp 05 September 2005 Slide 11
Problem 1:
Example of OWL Full
<owl:Class rdf:ID=”Info_Service”/>
<owl:property rdf:ID=”about”> <owl:domain rdf:resource=”#Info_Service”/> <owl:domain rdf:range=”owl:Thing”/></owl:property>
<Info_Service rdf:ID=”hotel_info_service”><about rdf:resource=”#Hotel”/>
</Info_Service >
Problem:about property of an instance
of service refers to the class Hotel
Mixing reasoning at instance and class level pushes logics to OWL full
IST-511607
WSComp 05 September 2005 Slide 12
Solution Problem 1:
Using anyURI type<owl:Class rdf:ID=”Info_Service”/>
<owl:DatatypeProperty rdf:ID=”about”> <owl:domain rdf:resource=”#Info_Service”/> <owl:domain rdf:range="&xsd;#anyURI"/></owl:DatatypeProperty >
Solution adopted in MobilOWL-S– Represent ranges as XML Schema URI
• Advantage: Logic stays in OWL DL
• Cost: these properties are outside DL reasoning, we need other reasoner
– Same solution adopted by OWL-S
– Similar to solution adopted by OWL Best practice Working Group
<Info_Service rdf:ID=”hotel_info_service”><about rdf:datatype="&xsd;#anyURI">
#Hotel </about></Info_Service >
IST-511607
WSComp 05 September 2005 Slide 13
Problem 2:
Service Ontologies and OWL-S
OWL-S at the rootHigh commitment: the whole service
ontology becomes OWL-S based
OWL-S at the leafsService instances are both OWL-S
and of some service typeLower commitment, but some
services may not be OWL-S based
OWL-S reference to service types OWL-S and service ontology totally disjoint
Limited use of OWL reasoning
ServiceService
CommerceCommerce CommunicationCommunication EntertainmentEntertainment
MusicMusic VideosVideos
Service ProfileService Profile
my Music Servicemy Music Service
Service ProfileService Profilemy Music Servicemy Music Service
Service ProfileService Profile
Accepted SolutionsOWL-S Profiles are OWL objects. They can be specialized to include additional service information
OWL-S Profiles are OWL objects. They can be specialized to include additional service information
IST-511607
WSComp 05 September 2005 Slide 14
Problem with OWL-S Service Parameters and Type
• OWL-S provides two properties:– ServiceParameters:
• Used to describe additional parameters of the service
• Redundant with OWL properties
– Service parameters can be defined as OWL properties
– Type
• Used to specify service type
• Redundant with OWL instance specification
– Service type can be specified by specializing the instance of OWL-S Profile
• Redundancies allow inconsistent specifications of OWL-S services
IST-511607
WSComp 05 September 2005 Slide 15
Inconsistency
<newsService rdf:ID=”NewsNow"> … <serviceClassification rdf:resource="#Airline"/>
…<communicationMode
rdf:resource="#realTime”>…<serviceParameter> <ServiceParameter> <serviceParameterName>
communicationMode </serviceParameterName> <sParameter
rdf:resource="#NonRealTime"/> </ServiceParameter></serviceParameter>…
</newsService>
Type inconsistency
ParameterInconsistency
This service profile is inconsistent but inference engines would not be able to detect the problem
This service profile is inconsistent but inference engines would not be able to detect the problem
IST-511607
WSComp 05 September 2005 Slide 16
Representation Dimensions(Still in Progress)
• Some Service parameters extracted– Communication_Channel
• Real time vs. non-real time/ SMS vs. SIP vs. Http• Streaming vs. conversational
– Target_Customers/ Content rating• Restrictions on the types of customers: who can access the service
– Media_Content• Video vs. audio vs. text vs. image vs. application
– Cost Model• Free vs. flat fee vs. per use
• Specialized Service parameters– Location-mode Parameter
• Cell-based - GPS based – Natural Language used
• Specify the language used by the interaction with the servic
IST-511607
WSComp 05 September 2005 Slide 17
An example
<MobilOWLS:Profile rdf:ID="a_Location_CP">
<profile:hasInput>
<process:Input rdf:ID="user">
<process:parameterType rdf:datatype="&xsd;#anyURI">
&agent;#Person
</process:parameterType>
</process:Input>
</profile:hasInput>
<profile:hasOutput>
<process:Output rdf:ID="user_location">
<process:parameterType rdf:datatype="&xsd;#anyURI">
&space;#Location
</process:parameterType>
</process:Output>
</profile:hasOutput>
<profile:serviceClassification rdf:datatype="&xsd;#anyURI">
&serviceOntology;#Location_Provider
</profile:serviceClassification>
<LocatinMethod rdf:datatype="&xsd;#anyURI"> http://…/space.owl#cell_id
</ LocatinMethod > <Communication_Channel rdf:datatype="&xsd;#anyURI">
http://…/Communication.owl#SMS
</ Communication_Channel>
</MobilOWLS:Profile>
IST-511607
WSComp 05 September 2005 Slide 18
Future Work
• Define mapping to cc/pp UAProf– Cc/pp provides language to specify terminal characteristics– UAProf provides a vocabulary defined on cc/pp for WAP terminals– Exists OWL ontology for cc/pp UAProf, but OWL Full
• How do we use MobilOWLS?– Define discovery algorithms
• What about other modules of OWL-S?– Should we change the Process Model?– Should we change the Grounding?
• Keep user in the loop– Discovery should be automated
…but user should be in control of which services are selected…and in control of the whole interaction process
IST-511607
WSComp 05 September 2005 Slide 19
Conclusions
• Service Parameters essential to represent services for Mobile Computing
• OWL-S + OWL provides enough expressivity to represent services– They represent both
• Functional aspect• Service Parameters
… butIt is necessary to remove redundancies in OWL-Sor to avoid representations that use those redundancies
• Hopefully MobilOWL-S will be available soon on semwebcentral.org