eswc ss 2012 - tuesday keynote john domingue: services, semantics and linked data
TRANSCRIPT
Services, Semantics and Linked Data
John DomingueKnowledge Media Institute, The Open University & STI International
Agenda• Software and Services• A Short History of Semantic Web Services • Linked Data Effect• Rise of REST• Linked Data and Services• Example Applications• Current and Future W3C work• Summary
SOFTWARE AND SERVICES
Software• Slow to produce!
–10 lines of code per day
• Code is ubiquitous –Car has 2 million lines of code
(8,000 Person Years)–Windows XP 45 million lines of code
(180,000 Person Years)
• Reusability is important
Service (economic)• Intangible commodity
–Consulting, childcare, educational• Tertiary sector of the economy
–Provision of value-adding services –Complementing
• secondary sector manufacturing and• primary sector: agriculture, fishing, mining …
–63% of Global GDP $44 trillion
Service (computational)
Web Service Usage Process• Deployment
– create and publish Web service description• Discovery
– determine usable services for a task• Composition
– combine services to achieve a goal• Selection
– choose most appropriate service• Mediation
– solve mismatches (data, protocol, process) that hamper interoperation
• Execution– invoke Web services following programmatic conventions
Web Service Execution Support• Monitoring
– control the execution process
• Compensation– provide transactional support and undo
or mitigate unwanted effects
• Replacement– facilitate the substitution of services by
equivalent ones
• Auditing– verify that service execution occurred in
the expected way
WSDL
WSDL Simplified
Web service
Operation 1
Operation 2
Operation N
input
input
input
output
output
output
...+-
A SHORT HISTORY OF SEMANTIC WEB SERVICES
OWL-S
Ontology images compliments of Terry Payne, University of Southampton
Service Profile (partial)
Class Hierarchies of ServicesServiceProfile
ProductProvidingService
Manufacturing
Transportation
ActionService
InfoService
PhysicalProductService Repair
information-Product+
physicalProduct+manufacturer+
deliveryRegion*deliveryProvider*
deliveryType
physical-Product+
transportationMode+geographicRegion+
physicalProduct+
Tie in with UNSPSC, etc.DL Basis for matchmakingMultiple profiles; multiple hierarchies
nameprovider
avgResponseTime?… FeeBased feeBasis+
paymentMethod+
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Objectives that a client may havewhen consulting a Web Service
Provide the formallyspecified terminologyof the information usedby all other components
Semantic description of WebServices: - Capability (functional)- Interfaces (usage)
Connectors between components withmediation facilities for handling heterogeneities
WSMO Top-level Elements(http://www.wsmo.org)
Web ServiceImplementation
(not of interest in Web Service Description)
Choreography --- Service Interfaces ---
Capability
functional description
WS
WS
- Advertising of Web Service- Support for WS Discovery
client-service interaction interface for consuming WS - external visible behavior- communication structure - ‘grounding’
realization of functionality by aggregation- functional decomposition - WS
composition
Non-functional Properties
DC + QoS + Version + financial
- complete item description- quality aspects - Web Service
Management
WS
Orchestration
WSMO – the Web service element
Semantic Web Service Broker
Client
Services
VTA
VTA WS ‘Trip Booking’
Capability
provides
Chor.Interf.
Flight Request
Hotel Request
Book Flight
Book Hotel
if hotel = Ø flight.arrivaltime = hotel.arrivaltime
flight information
if flight = Ø
hotel information
process (control + data flow) of goals
Orchestration Definition
VTA
VTA WS ‘Trip Booking’
Capability
provides
Chor.Interf.
Flight Request
Hotel Request
Book Flight
Book Hotel
if hotel = Ø
if flight = Ø
process (control + data flow) between “states” + communication behavior of orchestrating Web Service
Flight WS
Capability
Interface (Chor.)1) get request2) provide offer 3) receive selection4) send confirmation
Orch. ..
Hotel WS
Capability
Interface (Chor.)1) get request2) provide offer 3) receive selection4) send confirmation
Orch. ..
flight request
avaiable flights
hotel request
avaiable hotels
book request booking confirmation
book request
booking confirmation
Runtime Orchestration
LINKED DATA EFFECT
25 Billion Statements
Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net
How?
Data.gov.uk Applications
RISE OF REST
RESTful Service
• Lightweight compared to SOAP/WSDL• Use HTTP methods explicitly (GET, POST, PUT,
DELETE)• Stateless• Expose directory structure-like URIs• Data transfer using XML, JavaScript Object Notation
(JSON), or both.
RESTful Service Takeup
1876 APIs
4736 Mashups
REST vs SOAP API Searches
http://www.google.com/insights/search/#q=soap%20api%2Crest%20api&cmpt=q
LINKED DATA AND SERVICES
Linked Open Services
http://www.linkedopenservices.org/
MicroWSMO & WSMO-Lite
37
WSDL
39
SAWSDL
But:no predefined semantics!
40
WSMO-Lite in WSDL
MicroWSMO• Built on top of hRESTS which introduces the
service model structure on Web pages–service (+ label)–operations (+ address, method)–input, output
• MicroWSMO extends hRESTS–model, lifting, lowering
• Applies WSMO-Lite semantics
41
MicroWSMO
MicroWSMO
Service
OperationInput
Parameter
MicroWSMO
Service
OperationInput
Parameter
MicroWSMO
46
Minimal Service Model
Service Template
47
RDFS/WSML-Core taxonomy e.g., ServiceFinder
ServiceTemplate
hasInput
hasOutput
hasFunctionalCategory
hasPreference
hasRequirement
RDF-based domain ontologye.g., RDFS/WSML-core, OWL/WSML-DL, WSML-Rule
RDFS/WSML-Core preference modele.g., WSMO Pref, U-Sevilla
WSMO-Lite annotatione.g., Condition, Effect WSML Flight/Rule
logical expression
RDF-based context ontologye.g., RDFS/WSML-core, OWL/WSML-DL, WSML-Rule
hasContextualSens.
Deployment
Process Editor
Discovery
Service Lifecycle
ServiceAnnotation
Process Modeling
Process Execution
Analysis & Monitoring Invocation
Resource-Orientation (ROSM)
49
ServicedResource
ServicedResourceCollection
Service
Operationsupports
Method
ResponseCode
HTTP *
* http://www.w3.org/2006/http#
basedOn
Request Response
Parameter
Optional Parameter
Required Parameter
1 2
1. requestURIParameter requestBodyParameter requestHeaderParameter
2. hasBody
collects
EXAMPLE APPLICATIONS
Example 1: House Hunting …
… public transport …
… schools
www.tauntonschool.co.uk
Behind the Scenes
Train stations
Bus stops
Schools
Real estate
Public Data and Services
publishingService Broker
Invocation Engine
discovery
invocation
CURRENT AND FUTURE WORK
The Future Internet – Enabler for Global Business Networks
Manu-facturing
UrbanManagement
eEnergyTransportLogistic
….
Network of the Future
Cloud Computing
Internet of Things
Internet of Services
Internet of the Future
Consumers
Suppliers
Wholesalers
RetailersCarriers
Manufacturer
Governments
© SAP 2010 /
The Internet of Services – Global Service Delivery Supply Chain
A Single Market for Services
SaaS, On-DemandEnterprise Suites
Cloud Services
ServiceMarketplaces
Multi-Enterprise Business process
platforms
B2B Gateways
Business ProcessOutsourcing
Business Process Platform
Service Delivery FrameworkService
AggregatorServiceHoster
ServiceProvider
ServiceGateway
ServiceBroker
ServiceChannel Maker
Service-Oriented Architecture
© SAP 2010 /
ServiceAggregator
ServiceHoster
ServiceProvider
ServiceGateway
ServiceBroker
ServiceChannel Maker
The Internet of Services – Unified Service Description Language (USDL)
Service Transformation stands for a value-driven, smooth and effective provision of services along the Global Service Delivery Supply Chain
Service Transformation implies that Services are being Described considering business, operational and legal requirements Maintained, extended and assembled where needed Applying a common notation named USDL
© SAP 2010 /
W3C USDL Incubator
http://www.linked-usdl.org/
This group is based on the idea of combining two Web-related concepts to help solve some of the long-standing challenges involved in building and combining software:
1. RDF, the Resource Description Framework…. RDF is the basis for Linked Data and the Semantic Web.
2. With RESTful APIs and RESTful Web Services, ….
The Linked Data Platform is envisioned as an enterprise-ready collection of standard techniques and services based on using RESTful APIs and the W3C Semantic Web stack
Summary• Web services successful history in corporate settings
–Supporting reuse of software components• Semantic Web services
–Lots of research–Takeup limited
• New trends–RESTful services–Linked Data portals/applications
• Manage applications which make use of these trends
• Fit to the goals, needs and contexts of users
Acknowledgements