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© Copyright 2016‐2018 Anna Fensel
Semantic Web Services
SS 2018
Linked Services
Anna Fensel
04.06.2018
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Where are we?
# Title
1 Introduction
2 Web Science + Cathy O’Neil’s talk: “Weapons of Math Destruction”
3 Service Science
4 Web services
5 Web2.0 services
6 Semantic Web + ONLIM APIs (separate slideset)
7 Semantic Web Service Stack (WSMO, WSML, WSMX)
8 OWL-S and the others
9 Semantic Services as a Part of the Future Internet and Big Data Technology
10 Lightweight Annotations
11 Linked Services
12 Applications
13 Mobile Services

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Outline
• Motivation
• Minimal Service Model (MSM)
• Linked Services
• Linked Service Systems
• USDL and LinkedUSDL
• Summary
• References
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MOTIVATION

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Motivation for Linked Services
• Availability of Linked Data enabled its practical application in service
modeling
• “Data as a service” trend
• More advanced and flexible interlinking of services
• Step beyond WSMO, OWL-S, etc. solutions, towards simplification
• Meeting business needs (in particular, USDL and LinkedUSDL)
…actively developed starting ca. 2010 till the current days.
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MINIMAL SERVICE MODEL
(MSM)

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MSM – What it is
• The most well-known approaches to annotating services semantically
are OWL-S, WSMO, SAWSDL, WSMO-Lite when it comes to WSDL
services, and MicroWSMO, and SA-REST for Web APIs.
• In order to cater for interoperability, iServe uses what can essentially be
considered the maximum common denominator between these
formalisms which we refer to as the Minimal Service Model (MSM).
• The MSM, first introduced together with hRESTS and WSMO-Lite, is
thus a simple RDF(S) ontology able to capture (part of ) the semantics
of both Web services and Web APIs in a common model supporting the
common publishing and search of services while it allows specific
extensions to benefit from the added expressivity of other formalisms
should tools and applications require it.
Source - iServe project: http://kmi.github.io/iserve/latest/project-info.html
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MSM – Ontology depiction
Source – iServe project: http://kmi.github.io/iserve/latest/project-info.html

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MSM explanation
• MSM characterises Services as being composed of a number of Operations,
which in turn have input, output and fault MessageContent descriptions.
MessageContent may be composed of mandatory or optional
MessageParts.
• The model is complemented by the WSMO-Lite vocabulary, which denes
classes for describing the four core aspects of service semantics identified by
previous research on service semantics, namely, functional semantics,
nonfunctional semantics, behavioural semantics, and an information model.
These types of service semantics are relevant for advanced discovery,
selection and composition, among other tasks.
• The main classes of WSMO-Lite are Condition, Effect, and
FunctionalClassicationRoot, used for capturing functional and behavioral
semantics, and NonfunctionalParameter for nonfunctional semantics.
• To attach the semantics to the service model, we use the RDF mapping of
SAWSDL, which denes three properties, namely modelReference,
liftingSchemaMapping and loweringSchemaMapping.
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LINKED SERVICES
FOR THIS PART, FOLLOW PRESENTATION OF J. DOMINGUE & C.
PEDRINACI: “LINKED SERVICES: CONNECTING SERVICES TO THE
WEB OF DATA”,
HTTP://WWW.SLIDESHARE.NET/JOHNDOMINGUE/LINKED-
SERVICES-CONNECTING-SERVICES-TO-THE-WEB-OF-DATA

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LINKED SERVICE SYSTEMS
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Understanding Check / Exercise 1
Introducing Linked Service Systems
• What is a service system?
(Remember the service system characteristics discussed in Lecture 3 – Service
Science.)
• Which questions you would need to ask to learn about it?
• And how can a Linked Service System be modeled?
• … the answers are drafted on the next slides.

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Linked Service Systems
(also: General positioning of USDl and Linked
USDL)
Source: Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014. ISBN 978-3-319-10813-1.
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Linked Service System (LSS) Model Structure
Source: Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014. ISBN 978-3-319-10813-1.

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LSS Implementation Example - Goals
Source: Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014. ISBN 978-3-319-10813-1.
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LSS Implementation Example - Locations
Source: Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014. ISBN 978-3-319-10813-1.

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LSS – Service views
Commonly applied, also in tools e.g. graphical editors:
Source: Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014. ISBN 978-3-319-10813-1.
- interactions, internal
interactions
- bill of materials, resources
- map, location, geo
- project management view
e.g. people’s involvement
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Understanding Check / Exercise 2
• Describe in an LSS manner a logistics or a transport service system
– With multiple service providers
– With multiple service types
– With service consumers having various goals
• Find linked data sets that can be relevant for your use case
• Ask other team or colleague to formulate goals in order to interact with
your system, and see how easy/difficult it is to address the goals.
Where are the difficulties?
• Elaborate on how to relate LSS to other service-related technologies
(linked data, WSMO, schema.org actions, etc.). Where are the highest
application added value potentials?

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USDL & LINKED USDL
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USDL – What it is
• Initiated at W3C in 2010-2011
– “The mission of the Unified Service Description Language Incubator
Group is to define a language for describing general and generic parts
of technical and business services to allow services to become tradable
and consumable.”
• Incubator group summary:
https://www.w3.org/2005/Incubator/usdl/
• There the first USDL specification was produced
• Industrially backed by SAP
• Developments have been also referred as “Internet of
Services”

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LinkedUSDL – What it is
See also: https://github.com/linked-usdl
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USDL and LinkedUSDL - Overview
For introduction and overview to USDL and LinkedUSDL, follow
presentation of J. Cardoso: “Linked-USDL”,
http://www.slideshare.net/JorgeCardoso4/l07-linkedusdl

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Understanding Check / Exercise 3
Model the key services of your LSS from Exercise 2 using
LinkedUSDL.
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SUMMARY
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Conclusions
• MSM aims to simplify and minimalise the service models developed by
now, and provides a minimalistic ontology.
• Linked Services are connecting (linked) data with services; iServe is
one of its main implementations.
• Linked Service Systems provide a modeling environment to
semantically model service systems, employing linked data.
• USDL is a language for modeling services from a business point
perspective;
• LinkedUSDL is an instance of USDL employing linked data and having
a semantic representation.
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REFERENCES
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References
• Jacek Kopecký, Karthik Gomadam, Tomas Vitvar: hRESTS: an HTML
Microformat for Describing RESTful Web Services. In Proceedings of
the 2008 IEEE/WIC/ACM International Conference on Web Intelligence
(WI-08), December 2008, Sydney, Australia.
• Pedrinaci, C., Kopecký, J., Maleshkova, M., Liu, D., Li, N., & Domingue,
J. (2011). Unified lightweight semantic descriptions of web apis and
web services.
• Cardoso, J., Lopes, R., Poels, G. “Service Systems”, Springer, 2014.
ISBN 978-3-319-10813-1.
• LinkedUSDL: http://www.service-oriented-computing.de/linked-usdl.php
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Next Lecture
# Title
1 Introduction
2 Web Science + Cathy O’Neil’s talk: “Weapons of Math Destruction”
3 Service Science
4 Web services
5 Web2.0 services
6 Semantic Web + ONLIM APIs (separate slideset)
7 Semantic Web Service Stack (WSMO, WSML, WSMX)
8 OWL-S and the others
9 Semantic Services as a Part of the Future Internet and Big Data Technology
10 Lightweight Annotations
11 Linked Services
12 Applications
13 Mobile Services

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Questions?