=Paper=
{{Paper
|id=None
|storemode=property
|title=Towards Semantic TV Services - A Hybrid Semantic Web Services Approach
|pdfUrl=https://ceur-ws.org/Vol-623/paper06.pdf
|volume=Vol-623
}}
==Towards Semantic TV Services - A Hybrid Semantic Web Services Approach==
https://ceur-ws.org/Vol-623/paper06.pdf
Towards semantic TV services
a hybrid Semantic Web Services approach
Bassem Makni, Stefan Dietze, and John Domingue
Knowledge Media Institute, The Open University
Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
{b.makni,s.dietze,j.b.domingue}@open.ac.uk
http://kmi.open.ac.uk
Abstract. We are investigating the current Semantic Web Services ap-
proaches in order to select the most appropriate approach to build se-
mantic internet TV services. Two major approaches are prominent which
are top-down and bottom-up approaches, the former being heavyweight
and supporting complex reasoning tasks and the latter being lightweight
with limited reasoning capacity. We defend our assumption that seman-
tic TV services require the strengths of both approaches and introduce
a novel hybrid approach.
Keywords: Semantic Web Services, WSMO, IRS-III, Minimal Service
Model, iServe, Hybrid Semantic Web Services approach
1 Introduction
Nowadays, we share our knowledge via Wikipedia, our videos via Youtube, our
profiles via Facebook, what we are doing via Twitter and our leisure time via
Second Life. One of the last entertainment media, which endured resistant to co-
operation and interactivity, was TV where the user was still a passive consumer.
However the TV concept has evolved recently from the classic sofa TV to mobile
and hybrid TV. This evolution has benefited from the bandwith increase and
smart phones wide spread use. Just like the Web content expansion phenomena,
the evolution was coupled with the scattering of TV and multimedia content,
where the user struggles to find a relevant content, which perplexes the leisure
time. Hence the need for new TV features : social, interactive, personalised and
semantic. Such an ambitious idea requires many contributors to provide mul-
timedia content, enrich the metadata with semantics, propose recommendation
systems and build social networks around TV preferences. The NoTube1 project
gathers many partners around the semantic TV idea. As a first step towards
collaboration, these partners expose their services via web services endpoints,
that, in our vision, should be followed by a brokerage approach mainly aiming
at the automation of Web service related tasks such as discovery, orchestration
and mediation.
1
www.notube.tv
2 Makni et al.
2 Problem statement
The actors in the semantic TV challenges, such as content producers, semantic
enricher and recommender, have different backgrounds and concerns, which lead
to a highly diversified state on choices of paradigms and technologies with three
aspects of diversity:
Different multimedia metadata schemas Content producers tend to main-
tain the format they are already using, as converting their whole multimedia
base is expensive and need new expertise. Within NoTube, the main schemas
being used are MPEG7, TV-Anytime2 and Electronic program guides (EPG)
implying higher complexity on content processing.
Diverse tasks The exposed services achieve diversified tasks from content pro-
cessing such as transcoding, scaling, cropping, to profile analysis and meta-
data semantic enrichment.
Multiple services approaches Moreover, the partners expose their services
via multiple means such as Web API, REST [4] or SOAP3 services.
In a such highly fragmented state, Web services tasks such as services selection,
composition, mediation and orchestration, obviously require minimal level of au-
tomation. However the restricted machines vision of web services as inputs and
outputs, without any consciousness, hinders the automation of these tasks. For
instance, messages containing a compression rate from a video compression ser-
vice or a weight for a recommender service, are syntactically equivalent. Hence
the necessity of processing the services messages and operations at the semantic
level via shared ontologies. Therefore the past decade has seen a wide range
of research efforts in the area of Semantic Web Services (SWS), mainly using
semantic annotations in order to automate the mentioned tasks. We split the
yield of these efforts into top-down and bottom-up approaches. Actually both
approaches are used separately within the NoTube project to semantically an-
notate the contributors services, specifically a WSMO [8] based approach and
a Linked Service [7] approach. We briefly introduce each approach with their
respective implementations, IRS-III [2] and iServe [7], discuss the reasons of
their insufficiency to solve the semantic TV challenges individually, and defend
our motivation for a novel hybrid approach that combines the strengths of both
approaches.
2.1 Top-down Semantic Web Services approaches
Top-down approaches provide conceptual frameworks and languages, such as
OWL-S [6] and WSMO, to describe the semantics of web services before ground-
ing these descriptions to the services. A considerable research community evolved
around these SWS frameworks, providing, for example, annotation and execution
2
http://www.tv-anytime.org/
3
http://www.w3.org/TR/soap/
Hybrid Semantic Web Services approach 3
tools based on these formal SWS frameworks. For instance IRS-III is a seman-
tic execution environment that adopts the WSMO approach, videlicet that a
service description is expressed in terms of Goals, Mediators, Web Services and
Ontologies. IRS-III supports capability-based invocation: the request is a goal
to be achieved via the following intermediated operations [2]
1. discover potentially relevant Web services;
2. select the set of Web services which best fit the incoming request;
3. mediate any mismatches at the conceptual level;
4. invoke the selected Web services whilst adhering to any data, control flow
and Web service invocation constraints.
Formalising these operations requires the use of rich knowledge representation
languages and complex reasoners. However, the need to capture comprehensive
and meaningful service semantics to allow reasoning-based automation of web
services related tasks, contrast the requirement to lower the costs for providing
services descriptions in order to simplify the modeling process for non SWS
experts.
2.2 Bottom-up Semantic Web Services approaches
Based on the dictum that the top-down approach assumption, that the service
engineer describes semantics for the service before grounding these descriptions
to the services, is counter-intuitive, the bottom-up approach builds incremen-
tally upon existing Web services standards. Bottom-up or ’lightweight’ SWS
approaches such as WSMO-Lite [9] or the Micro-WSMO/hRESTs [5] approach
use less comprehensive and less costly service models. This approach was re-
cently dubbed Linked Service approach [7] by analogy to the Linked (Open)
Data (LOD) term [1] as it reuses the lessons learnt from the Web of data in
the services field, in order to facilitate the service annotations production and
thus addressing a much wider audience and allowing even non-SWS experts to
describe and annotate services. iServe adheres to the Linked Services approach
and provides seamless publication and discovery of services by transforming ser-
vice annotations expressed in a variety of formats into Linked Services data
describing services and processable by the Semantic Web technologies. Services
are expressed in terms of a simple conceptual model, the Minimal Service Model
(MSM), conceived to be the largest common denominator between various an-
notating approaches formalisms to ensure interoperability.
However, while those models are easier to produce [3], they merely aim at
enabling structured, semantics-enabled search by humans or automated service
clustering, and more expressive solutions are required to achieve greater levels
of automation when carrying out tasks such as the fully automated discovery or
orchestration of services.
3 Main questions of the thesis
But we enquire about : the real need of this automation, what are the most im-
portant tasks to be automated, their feasibility, the worth estimation compared
4 Makni et al.
to the investment cost, the benefits of an hybrid approach, could it maintain
lower annotation costs while providing higher level of reasoning and how.
4 General approach
The actors in the semantic TV challenges are rarely SWS experts, and therefore
adopt the handy approach, namely Linked Services to annotate their services.
However brokering such diversified and complex services as TV recommender
and TV social services requires more exhaustive descriptions of the services and
complex reasoning. Hence we aim to combine the strengths of both distinctive
approaches into a coherent SWS framework.
5 Proposed solution
As a first step towards hybridization we investigated top-down and bottom-up
approaches in order to predict the feasibility and cost of our approach. We sketch
in Figure 1 a conceptual comparison between WSMO and MSM to evaluate the
overlaps and differences between both.
6 Evaluation
As we predicted there are a few overlaps, Web service and Ontology. WSMO high
level concepts such as Goal and Mediator have no equivalent in MSM, likewise
the Operation concept in MSM is omitted in WSMO as it uses more abstract
concepts such as Choreography. However we dressed functional similarities in the
properties that we drew close, such as has-condition and has-assumption, has-
effect and has-postcondition. Besides many concepts model close notions such
as Capability and Functional classification, Method and Choreography. Since the
ambition for a possible interoperability between both approaches.
7 Future work
We will pursue our models investigation by a translation mechanism to allow
IRS-III and iServe annotations interoperability.
8 Conclusion
In a highly complex and fragmented services pool such as the TV services, nei-
ther heavyweight nor lightweight semantic services approaches fulfil service tasks
automation, hence our motivation for a hybrid approach that provides handy
services annotation and complex reasoning.
Hybrid Semantic Web Services approach 5
Fig. 1. Conceptual comparison between WSMO and MSM
Acknowledgments. We kindly thank the NoTube project for generously fund-
ing this research and being a validation framework for the discussed ideas.
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