Data and metadata on the Web is usually exposed via a wide range of Web APIs and Web services, such as the YouTube APIs to name a well known example. Such Web interfaces usually are very heterogeneous, in that they use different transport/protocol mechanism (SOAP, REST) and very diverse input and output message schemas (XML, JSON, RDF). To aid developers and applications in tracking, discovering and orchestrating suitable services across the Web, semantic services integration exploits semantic technologies to add a layer of structured and accessible service annotations. These can be harvested and processed by humans as well as machines.
Why is this of interest to NoTube?
NoTube is fundamentally based on a service-oriented approach. Therefore, the challenges tackled by semantic services integration are of interest to the project in several ways:
1) Helping developers to track TV/NoTube related Web services
Structured service metadata allows NoTube developers and third parties to document, annotate and – of course – query the range of NoTube services. That way, for instance, services can be found which tackle certain problems (e.g. EPG recommendation or metadata transformation) and which satisfy certain criteria, e.g. being stable or responding with specific formats.
2) Providing NoTube applications with a single entry point to discover and orchestrate services
While service semantics are useful to provide smart search mechanisms to humans, they also enable NoTube applications to automatically discovery and orchestrate services for a given goal. Hence, instead of asking any smart TV or NoTube Web application to find and execute services which are spread around the entire Web, requests of all sorts can be directed to a “Semantic Web Services broker” which discovers and orchestrates services based on their semantic descriptions. That minimises the service integration effort for application developers and allows them not to deal with the actual service heterogeneities, such as the different input/output message structures or invocation protocols (REST vs SOAP).
What NoTube has done so far in this area
Much work has been done on semantically integrating services into NoTube at different levels. Thus, environments were provided which provide semantics and infrastructure for (i) rather light-weight services tracking and documentation as well as for (ii) reasoning-based automation of services tasks.
SmartLink – annotation and search for Linked Services:
SmartLink is short for “SeMantic Annotation enviRonmenT for Linked Services”. Simply put, it is an easy-to-use Web application aiding users in the creation of Linked Services – semantic service annotations following Linked Data principles. Amongst other things, it provides an interface to populate and query the Linked Services repository iServe with simple service annotations in RDF. In that, SmartLink/iServe will provide the first Linked Data store about (NoTube) services.
Semantic Web Services broker:
In addition to the more light-weight Linked Services approach, we have provided a more comprehensive and automation-oriented service broker. This environment is based on the reasoner and service execution environment IRS-III, the Web Services Modelling Ontology (WSMO) and the knowledge modelling language OCML. In addition, a number of NoTube applications, such as SugarTube, already make use of this technology. Below you can find a demo video which illustrates the use of the Semantic Web Services broker within SugarTube:
Future plans in NoTube
NoTube continues to investigate:
- Particular service integration requirements specific to the TV domain
- Light-weight Linked Data-based service annotation mechanisms
- Extending the state of the art in semantic service integration
Interested in collaborating with NoTube? Drop us a line and sign-up to our public mailing list (firstname.lastname@example.org).