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172 Selected Studies on Software and Information Systems
6.1.3 Semantic Web Services
The Web is primarily designed for use by humans. Nevertheless, there is an effort to automate
its use and bring the Web more accessible for machines. This has brought forward the need for
machine processable representations of semantically rich information: a vision at the heart
of the Semantic web [17]. Nowadays, approaches based on giving additional information –
semantics, to the content of the Web are researched. The semantic description focuses both on
the content information and services available on the Web. In the case of Web services having
meta-data about their semantic, we talk about Semantic web services [22, 23, 29, 55, 66, 74].
Semantic web services are the result of the evolution of the syntactic definition of web
services and the Semantic web [23]. There exist approaches for the design and development
of applications employing Semantic web services [20]. In [76], a MusicBrainz project is
described, which aims to be the first using semantic web services. It’s a large database of
music meta-data which is accessible via a web service. Based on these meta-data it is easier
to search the music repository and find a relevant song. The meta-data are described using
RDF (Resource Description Framework).
Semantic web service can be considered as a result of the Web evolution (see Figure 6-4).
At the beginning, the Web was only a collection of documents, i.e. it offered static content.
This has evolved to an environment offering also different functionalities through services, i.e.
dynamic elements were appended. The popularity of the Web led to its enormous expansion
of documents and services available. This has been causing problems when searching for
a relevant information or service.
Dynamic
Web services
Semantic
web services
SEMANTIC WEB
Static
WWW
Semantic
web content
Syntax
Semantics
Figure 6-4. Web evolution to Semantic web services.
There is also change in the aspect of the Web user. Not only humans are considered as the
users of the Web. There are initiatives which aim is to bring the Web accessible for machines
– software agents. These can use methods which are more resistant to the problem of Web
expansion than humans are. The performance of the software agents is limited due that
the Web was initially intended for human interaction only. The main problems are weak
structuring and hard machine interpretation of the Web resources. The initiative which tries