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Semantic Web Services 173
to bring solution to this problem is a Semantic web. Its aim is to ad additional semantic
meta-data to the resources available on the Web, i.e. it moves from pure syntactic level to
richer semantics level. This means that the Web resources are bound to meta-data describing
the meaning of the data. Hence, we are moving to the Semantic web including Semantic web
content and Semantic web services.
6.1.4 Developing Semantic Web Portals: without SOA versus SOA Based
The Web is a place where different information and services are available. There are several
cases when these are focused on a certain community of people with close interests. For these
groups different Web portals are suitable providing an entry point for accessing information
and services.
The Semantic web technologies offer means to support searching, organizing, processing,
and presenting information. These can be applied in the context of Web portals resulting in
Semantic web portals [48]. Semantic web portals are web portals collecting information and
functionalities for a community and are based on Semantic web technologies.
Semantic web portals can be built using different software development approaches. In
the next, we discuss the differences between building Semantic web portals without SOA
and based on SOA. We use a job offer portal (JOP) developed in the context of research project
NAZOU 1 [61] as an example to show the differences. First we describe the way this portal
was developed. Then we concentrate on how SOA can change this.
JOP offers its users several ways of navigation through the information space of job
offers using different presentation tools working with the ontological database produced by
a chain of data harvesting tools acquiring and processing data from the Internet. The main
requirements to JOP were:
– Adaptivity and adaptability of the system’s presentation and functionality.
– Built-in automatic user modeling based on user action logging with semantics and
automatic user characteristic estimation.
– Reusability and generic design suitable for multiple application domains.
– Extensibility with additional tools for specific tasks and overall flexibility with respect
to tool orchestration.
– Tolerance towards changes in the domain and user ontologies.
JOP [7, 8] was developed using an MVC based framework built on the pipes and filters
architectural pattern – Cocoon 2 . We have used the available portal block provided by Cocoon
to build JOP. It offered us a basic infrastructure which was configured and into which our
modules were put into. Figure 6-5 depicts an overview of the portal architecture that extends
the basic functionality of Cocoon with additional software components in order to fulfill the
aforementioned requirements.
1 Project NAZOU, http://nazou.fiit.stuba.sk/
2 http://cocoon.apache.org/