Web Services Composition and Geographic Information - Geographical Information Systems: Trends and Technologies - page 105

(DCOM), Java Remote Method Invocation (RMI) and Common Object
Request Broker Architecture (CORBA) which, although based on different
methodologies, had the common goal of simplifying the development of
distributed applications. However, although interesting, all these solutions
had and have, on the whole, several limitations, such as the tight coupling
between the various developed components and the presence of mature
development tools, just realized for a specifi c platform. Furthermore,
developing non-trivial applications by using these technologies is still
complex, because they lack a reference implementation, a standard
in the deployment of software solutions and a support for deploying
applications in environments with strict security needs (Henning 2006).
The above-mentioned diffi culties and the growing trend in the research and
development of loosely coupled solutions, meant to ensure both, a platform
independence and a greater sharing and reusing of functionalities, have
found in the Service Oriented Computing (SOC) paradigm and in the Service
Oriented Architecture (SOA) a new way for designing and implementing
distributed applications.
The general defi nition of service can be met by any software system,
however the most widely adopted description of Web service comes from
the World Wide Web Consortium (W3C) which represents the organization
in charge of 'leading the World Wide Web to its full potential by developing
protocols and guidelines that ensure the long-term growth of the Web'
(http://www.w3.org/). According to W3C a Web service 'is a software
system designed to support interoperable machine-to-machine interaction
over a network.' It is also relevant to guarantee the interoperability property
in environments handling large amounts of complex information, such
as geographic information. Indeed, improving the effectiveness and the
performances of any overall solution through the usage of distributed
geographic information services represents a primary goal for the
geographic community that has devoted many efforts to this achievement,
through the initiatives carried out by the Open Geospatial Consortium
(OGC) which represents the reference organization for 'the development
of international standards for geospatial interoperability' (http://www.
opengeospatial.org/). In particular, the opportunity to use the enormous
amount of geographic information accessible via OGC services within W3C
services is one of main reasons stimulating the recent efforts to seamlessly
combine these two different worlds. In fact, the geographic community has
recognized that a more complete integration among the underlying protocols
would allow for employing the well-established standards specifi ed for the
W3C platform. To this aim, OGC has set a special working group in order
to provide general recommendations and guidelines for making differences
between OGC and Web services transparent when the service composition is
applied to them. However, despite the simplicity behind the general idea of