![](bg7.png)
SWE framework.
The multilayer structure and the service approach
enable decoupling of components; in particular, each
Institution hosting and maintaining a sensor station
is allowed to store observations and deliver them to
multiple independent clients, in a standard,
interoperable way, well recognized and accepted at
European and global scale.
The success and reliability of the solution is
proved by the number of SOS services, which is
increased in the last few years (Tamayo et al. 2011).
Using advanced search in Google engine (e.g.
inurl:service=SOS inurl:request=GetCapabilities)
913 different SOS services are found, 456 of them
referred to the aquatic environment. They and their
observations are all potentially interoperable with
the observations distributed by our proof-of-concept.
If we consider the challenges defined in the
introduction, the proof-of-concept proposed is able
to cope with technological heterogeneity of the sites
and sensors since it is based on the use of OGC
standards, able to describe sites and sensors
characteristics but offering a uniform ways to
communicate among the implementation
components.
Quality check and harmonization are fostered by
the multi-layered approach that allows to include
components and tools aimed at those purposes at
different level; by example a fast-track quality
control can be performed before the storage of
observations in the repositories, while a spatially-
extended cross validation process can be included in
the Application layer, where values from multiple
sites are available.
Uniform metadata and a shared
sensor/observation model are also a way to describe,
search and compare quality.
But they are even more useful in facing the need
to provide descriptions of sensors and their status,
information necessary e.g. to maintain the network
and to compare the sensors’ performance.
Authors do not hide that the job to be done is
great: in particular the technological development of
the tools to implement SWE components (and in
particular SOS) is still overwhelming for the
community of marine researchers; the success of the
approach is linked to the development and
availability of easy to define, ready to use tools,
enabling site managers to friendly create their own
repositories and services. Cloud providers can also
offer a solution to the security issues linked to
service distribution in small institutions.
Another development is related to the syntactic
and semantic harmonization, which requires
intelligent applications that integrate the current
technological solutions and standards with
knowledge coming from the domain experts.
ACKNOWLEDGEMENTS
The activities described in this paper have been
partially funded by the LIFE+ Project EnvEurope
(http://www.enveurope.eu) and the Italian flagship
Project RITMARE (http://www.ritmare.it).
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