Sensor Networks’ Integration - Application and Multidisciplinary Aspects of Wireless Sensor Networks - page 109

The rendezvous component has the central role in the system. It provides a repository
for all resource descriptions currently available in the system as well as two inter-
faces: publishing and lookup. The publishing interface is used by resources to
register in the rendezvous and publish own description. The lookup interface is
used by resource clients to search for resources capable of fulfilling the clients'
requests. This type of architecture allows late binding of resources, i.e., the applica-
tions do not have to define which resources shall be used, but only the type of
information required by the application. Based on the description of the required
information, the Resource layer provides the actual resources that can most effi-
ciently at a given time provide the requested information.
All resources provide access policies as part of their descriptions, outlining who and
under which circumstances can access a given resource. The rendezvous component
uses these policies to grant or refuse access to the resources based on their credentials.
The proposed architecture remains to be tested and validated in a test bed com-
bining a number of different applications in a real-world setting. Based on this
evaluation the architecture shall be improved. A number of interesting points
remain to be resolved and proved like the scalability of the system, interaction
between different SENSEI system, management of such system and its compo-
nents, etc. The project is very well embedded in the EU's FIA initiative and to a
great extent influences the design of a Future Internet with the specific real-world
requirements.

5.4 Conclusions

In recent years many SNIFs have been proposed as a result of a tremendous
increase of heterogeneous WSNs deployments. This chapter describes the existing
SNIFs from a historical perspective and compares their functional and nonfunc-
tional properties. Also a description of currently developed systems is provided
with a perspective view on trends in mobile and future internet.
Currently there is no existing standard technology for the SNIFs and none of the
developed systems has gained prevailing attention as a reference model for future
research. However, some of the described frameworks are built by a large consor-
tium of industrial or academic partners (e.g., SENSEI) or are promoted by a stan-
dardized organization (e.g., Sensor Web Enablement). Others are developed and
available as an open source project used by an increasing number of contributors
and users (e.g., GSN). It will take some time until the SNIFs gain broad attention
as an integral part of the communication system. Before then, WSNs have to be
largely deployed and ubiquitous so that the benefits of SNIFs become pronounced
and they will emerge as the only solution to handle and manage the amount of data
produced by the sensors. This may happen soon because the WSNs market will
grow over eleven times within next 10 years [ 22 ]. Then the SNIF which is most
advanced and provides broad scope of features will have the biggest advantage and
potentially will dominate other solutions.