Database Server Models for WMS and WFS Geographic Web Services - Geographical Information Systems: Trends and Technologies - page 169

Conclusion
To facilitate data and service interoperability, the Open Geospatial
Consortium (OGC) proposes web services such as Web Map Service (WMS)
and the Web Feature Service (WFS). These services allow a given system
to access data from distributed data servers as soon as they both respect
a common interface. These interfaces are based on operations such as for
example GetCapabilities, GetFeatureInfo, and GetFeature.
These services present some weaknesses for the GetFeatureInfo
operation of WMS and GetFeature operation of WFS from the semantical
point of view. The DataBase Administrator of a distributed service does not
know, by defi nition, the clients' needs (here end-users or applications using
these services). The clients do not know the database schema (respectively,
logical and external). Therefore, it is widely desirable to offer a mechanism
close to the notion of a dynamic view in order to provide a better relevance
to users' needs. This mechanism requires an enhancement of the database
conceptual model from the server side.
The proposed extension defi nes Relevant Links (RL) between two sets
of attributes belonging to the same class, between attributes and methods
(i.e., functions) of the same class and fi nally between two sets of attributes
belonging to two different classes (linked or not by constructors of the
conceptual data model). Methods are viewed as attributes. In fact, users
ignore the nature of available data (simple or computed). The goal is to
provide a data model associated with the result of a query designed upon
users' needs. The proposition must not modify the specifi cations of OGC
norms for web services.
Relevant links, associated with classes, give a semi-automatic
enhancement of the database schema provided with a result of a WMS
or WFS call for GetFeatureInfo or GetFeature operations. A classifi cation,
based on a lattice, automatically gives the better enhancement of the external
database schema provided with a result.
Perspectives of this work is to provide a metric evaluation of
performances with real size applications focusing on the database server
aspect without taking into account the network parameters (e.g., bandwidth)
that are uncontrollable and not relevant for this proposal.
References
ANSI-SPARC Architecture. http://en.wikipedia.org/wiki/ANSI-SPARC_Architecture.
Bedel, O., S. Ferré, O. Ridoux and E. Quesseveur. 2007. GEOLIS: a logical information system
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371-390.
Brodie, M.L. and J.W. Schmidt. 1982. Final report of the ANSI/X3/SPARC, DBS-SG relational
database task group, SIGMOD Record, Volume 12, Issue 4.