Database Reference
In-Depth Information
One major driver in the area of geoprocessing and geospatial data man-
agement technologies is the OGC Interoperability Institute,
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where the OGC
is also developing and promoting diverse types of geospatial Web services.
Such type of Web services play an increasing role in geospatial data integra-
tion frameworks. Services do not just provide easy access to diverse types of
geospatial data using standard protocols and interfaces, but they also often
offer functionality that helps in resolving data conflicts. For example, request-
ing data in a particular projection or at a particular scale are important data
preprocessing steps that already can be accomplished by services rather than
at the data integration site. In this sense, such services provide some appli-
cation functionality too. There are a few geospatial Web services approaches
that address both interoperability and integration aspects, for example, based
on mediation,
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services,
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or a combination of service and mediation-based
techniques.
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In the following, we describe how integration infrastructures
can be built based on such services and architectures.
10.3.2 Service-Oriented Architectures
In the past few years, there have been significant developments in terms of
architectures and standards that help developers build Web-based services
that allow for a uniform and transparent access to data managed at different
sources. One such development is the service-oriented architecture (SOA),
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which allows an effective cooperation among data sources and data processing
components hosted at different organizational units. In particular, SOA sup-
ports reusability and interoperability of software and service components on
the Web, thus increasing the eciency of developing and composing new ser-
vices. In an SOA-based system, all data and process components are modeled
as Web services.
10.3.3 Registry and Catalog Services
Of particular interest in this chapter are catalog and registry services. As
scientific data are accumulating at an ever-increasing speed, it is very di-
cult if not impossible for users to know exactly the details of all the data
that might be relevant to their project. As such, repositories that provide
catalog services and allow users to interactively or programmatically search
and retrieve metadata that are related to the use of the datasets are playing
an inreasingly important role in scientific data management. In the context of
geospatial applications, OGC's Catalog Service for the Web (CSW) Implemen-
tation Standard
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provides this functionality in the form of several operations:
the mandatory GetCapabilities operation returns metadata about the specific
repository server (ServiceIdentification), the operations supported by the ser-
vice including the URL(s) for operation requests (OperationMetadata), the
