Geographical Information Systems (GIS) presents data-intensive environment for
acquiring, processing and sharing geo-data among interested parties. In order to serve
geographical information to users in such environment, Service Oriented Architecture
(SOA) principles have gained great importance. In SOA-based systems, Information
Services support the discovery and handling of these geospatial services.
Some options for Information Services in SOA-based GIS systems include a) the Open
GIS Consortium (OGC) Web Registry Service (WRS) and b) the Universal Description,
Discovery, and Integration (UDDI). WRS is an OGC standard to discover/publish service
information of geospatial services. It presents a domain-specific registry capability for
geospatial information. UDDI is domain-independent standardized method for
publishing/discovering information about Web Services. As it is WS-Interoperability
(WS-I) compatible, UDDI has the advantage being interoperable with most existing
Grid/Web Service standards.
This study presents an approach combining domain-specific registry capabilities of WRS
and WS-I compatible UDDI Specifications. We extend UDDI Information Model to
support geospatial services. Our approach supports not only quasi-static, stateless
metadata, but also more extensive metadata requirements of rich interacting systems. The
implementation of our approach is being used to support a GIS workflow system which is
a part of NASA Solid Earth Virtual Observatory (SERVO) Grid project.
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The Open Geospatial Consortium (OGC) defines a number of standards, both for data models
and for online services, that has been widely adopted in the Geographical Information System
(GIS) community. This has lead to a number of software development efforts, online data
archives, and application communities. We survey these in the first part of this report. We
furthermore find that the OGC standards are very compatible with Web Services standards,
although they are not technically implemented this way. We therefore, in the second part of
this report, describe our group’s efforts to reimplement OGC standard services as web
services. We focus particularly on the Web Map Service.
We also have built bridging services that allow our Web Service compatible WMS to interact
with non-Web Service versions of WMS. Cascading WMS is the key point in our proposed
solution for the interoperability problems in the GIS WMS services. Since Web Service
oriented WMS has different request response paradigm from non-Web Service versions, we
have extended cascading WMS by adding request handler functionality. This kind of WMS
behaves like both a cascading WMS and a proxy to handle different types of requests to
overcome interoperability problems between different WMS systems.
We describe our continuing work on implementing Open GIS Consortium (OGC) compatible Grid
Services for the International Solid Earth Research Virtual Observatory. Our initial efforts focused
on collecting Earthquake and GPS data from various sources, converting them to GML and
enabling query capabilities using pure Web Services approach. We have extended this work by
creating Web Services implementations of OGC-Web Feature Service and OGC-Web Map Service
for serving GML-formatted data. We also describe a Fault Tolerant High Performance Information
System (FTHPIS) to tie these services together.
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