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The spread of the internet made actual the access to spatial data repositories via Web browsers
which can support the presentation of 3D objects using VRML (Virtual Reality Modeling Language)
- a network transparent protocol for communicating 3D graphics over the World Wide Web.
To achieve this every GeoToolKit class has got an mandatory member function producing output
in the VRML format.
To provide the access to spatial object repositories via Web-browsers we used
Common Gate Interface (CGI). A CGI script activated from a HTML-form connects (using the socket-stream
mechanism embedded in GeoToolKit) a permanently running GeoServer, whose task is to supervise all
GeoToolKit-compliant databases managed by the given ObjectStore server. To avoid permanent re-initialization
of the examined database GeoWeb (GeoServer's component responsible for the Web) performs sessions control
and provides for multiple asynchronous clients a safe concurrent access to data repositories.
Query results are returned back to the CGI-script either in the HTML-format for text data or in the VRML-format
when a graphical representation is required. If necessary GeoWeb generates new forms for a more precise pre-selection
of objects using either GeoToolKit's querying facilities or cascaded forms.
Basic geological entities turned out to be good mapped onto VRML representation (we use CosmoPlayer by SGI which is
free and supports VRML2).Currently the querying of data repositories is performed in a rather traditional mode via HTML-forms.
In order to provide spatial navigation capabilities similar to those implemented in the GeoStore browser we develop an
extensible set of graphical 2D/3D interface components using Java and a CORBA
compliant communication infrastructure.
For more information, see the following resources:
- GeoToolKit,
a C++ class library offering management of persistent spatial data.
- XDA,
the eXtensible Database Adapter - a framework for providing object
persistence in object-oriented programming languages by integrating the
powerful database facilities with the heterogeneous CORBA environment.
- GeoStore,
an information system for managing geological data.
- ObjectStore,
a real-time object database management system.
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