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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
5. Using ESRI software in Collaboration with
Other GIS's
In 2001, ESRI began to discuss g.net—a new architecture for
sharing and using geographic information system (GIS)
information from distributed sources. g.net is an architectural
vision for how ESRI users build parts of and participate in a
Spatial Data Infrastructure. g.net describes how ArcGIS,
ArcIMS, and other ESRI software technology are used.
ArcGIS, ArcIMS, ArcSDE, and other ESRI software can be
used to implement all of the functional nodes in a Spatial
Data Infrastructure. This architecture is known as g.net.
ArcGIS tools can be used for SDI in the following ways
(ESRI. March 2003):
. Client access - Any GIS user wishing to access information
and services remotely can connect to and use metadata
servers and GIS portals. ArcIMS includes a range of client
applications to connect to and use standards-based Metadata
Servers and GIS portals. ArcIMS clients can include the
Metadata Explorer, various HTML- and Java"M-based Web-
mapping clients, and other GIS desktops. These include
ArcReader™, ArcView®, ArcEditor™, ArcInfo™,
MapObjects® for Java, and ArcPad®.
. Create, manage, and serve metadata- With ArcGIS, users
can create and update FGDC- and ISO-compliant metadata.
Using the standards-based ArcIMS Metadata Server and
ArcSDE®), users can manage and serve metadata catalogs on
a local network, a secure network, or the World Wide Web.
The ArcIMS Metadata Server can be accessed through
standards-based ArcIMS services and through Open GIS
protocols, such as Z39.50.
. Create, manage, and serve GIS information- GIS users
build and manage their geographic data and information
using ArcGIS and ArcSDE. They can openly serve data,
metadata, online maps, and other information using ArcIMS.
ArcIMS services can be accessed with a wide range of clients
via GIS and XML-based Web services standards.
System Components
GIS Portal
Components
Spatial Management
Components
Data Management
Components ? SQL
System Environments
HTML, HTTP, XSL, XML, JSP
Java Beans, Servlets
[ TCP/IP, Sockets
Figure 4: ESRI GIS Portal Architecture (Gerco Hoogeweg.2004)
6. The role of standards for SDI and key content
and metadata specifications
Until the mid-'90s, organizations purchased geographic
information systems that closely tied applications to a native,
proprietary spatial data model. These early nonrelational file
Structures were highly optimized for fast access to data and,
being file based, were relatively easy to distribute between
sites using the same GIS vendor software. However, the
ability to share data among users within an organization was
limited by network protocols such as network file system
(NFS). Data sharing between organizations with different
GIS vendor systems was limited to data converters, transfer
standards, and later open file formats. Sharing spatial data
with other core business applications was rarely achieved.
Gradually, GIS models evolved into georelational structures
where related attribute data could be stored in a relational
database that was linked to the file-based spatial features.
However, the georelational format had limited scalability,
and the dual data structure (spatial features stored in
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proprietary file-based format with attributes stored in a
relational database) meant that the GIS could not take full
advantage of relational database features such as backup and
recovery, replication, and fail-over. In addition, supporting
large data layers required the use of complex tiling structures
to maintain performance, and sharing spatial information
with other core business applications was still not possible.
In the mid-'90s, new technology emerged that enabled spatial
data to be stored in relational databases (often referred to as
spatially enabling the database), opening a new era of broad
scalability and the support of large, nontiled, continuous data
layers. When
the new spatially enabled databases were combined with
client development environments that could be embedded
within core business applications, the sharing of spatial
features with core business applications, such as customer
management systems, became possible. In addition, these
spatially enabled databases allowed organizations to take the
first steps toward enterprise GIS and the elimination of