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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