MDEP Deploys Distributed GIS Application
HOSS was developed using Borland Delphi 6, ArcObjects
8.1 (ArcEditor license), and Oracle 8.1.7 with advanced replication.
With this architecture, SGCI can deliver an application that seamlessly
integrates relational business data with spatial data in fully replicated
databases. For office-based users of HOSS, access to the application
is provided through the MDEP production Citrix server.
The core platform employs ArcObjects 8.1 and ArcSDE.
Because ArcObjects is fully COM-compliant, SGCI has been able to
utilize a best-of-class Windows development tool (Borland Delphi
6) and a best-of-class DBMS (Oracle) to create a fully integrated
database and GIS application in a distributed environment. ArcObjects
also supports complete printing functionality so that full-featured
maps can be printed from within the application.
One of the greatest challenges in developing this
system was managing the replication environment. Because ArcSDE
does not support multi-master replication for enterprise geodatabases
yet, SGCI had to be very creative in implementing functionality
that directly captured GPS spill locations and entered them into
the enterprise geodatabase. [Multi-master replication is a model
that allows entries to be written and updated on any of several
replica copies without communication with other masters before the
write or update is performed.]
Alternative deployment architectures, such as utilizing
MDEP's Citrix platform through some sort of wireless connection,
were considered. However, the Statewide nature of the responders'
jurisdictions and the inadequate coverage of wireless services and
cellular connections precluded this approach. SGCI also looked at
personal geodatabases instead of distributed deployments of ArcSDE
but found that the Microsoft Jet Engine, used by the personal database,
could not handle the volume of spatial data implicit in Statewide
environmental and transportation data.
With HOSS, responders now have seamless, integrated
access to spatial and relational data that provides the same level
of capability for responders both in the field and the office. For
these users, the application supplies
- Distributed access to all relevant MDEP business databases
and enterprise geodatabase layers with the click of a single
- Seamless integration between MDEP business and spatial data
- The ability to capture and store GPS location data directly
in the enterprise geodatabase with the click of a single button
- Automatic creation of feature-level metadata for each spill
- Printing of full-featured maps of spill locations from within
By retrieving and utilizing GIS data more quickly
and accurately, responders can more rapidly process spill remediation
paperwork. HOSS also provides extensive historical data on other
spills and helps responders pinpoint the public health and environmental
risks that might otherwise be ignored or underestimated.
For more information, contact
St. George Consulting Group, Inc.
16 School Street
Rockland, Maine 04841
About the Author
Stuart Rich, president of the St. George Consulting
Group, Inc. (SGCG), has been developing enterprise database solutions
for the past 10 years for local construction companies, research institutions,
state government, large corporations, and the United States military.
He has expertise in object-relational database design, spatial and
nonspatial application development, and the integration of spatial
and relational data.
Based in Rockland, Maine, SGCG is a software development
firm and Esri business partner that has on staff some of the leading
GIS developers in the country. SGCG applications have won awards at
the Esri International User Conference. Owing to its involvement in
the Esri beta program for the past three years, SGCG has a great deal
of experience with ArcInfo 8 object models and techniques for extending
those object models for enterprise applications.