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MDEP Deploys Distributed GIS Application
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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 button
  • 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 the application

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
Stuart Rich
St. George Consulting Group, Inc.
16 School Street
Rockland, Maine 04841
Tel.: 207-594-3048
E-mail: sturich@stgeorgeconsulting.com

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.

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