The San Diego Bay Watersheds Common Grounds Project was created to incorporate data from water quality monitoring programs and integrate this data on a watershed level using a web-based interactive application to serve as a broad communication, education and decision-making tool; and to further develop the region's capacity to understand and assess processes affecting our water resources.

Common Ground System Architecture for Internet Mapping Applications

The Common Ground website hosts a server-side internet mapping application where client-side database and program components are separated from server-side components. All computations are performed on the server side and results are sent back to the client browser. This is a three-tiered system architecture, with presentation located on the client side, logic resides on a server, and data is stored on a separate data server. Three-tier architecture was chosen over a traditional two-tier configuration that allocates presentation to the client, stores data on the server, and splits logic between the client and the server. The additional data server frees up the general server for more extensive and vigorous processing making the three-tier system architecture a flexible and customizable framework for Common Ground's Internet Mapping Services.


The Common Ground project will require two servers for creating a comprehensive Internet mapping services. One server will be used for the Web Server, and simultaneously as the Internet Map Server. A second server will access the GIS database and metadata from the Metadata Server.

Web Mapping Server
CPU: Dual Xeon 2.4 GHz
Memory: 1GBHard disk size: 100GB
Network connectivity: 100MB Fast Ethernet
Metadata/GIS Database Server
CPU: Dual Xeon 2.8GHz
Memory: 4GB
Hard disk size: 260GB
Network connectivity: Gigabit Ethernet


ESRI ArcIMS 9 was selected as the cornerstone for this project. For data sharing between other systems and software, ArcIMS supports Open GIS Consortium (OGC) Web Mapping Service (WMS) standards, an industry initiative to promote compatibility between different map types and data.

Common Ground's Home Page

Operating System: Windows 2003 Server - capable of ASP (Active Server Pages) functions and document indexing functions needed to support multi-user access.

Web Servers: Software supporting server hardware operations are Microsoft Internet Information Server (IIS) and Apache (freeware).

Internet Mapping: ESRI ArcIMS 9 provides both vector and raster display and accepts a variety of geospatial data formats. This is supported on the user end with ESRI Desktop GIS software.

GIS databases: ESRI ArcSDE 9.0 with MS SQL server 2000 provides advanced spatial query capabilities, as well as links to the ArcIMS metadata server.

Metadata: ESRI ArcIMS 9.0 Metadata server extension provides metadata query, GIS portal, and map search functions via ArcSDE. Metadata will be generated by eXtensible Markup Language (XML) and ESRI ArcCatalog. Java Server Page (JSP) and Tomcat facilitate metadata search and indexing functions.

User Interface: ArcIMS Java Viewer and ArcIMS HTML Viewer will be the user interface for the system on basic and advanced levels. Java scripts will be utilized to customize the Graphic User Interface (GUI).

Customization: Java applets will support special applications as needed.

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