Performance

Previous versions of the GAINS mapping system had unacceptable performance profiles - it would take 5 seconds or more to render a map. The bottle neck was handling the mix of spatial and tabular queries - the GIS environment could do the fast spatial queries (which points are in the current visible extent) and the tabular environment could handle the attribute queries ("show me only H5N1 Positive cases"), but linking the two was problematic.

Since the system was only dealing with point data, the team opted to skip the spatial query, and do everything in the database using simple Latitude and Longitude fields embedded within the epidemiological datasets. This facilitated the bounding box queries to be combined with the complex attribute queries, and still have query times in the 100's of milliseconds.

Focused Tools

Creating a very focused application helps ensure that the system is easy to use. By not trying to be all things to all users" the development effort was put into a small set of tools which are both easy to use, and very fast.

High-Performance

Since the release of Google Maps, end user expectations for web-based mapping application are very high. And in a high-energy environment like an emergency response operations center, time is of the essence. This system utilizes map caches for the majority of the data sets, thus making most map interactions nearly instantaneous. Analytical operations utilize the ArcGIS Server SOAP API which is also extremely responsive.

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Design Phase

The design phase of this project focused on the creation of mock-ups for the system. These gave the WCS team a better feel for how the system would look, as well as how the workflows would be implemented.

Agile Development

Through the development process, the team released the software to the client every two weeks. This transparency during development ensured that both the team and our clients knew exactly what was being built, and that it was meeting the actual needs of the users.

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DotNetNuke (DNN)

DNN is an open source content managment system built on Microsoft ASP.NET. The Wildlife Conservation Society runs a number of web sites based on DNN, and the modular nature of the system allows them to plug-and-play components across their whole ecosystem of sites.

Microsoft Virtual Earth

Since the GAINS dataset is global in nature, WCS needed a map canvas with a high-quality global dataset. The Virtual Earth control easily facilitated fetching and rendering points from a custom web service. By using Ajax techniques, the team was able to minimize the amount of data transmitted to the browser, thus increasing the performance of the system.

ArcGIS Server

Although the point data comes directly from the SQL Server database, ArcGIS Server is used to fetch the species flyway polygons from an layer in ArcSDE. A custom webservice was created which uses the ArcGIS Server SOAP API to get the feature geometry from ArcSDE, and then transform it into GeoJSON, which is then used within Virtual Earth to create the flyway polygon.

Dojo Toolkit

The Dojo Toolkit is a comprehensive javascript application framework that can be used to build rich client application in the browser. It is used for the menu's and the dialog boxes on the GAINS application.