Using the ArcGIS API for Microsoft Silverlight #feduc

If you are considering Microsoft Silverlight as an option to build a rich internet applications (RIA) while leveraging ArcGIS for geospatial web services, the ESRI team provided some guidelines during a presentation at the FedUC.

To get started, they advise developing the application with a combination of Visual Studio 2008 SP1 and Silverlight 3 although the current version of ArcGIS supports Silverlight 2 but will in the next release. As a platform for building the user interface (UI) and visualizing the application they also recommended Microsoft Expression Blend 3.

Why Expression Blend? While Visual Studio provides the platform for developing the "code behind" buttons, tools, etc., Expression Blend is more for the graphic designer.  But for those organizations that don’t have both a developer and a designer,  the two applications work in tandem. The actual "code behind" the UI is primarily extensible application markup language (XAML).

The ArcGIS API is built on Silverlight and Windows Presentation Foundation (WPF). The API allows the developer to combine RIA with ArcGIS Server and other services like Bing Map Enterprise Services. Once developed, applications are then rendered in a browser using the Silverlight plugin. The API is powered by ArcGIS Server REST services and is free for non-commercial users.

The features of the API include both tasks an controls. The tasks include "find data," Query," "Address Locator," and "Routing." Silverlight controls already include data grids and charts while the ESRI toolkit includes map-related functions such as "navigation," "map tips," "toolbar," "FeatureDataGrid," and a "MapProgressBar." The API also includes starter templates as well as extensible triggers, actions, and behaviors.

Each Silverlight application is compiled as a DLL just like a traditional .NET library and published the app as a XAP file,  which is a ZIP archive containing Silverlight applications.  To use XAP file the web server must serve out the XAP file with the correct MIME type. There is a need for cross domain access as well and this access requires a clientaccesspolicy.xml file; if not you’ll get an error because client policy is in place. See http:/services.arcgisonline.com/clientaccesspolicy.xml

More information on the ArcGIS API can be found at
Resources.esri.com. Go to the resource center for SDKs to download API - you’ll need an ESRI global account.