I'm working on a Esri Silverlight Web API app and wondering the best way to handle the import of local spatial vector data files. Sometimes these will be your standard shape file but often these will be in vendor specific proprietary file formats that will have to use special API's to parse out the data within them. My question is whether it would likely be a better practice to handle the data conversion on the server side vs. attempting to do it on the client side?
Doing that kind of thing server side would be a more scaleable option. Using your app to upload that data into ArcGIS Server DataInterop or Safe/FME which can them publish to a webservice for display on your app is the easiest to maintain.
As then you are removing the dependency of your App speaking all these differnet formats and it just is needed to push up and display the data; let the backend handle the data format or conversion.
You can even if you want a lowest cost option look at some of the OSGeo stuff; host that on a server, then write some webservices that you call from your SL app to push up to them; reshape the data to be overlayed in your front end.
Silverlight is really just a Rich-UI tool; you don't want to make it too burdensome on the client machine; much like a web-app its really geared to display rich information and not be a replacement for dedicated tools.