The Extract Data and Email Task model that is in ArcGIS Server 10 needs to be modified a bit in order to use with silverlight. Currently the GPMultiValue:GPString data type is not in the API so the Layer to be clipped must be fixed in the model itself. Other parameters can be passed normally.
Here's what I did:
1. Create a graphics layer
2. Create a Draw object for drawing polygons add them to the graphics layer for display
3. Add all the polygons drawn by the user to the parameter of type GPFeatureRecordSetLayer
GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
Graphic graphic = new Graphic()
{
Geometry = args.Geometry,
Symbol = _activeSymbol
};
graphicsLayer.Graphics.Add(graphic);
parameters.Add(new GPFeatureRecordSetLayer("Area_of_Interest", args.Geometry));
4. Then add the rest of the parameter and finally submit the job