If you create features like circles, ellipses or polygons and lines including circular arcs an publish those in an ArcGIS for Server map service they get translated into many small straight line segments. A simple cirlce exists after publishing for example of 50 instead of 2 vertices (depending on the radius). Therefore webgis plattforms can't provide feature edit functions for true arcs, circles an ellipses allthough filegeodatabases and sde are supporting such.
