Using named layers in a map provides users with some level of interaction with the map. The named layers are listed in sequence in the request, which determines the draw order of the map image. This is a good option if you want your application logic or users to select and deselect layers to control the display of information on the map.
Named layers are a very powerful capability for managing data. The purpose of a named layer is to indicate how the data in the table is styled. You can create reusable style definitions for a data set by building the complexity you want, such as themes, styles, and zoom level. To use it, you only need to call the layer by name.
This option provides similiar functionality to WMS. Rendering a map with named layers allows you to point directly to the named layer, whereas with WMS, the named layer must be first set up in a configuration file. WMS includes GetFeatureInfo whereas the Mapping Service does not.
For a SOAP example, go to the Spectrum Spatial SOAP Mapping Service Demo Page at
http://<server>:<port>/Spatial/MappingService/DemoPage.html and choose
Render Map1 example from the drop-down list.
For a REST example, see Center and Zoom with Multiple Layers.