Working with the Web ADF Map control[转自EDN]

In the multi-source Web ADF, each Map control creates a MapFunctionality to work with a Value object MapDescription on the client.  The MapFunctionality uses this MapDescription to interact with the mapping capability of the ArcGIS Server map server object, such as drawing a new map image.  The MapFunctionality MapDescription stores Map control state, while the MapResourceLocal MapDescription stores resource state - which can be shared by any MapFunctionality that uses the resource.  By default, each MapFunctionality uses its own MapDescription to manage state.  In either case, the MapResourceLocal instance uses the MapServerDcomProxy class to create server context and manage stateless interaction with the map server object via the IRequestHandler interface.    MapResourceLocal also provides access to fine-grained ArcObjects on the server.  A reference to the MapServer object via a COM proxy is available via the MapServer property.  Server context is available via the ServerContextInfo class.