In order for a Command to perform an action on the server for a PageLayout, a class must be created that implements this interface. The Command then sets its ServerActionClass to this class, typically at design time in the toolbar items editor.

The class implements the ServerAction method. This method handles the server-side action. This method receives one argument, a ToolbarItemInfo object. This object contains information about the item, toolbar and buddy controls of the toolbar. The buddy controls collection may be used to obtain a reference to the PageLayout, as discussed at ToolbarItemInfo.BuddyControls.

The following sample implements IMapServerCommandAction, which is similar to IPageServerCommandAction: the Common_AddCustomTool sample in the SDK Web Applications samples (also available at ArcGIS Resource Center:http).

Reference