Provide a default CMS_MODULE.is_installed: BOOLEAN implementation based on storage of custom value.

Now use CMS_MODULE.is_initialized: BOOLEAN as precondition of many routines.
Instantiation of node storage is now done in NODE_MODULE and not any more in CMS_NODE_API.
CMS_NODE_API can be instantiated only by NODE_MODULE.

src/service/cms_module.e

@@ -32,42 +32,57 @@ feature {CMS_API} -- Module Initialization
 			-- Initialize Current module with `api'.
 		require
 			is_enabled: is_enabled
+			is_not_initialized: not is_initialized
 		do
 				-- Redefine to process specific module initialization.
+			is_initialized := True
+		ensure
+			is_initialized: is_initialized
 		end
 
+feature -- Status		
+
+	is_initialized: BOOLEAN
+			-- Is Current module initialized?
+
 feature {CMS_API} -- Access: API
 
 	module_api: detachable CMS_MODULE_API
 			-- Eventual module api.
+		require
+			is_initialized: is_initialized
+		do
+				-- No API by default.
+		end
 
 feature {CMS_API} -- Module management
 
 	is_installed (api: CMS_API): BOOLEAN
 			-- Is Current module installed?
 		do
-			Result := is_enabled
-				-- FIXME: implement proper installation status.
+			Result := attached api.storage.custom_value ("is_initialized", "module-" + name) as v and then v.is_case_insensitive_equal_general ("yes")
 		end
 
 	install (api: CMS_API)
 		require
 			is_not_installed: not is_installed (api)
 		do
-				-- Not Yet Supported
+			api.storage.set_custom_value ("is_initialized", "module-" + name, "yes")
 		end
 
 	uninstall (api: CMS_API)
 		require
 			is_installed: is_installed (api)
 		do
-				-- Not Yet Supported
+			api.storage.set_custom_value ("is_initialized", "module-" + name, "no")
 		end
 
 feature -- Router
 
 	setup_router (a_router: WSF_ROUTER; a_api: CMS_API)
 			-- Setup url dispatching for Current module.
+		require
+			is_initialized: is_initialized
 		deferred
 		end