The metadata service allows external consumers to obtain information about the AOT objects within Microsoft Dynamics AX, such as tables, queries, forms, and so on. When we take a look at the operations available on the service, we can see the following two types of operations:
Operations that return a list of object names, such as the
GetQueryNamesoperation which returns a list of query names available in the system
Operations that return metadata of one particular object to the consumer, such as the
GetTableMetaDataoperation which takes a list of table names and returns all of the metadata information available for these tables
You can find detailed class diagrams on MSDN describing the metadata classes at http://msdn.microsoft.com/en-us/library/gg845212.