The Metis Support Services interfaces are not visible to the application programmer. They are hidden within the VEM, controllers, and the user profile. At this time, three key interfaces have been identified. The DirectoryInterface has been designed and implemented. The CodeServiceInterface and the MetisSecurityInterface are being developed.
The directory client uses the DirectoryInterface to avoid being tied to a single directory protocol. Any physical directory service can transparently plug into Metis simply by enhancing the Metis Directory Server with updated implementations of the DirectoryInterface. The interface has been kept small, containing only one method, to minimize the complexity of directory access. When the VEM client is requested to access the Metis Directory Server (e.g., an AFE called the requestService() method), the VEM calls the lookUpService() method on the directory client. The authorization object, name, and attributes passed to the VEM are passed as arguments to the lookUpService() call.