The NSI interface allows you to lookup objects using group and profile entries. You can also lookup attributes associated with an object.
Attributes can be binary or string.
You can also define new object classes and attributes. It is typically desirable to store only RPC related information in CDS that doesn't change very often. CDS should be used as a rather static replicated distributed namespace rather than as a dynamic distributed database. Storing the location of application servers and their static attributes is what CDS is best suited for. Junctions provide a single namespace.