The DCE Namespace
The DCE namespace is the set of names used by the DCE Directory Service. It is hierarchical, similar to the structure of a UNIX file system. Names can be typed or untyped, reflecting the different name formats supported by the two global directory services, GDS and DNS. GDS names are typed, that is, they consist of a type and a value separated by an = (equal sign). A name such as /C=US/O=ABCcompany, names an object that exists in GDS. An untyped name consists only of values such as abc.com; DNS names use this format.
The following figure shows the root of the DCE namespace, indicated by the /... prefix, and four cell entries below it. The two cells on the left, /.../C=US/O=OSF/OU=DCE and /.../C=CA/O=B-College/OU=EE-Department, are in the X.500 namespace, while the two cells on the right, /.../company_b.com and /.../cs.univ.edu, are in the DNS namespace.
Four Cells in DCE Global Namespace
The following figure shows the top of a typical DCE cell namespace. It contains an entry for security information, an entry for the cell's DFS file system, an entry for subsystems such as DCE services, an RPC profile entry, and an entry for host names. (See the OSF DCE Administration Guide - Introduction for more information on the cell namespace.)
Top of a Typical DCE Cell Namespace
The following is a list of examples of typed and untyped names.
/.../C=US/O=OSF/OU=DCE/sec/principals/snowpaws
/.../C=US/O=OSF/OU=DCE/fs/usr/snowpaws
/.../cs.univ.edu/sec/principals/ziggy
/.../cs.univ.edu/fs/usr/ziggy
The /... prefix indicates that the name is a global name. The first two names are typed names using X.500 syntax, and the second two names are untyped names using DNS syntax. The first name in each set indicates the name of a user in an authentication database; the second name in each set is the user's home directory in a file system.
In each of the name examples, there is a global component and a local component. The global component consists of a cell name, which is registered in a global directory service. In one case, the cell is an entry in the X.500 namespace: /.../C=US/O=OSF/OU=DCE. In the other case, the cell is an entry in the DNS namespace: /.../cs.univ.edu. The remainder of the name is an entry in the cell's namespace; for example, /fs/usr/snowpaws.
The names listed above reside in the DCE cell namespace, but it is also possible to maintain names in the X.500 namespace by using GDS. An example of this kind of name is /.../C=US/O=OSF/OU=DCE/CN=SIG-DCE. This name could be used, for example, for an electronic mail list.