Hierarchical Cell Names
In a hierarchy of cells, the names of one or more cells, called child cells, are registered in a cell's CDS; this cell is called the parent cell. The cell at the top of the hierarchy must be registered in a global directory service (GDS or DNS), but the cells underneath do not need to be, since they use CDS to communicate. A child has one and only one parent at any given time, while a parent can have more than one child.
The GDA is the communications gateway between the CDS namespaces of cells in a hierarchy, as it is between CDS and the global directory services. When the GDA receives a request for information about a cell, and the cell is a child cell, the GDA returns information about the CDS in the parent cell. The CDS of the parent cell provides the pointers to the child cell.
A child cell's name begins with the parent's global cell name, that is, the name of the cell beginning at the global root /.... (This name is also known as the parent cell's fully-qualified name.) It ends with the specific child cell name. The parent's global name can contain CDS syntax as well as GDS or DNS syntax, depending on where the parent cell is located in the hierarchy.
The following example shows the global cell names of two child cells.
Global Cell Name for Sales1
------------------------^---------------------------
/
Parent Global Cell Name Child Cell
--------------^-------------------------- --^--
/ / |
/.../C=US/O=XYZ/OU=Portland/subsys/PriceMax/Sales1
Global Cell Name for Marketing
_______________________^____________________________
/
Parent Global Cell Name Child Cell
--------------^-------------------------- ---^--
/ / |
/.../C=US/O=XYZ/OU=Portland/subsys/PriceMax/Marketing
The global cell name for each child includes:
· The parent's global name, /.../C=US/O=XYZ/OU=Portland/subsys/PriceMax.
· The child's unique CDS name, /Sales1 or /Marketing.
If a DCE administrator is establishing a hierarchy of cells during initial cell configuration, he or she must obtain a unique GDS or DNS cell name for the cell at the top of the hierarchy from the GDS or DNS global directory service authorities. All the cells beneath this cell share this name. The OSF DCE Administration Guide - Introduction provides details on how to obtain GDS and DNS cell names.
If a DCE administrator establishes a hierarchy of cells after the cells have been configured, the global names of the child cells change to point to the parent's cell name. Restructuring a Namespace provides details on how to establish a hierarchy of cells.