Common Data-Related Problems
| Understanding and Deploying LDAP Directory Services > 8. Namespace Design > Examples of Namespaces |
Examples of NamespacesNow that we've described the purposes of a namespace and the major decisions that must be made when designing one, we turn our attention to some examples that should help illustrate the points we've been discussing. Here we consider both flat and hierarchical namespaces. (More design examples can be found in Part VI, "Case Studies." ) Flat Namespace ExamplesWe advised you to design your namespace to be as flat as possible within the constraints created by your replication, access control, and other needs. This section describes two examples of flat namespaces for the mythical Airius company. In the first example, a completely flat space is created. The naming attribute chosen is cn for simplicity. Each entry is named using a sequentially generated number that has no other significance. The resulting namespace is shown in Figure 8.13. Figure 8.13 An example of a flat namespace. Our second flat namespace example introduces a bit of hierarchy, with a flat namespace beneath each hierarchical component. The small amount of hierarchy in this namespace is used only to group different types of objects under a common portion of the tree. This has the effect of insulating namespace changes in one space from the others. It also makes it possible to partition and therefore replicate information on these same boundaries. Administrative control can also be distributed on these boundaries. The resulting namespace is shown in Figure 8.14. Figure 8.14 An example of a flat hierarchical namespace. In our experience, a namespace like the one shown in Figure 8.14 is nearly optimal in many environments. It has enough hierarchy not to hinder you when your needs change (for example, in replication or access control); however, the hierarchy it does have is not based on information likely to change (for example, geographical or organizational information). Hierarchical Namespace ExamplesThere are reasons you may need a hierarchical namespace, perhaps because of limitations in the directory software you've chosen or because of constraints imposed upon your directory by applications. This section illustrates two examples of hierarchical namespaces based on different hierarchical schemes. Again, we use the mythical Airius company as our guinea pig. For the first hierarchical example, consider that Airius is a global company distributed across three continents. Airius has an office in each continent that must have control over its own data, yet the sum total of the data must appear to the outside world as a single, coordinated information tree. Taking a lesson from the flat namespace example, Airius decides to use a similar namespace in each of its divisions. Because divisions need autonomy in their ability to manage, access, and change their own data, the top-level namespace hierarchy is divided using a geographical scheme. The resulting namespace is shown in Figure 8.15. Figure 8.15 An example of a hierarchical namespace. Our second example of a hierarchical namespace is based on Airius's internal organizational structure. Although you might be able to rationalize building such a namespace, we don't recommend it. But, in this example, the misguided Airius directory designer has decided to forge ahead. To reflect the organizational hierarchy, he's chosen to use the ou attribute with values corresponding to department names . To name leaf-level entries, the cn attribute has been chosen with a value of first name, middle initial, and last name. Name collisions are handled by appending a number to entries that collide. The resulting namespace is depicted in Figure 8.16. Figure 8.16 Another example of a hierarchical namespace.
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Index terms contained in this sectiondesignnamespace flat namespace examples 2nd 3rd hierarchical namespace examples 2nd 3rd directories namespaces flat namespace examples 2nd 3rd hierarchical namespace examples 2nd 3rd flat namespaces examples 2nd 3rd hierarchies namespaces examples 2nd 3rd |
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