HP UX Direry Server manual Examples of a flat and an organizationally-based DIT

Figure 4-10 Examples of a flat and an organizationally-based DIT

Using a hierarchical DIT, a deployment must then determine the subject domain of the hierarchy. Only one choice can be made; the natural tendency is to choose the organizational hierarchy.

This view of the organization serves well in many cases, but having only a single view can be very limiting for directory navigation and management. For example, an organizational hierarchy is fine for looking for entries that belong to people in the Accounts department. However, this view is much less useful for finding entries that belong to people in a geographical location, such as Mountain View, California. The second query is as valid as the first, yet it requires knowledge of the attributes contained in the entries and additional search tools. For such a case, navigation via the DIT is not an option.

Similarly, management of the directory is much easier when the DIT matches the requirements of the management function. The organization of the DIT may also be affected by other factors, such as replication and migration considerations, that cause the DIT to have functional utility for those applications but very little practical utility in other cases.

From the above discussion, it is clear that hierarchies are a useful mechanism for navigation and management. To avoid the burden of making changes to an existing DIT, however, a deployment may elect to forgo a hierarchy altogether in favor of a flat DIT.

It would be advantageous for deployments if the directory provided a way to create an arbitrary number of hierarchies that get mapped to entries without having to move the target entries in question. The virtual DIT views feature of Directory Server resolves the quandary of deciding the type of DIT to use for the directory deployment.

Virtual DIT views provide a way to hierarchically navigate entries without the requirement that those entries physically exist in any particular place. The virtual DIT view uses information about the entries to place them in the view hierarchy. To client applications, virtual DIT views appear as ordinary container hierarchies. In a sense, virtual DIT views superimpose a DIT hierarchy over a set of entries, irrespective of whether those entries are in a flat namespace or in another hierarchy of their own.

Create a virtual DIT view hierarchy in the same way as a normal DIT hierarchy. Create the same entries (for example, organizational unit entries) but with an additional object class (nsview) and a filter attribute (nsviewfilter) that describes the view. After adding the additional attribute, the entries that match the view filter instantly populate the view. The target entries only appear to exist in the view; their true location never changes. Virtual DIT views behave like normal DITs in that a subtree or a one-level search can be performed with the expected results being returned.

For information about adding and modifying entries, refer to "Creating Directory Entries" in the HP-UX Directory Server administrator guide

4.4 Virtual directory information tree views 51