Deciding Between Referrals And Chaining - Netscape DIRECTORY SERVER 6.02 - DEPLOYMENT Deployment Manual

• Dynamic management.
You can add or remove a part of the directory from the system while the entire
system remains available to client applications. The database link can
temporarily return referrals to the application until entries have been
redistributed across the directory. You can also implement this functionality
through the suffix itself, which can return a referral rather than forwarding a
client application on to the database.
• Access control.
The database link impersonates the client application, providing the
appropriate authorization identity to the remote server. You can disable user
impersonation on the remote servers when access control evaluation is not
required. For more information on configuring database links, refer to the
Netscape Directory Server Administrator's Guide.

Deciding Between Referrals and Chaining

Both methods of linking your directory partitions have advantages and
disadvantages. The method, or combination of methods, you choose depends upon
the specific needs of your directory.
The major difference between the two knowledge references is the location of the
intelligence that knows how to locate the distributed information. In a chained
system, the intelligence is implemented in the servers. In a system that uses
referrals, the intelligence is implemented in the client application.
While chaining reduces client complexity, it does so at the cost of increased server
complexity. Chained servers must work with remote servers and send the results
to directory clients.
With referrals, the client must handle locating the referral and collating search
results. However, referrals offer more flexibility for the writers of client
applications and allow developers to provide better feedback to users about the
progress of a distributed directory operation.
The following sections describe some of the more specific differences between
referrals and chaining in greater detail.
About Knowledge References
Chapter 5 Designing the Directory Topology 89