Chapter 9. Namespace Design

• The Structure of a Namespace

• The Purposes of a Namespace

• Analyzing Your Namespace Needs

• Examples of Namespaces

• Namespace Design Checklist

• Further Reading

• Looking Ahead

Designing a directory namespace is one of the most important tasks you will undertake when designing your directory service. The directory namespace provides the basic means by which you reference information in your directory, but it has many other implications as well. A properly designed namespace can lead to

• Easier data maintenance

• More flexibility in setting access control and replication policies

• The ability to satisfy a wider variety of directory-enabled applications

• More natural navigation through the directory

• Happy directory users and administrators

On the other hand, a poorly designed namespace can lead to administrative hassles when directory entry names change, replication or access control requirements change, or users try to find information. In the worst case, the namespace must be redesigned to support a vital new directory application. Poor design generally results in unhappy directory users and frustrated, overworked administrators.

The namespace you design for your directory has far-reaching implications that are often not at all obvious when you set out. The design of your namespace can affect replication, whether and how you are able to partition your data among servers or distribute administration of the directory, and other aspects of the service. Furthermore, changing your namespace after you've designed and deployed your directory service is a difficult task, unpleasant for administrators and often inconvenient for users.

These implications make namespace design one of the most critical tasks you will face during your directory design process. Don't be surprised if your initial namespace design proves inadequate when you move on to designing your replication or access control framework, or even when you begin to pilot your directory service. Don't be afraid to redesign during these early stages; redesigning later is much more costly.

This chapter is closely related to Chapters 10, Topology Design, and 11, Replication Design. In fact, we suggest that you read all three chapters as a unit because decisions concerning namespace design have direct consequences for your directory topology, which in turn has a direct bearing on your replication strategy.

This chapter introduces the fundamentals of namespace design, starting with a brief review of the syntactic structure of an LDAP namespace, followed by a discussion of the purposes of a namespace. Then we describe how to analyze your namespace needs and design the best namespace for you. Several different namespace designs addressing a varizty of needs and environments are presented near the end of the chapter, followed by a checklist of things to consider when you're designing your namespace.