| The fact that you picked up this book and started to read it suggests that you have some idea what a directory service is and what it can do for you. This chapter assumes that you have an everyday understanding of directories and expands on that notion to answer three simple but important questions -
What is a directory? In brief, a directory is a specialized database. In this chapter you'll learn what makes a directory specialized, what separates it from a traditional database, what the defining characteristics of a directory are, and why they are important. -
What can a directory do for you? Directories can do many things, and you probably chose this book with a particular set of problems in mind that you'd like a directory to help you solve. We'll take you through the basic uses of a directory, many of which may have already occurred to you, as well as cover some more advanced uses that may be new to you. -
What isn't a directory? The answer to this question is sometimes even more important when you're defining a successful directory environment than when you're learning what a directory is. In this chapter you'll learn what separates a directory from a file system, a Web server, and other things you have deployed on your network. The distinctions drawn here are crucial to narrowing the task of designing your directory service. This chapter aims to answer each of these questions in detail, formalizing the answers to give you a common understanding of the task before you design a directory service. You'll learn why directories are important, what the scope of a directory solution is, and what directories can do for you. Near the end of the chapter, we introduce the Lightweight Directory Access Protocol, LDAP, by exploring its history and origins. Armed with this knowledge, you'll be ready to read the rest of the book, which deals with the details of understanding, designing, deploying, maintaining, and using your own directory service. Directory Service Defined This book uses many terms that may be new to you. A directory service is the collection of software, hardware, processes, policies, and administrative procedures involved in making the information in your directory available to the users of your directory. Your directory service includes at least the following components : -
Information contained in the directory -
Software servers holding this information -
Software clients acting on behalf of users or other entities accessing this information -
The hardware on which these clients and servers run -
The supporting software, such as operating systems and device drivers -
The network infrastructure connecting clients to servers and servers to each other -
The policies governing who can access and update the directory, what can be stored in it, and so on -
The procedures by which the directory service is maintained and monitored -
The software used to maintain and monitor the directory service As you can see, it's quite a list! Some of these components are depicted in Figure 1.1. Generally, we will use the term directory as a synonym for directory service . It's important to keep in mind that your directory is a sophisticated system of components that work together to provide a service. Concentrating exclusively on one set of components without thinking about the others is sure to lead to trouble. Figure 1.1. Directory System Components  | |
