In the past decade, LDAP directories have risen from a relatively obscure offshoot of an equally obscure field to become one of the linchpins of modern computing. Increasingly, LDAP directories are becoming the nerve center of an organization's computing infrastructure, providing naming, location, management, security, and other services that have traditionally been provided by network operating systems. Design and deployment of a successful LDAP directory service can be complex and challenging, yet little information is available explaining the ins and outs of this important task.

When two of us (Mark and Tim) finished writing a previous book, LDAP: Programming Directory-Enabled Applications with Lightweight Directory Access Protocol, in early 1997, we soon realized there was another, much bigger piece of the directory puzzle still to be addressed. The previous book was aimed at directory application programmers, but nothing similar was available to address the needs of directory decision makers, designers, and administrators. This book is aimed at that audience.

Recognizing the size of the task ahead of us and remembering the joys of giving up evenings and weekends for months at a time to meet deadlines for our first book, we quickly decided to expand our team. Just as quickly, we decided there was no one we'd rather share the fun with than our longtime friend and colleague, Gordon Good, at the time a senior directory developer at Netscape. Aside from being the third leg of the LDAP development team at the University of Michigan (U-M), Gordon brought a wealth of system administration experience from his past life as a directory and e-mail administrator and Web master for U-M. With Gordon on board, the three of us set about writing a book that we only half-jokingly referred to as the "LDAP Bible." The first edition of Understanding and Deploying LDAP Directory Services was published in 1999.

Two years later, we realized that it was time to update this book and publish a second edition. LDAPv3 work in the IETF was mostly complete. Numerous extensions to the basic LDAP protocol were being developed. LDAP support in commercial and open-source software was widespread. In this edition, we cover these recent directory services developments. In addition, in response to reader suggestions we have streamlined the text, added more hands-on examples, updated the examples to reflect currently available software versions, and updated the case studies to reflect current directory practice. We thank all the readers of the first edition who provided helpful suggestions, and we hope that you find this second edition even more valuable.

The Book's Organization

This book includes 26 chapters in 6 parts. Part I introduces directories and LDAP. Parts II through IV each address a different part of the directory life cycle. Part V discusses how to leverage your directory service after it's up and running. Finally, Part VI presents three directory services deployment case studies.

Part I, Introduction to Directory Services and LDAP, provides a comprehensive introduction to directories and LDAP. For readers unfamiliar with the topic, this section should bring them up to speed and provide the background necessary to understand the rest of the book. It also includes a section on the history of directories for readers interested in how all this technology came about.

Part II, Designing Your Directory Service, begins to delve into the directory life cycle by covering the first, and in many ways most important, phase: design. We cover all aspects of directory design, from determining your needs, to designing your data sources, schema, namespace, topology, replication, and finally privacy and security.

Part III, Deploying Your Directory Service, covers the next phase in the directory life cycle: deployment. We cover everything from choosing the right directory products to piloting your service to putting your service into production. We've also included a chapter about analyzing the cost of your service and how to help reduce those costs.

Part IV, Maintaining Your Directory Service, concludes our coverage of the directory life cycle with a look at the maintenance phase. We cover such topics as backups and disaster recovery, maintaining data, monitoring your directory system, and troubleshooting problems when they occur.

Part V, Leveraging Your Directory Service, talks about how to take advantage of the service you have designed and deployed. We discuss how to directory-enable existing applications, how to create new applications that use the directory, and how your directory can coexist with other data sources.

Part VI, Case Studies, closes the book by presenting several directory case studies. Some of the case studies presented are real, and some are fictitious, but all are designed to illustrate the concepts of directory design, deployment, and maintenance in action.

The Book's Audience

This book is intended for primarily three kinds of readers: decision makers, architects, and administrators. In addition, anyone who wants to know more about LDAP or directories in general will find the book useful, as will software engineers who develop directory applications.

Directory decision makers will find this book useful for aiding an understanding of directories and the kinds of business problems they help solve. Decision makers will find Part I useful for explaining the basics of directories. Part VI should also prove useful by providing some realistic examples of how directories are used and the benefits they can bring.

Directory architects will find this book useful in defining the design problem and providing a methodology for producing a comprehensive directory design. The design methodology is focused on a practical approach to design based on real-world requirements. We highly recommend that directory architects and designers read the whole book, paying special attention to Parts II, III, and IV. A good directory design results in large part from a clear understanding of the other aspects of the directory life cycle and how the directory will be used.

Directory administrators will find Part IV especially useful. It focuses on the maintenance phase of the directory life cycle, where administrators spend much of their lives. We also highly recommend that administrators read the rest of the book to get an idea of the directory big picture, as well as to understand some of the directory design decisions that are bound to make their lives either miserable or enjoyable.

Other interested readers can pick and choose from the sections of the book that interest them. We encourage all readers to at least skim Part I, to ensure that they have the background required to benefit from the rest of the book. We've tried to structure the book so that each chapter stands by itself as much as possible. Readers should be able to read the chapters covering topics that interest them, without wading through chapters of less interest.

Finally, we think all readers will find the case studies presented in Part VI interesting. They give different perspectives on directories designed to illustrate the trade-offs that different directory needs imply.

Contacting Us

If you have comments or suggestions about this book, or if you'd like to tell us about an interesting directory deployment or application you've developed, we'd like to hear from you. Feel free to drop us a line at the following addresses:

Tim Howes: howes@opsware.com
Mark Smith: mark@bradesmith.com
Gordon Good: ggood@opsware.com

We'll try our best to get back to you, but keep in mind that we all have day jobs!