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9

Directories – More Than

Just Information Storage

9.1 Introduction

Directories are rapidly becoming the cornerstone to delivering flexibility

for advanced services, both as means of storing location information, user

configuration and resource privileges and as a means of storing service￾specific information allowing for rapid provisioning of customers and

rapid modification of services. One of the key issues that directories

will resolve for the next-generation networks is the dynamic nature of

the future services and the desire to reach services based on useful text￾based naming.

In the previous chapter on representing information we explored a

number of exciting uses of Extensible Markup Language (XML) to

allow applications to discover and use services, none of this discovery

process would work without directories.

I start this chapter with a brief look at the domain name system (DNS),

possibly the best-known directory system, since most of us use it every

day. I continue the chapter by looking at X.500 and Lightweight Directory

Access Protocol (LDAP). X.500 is the International Telecommunications

Union (ITU) standard for directory technologies and whilst complex is

arguably the most influential of all the directory technologies. We then

take a look at the concept of meta-directories, directory systems that link

other directories together.

Next Generation Network Services

Neill Wilkinson

Copyright q 2002 John Wiley & Sons, Ltd

ISBNs: 0-471-48667-1 (Hardback); 0-470-84603-8 (Electronic)