Upgrading and Repairing Networks (5th Edition)

During the 1980s when PCs were first being accepted into the corporate environment, the computer room, which contained large proprietary mainframe or minicomputers, was in control of computer system managers. Simple terminal devices, such as the VT100 (a landmark in computer history itself), were attached to these large computers; access mechanisms, such as user accounts and passwords, along with file protection schemes, were used to control access to data. Applications were managed from a central location, and any interaction between computers was also the domain of computer system managers.

The introduction of the PC gave users the capability of managing their own applications and data files. PC networks were the next logical step, and suddenly computer system managers became network administrators and realized that the chaotic environment that came with distributed management was plagued with many problems.

At about the same time, many large businesses found it necessary to support multiple proprietary computing platforms, based on things such as application availability and maintenance costs. Supporting multiple operating systems and hardware platforms produced a dilemma: Users needed to access data on different computers, and each department (and sometimes each user) required setting up different access control mechanisms. In addition, locating the services (or applications) that each user needed became a complex task.

To try to conquer this collection of proprietary systems and distributed data, the X.500 set of protocols was proposed. X.500 encompassed network protocols as well as a method for storing information about resources, applications, users, and other data so that a network based on different systems could be easily managed. Although the X.500 protocols were never widely adopted, they did lay the groundwork for what was later to become the Lightweight Directory Access Protocol.

I can't remember who said it, but it is true that one of the best things about standards is that there are so many to choose from. This is especially the case when it comes to directory services. What started out as a good idea ”X.500 ”spawned all sorts of development of protocols and services that eventually led to the development of LDAP.