RFC 1309 (rfc1309) - Page 2 of 16
Technical Overview of Directory Services Using the X
Alternative Format: Original Text Document
RFC 1309 Technical Overview of X.500 March 1992 communicate with another person, PROVIDED THAT YOU KNOW HOW TO REACH THEM. Thus, along with the expansion of the telecommunications infrastructure came the development of Directory Services. In this paper, we will discuss various models of directory services, the limitations of current models, and some solutions provided by the X.500 standard to these limitations. 2 MODELS OF DIRECTORY SERVICES 2.1 The telephone company's directory services. A model many people think of when they hear the words "Directory Services" is the directory service provided by the local telephone company. A local telephone company keeps an on-line list of the names of people with phone service, along with their phone numbers and their address. This information is available by calling up Directory Assistance, giving the name and address of the party whose number you are seeking, and waiting for the operator to search his database. It is additionally available by looking in a phone book published yearly on paper. The phone companies are able to offer this invaluable service because they administer the pool of phone numbers. However, this service has some limitations. For instance, you can find someone's number only if you know their name and the city or location in which they live. If two or more people have listings for the same name in the same locality, there is no additional information which with to select the correct number. In addition, the printed phone book can have information which is as much as a year out of date, and the phone company's internal directory can be as much as two weeks out of date. A third problem is that one actually has to call Directory assistance in a given area code to get information for that area; one cannot call a single number consistently. For businesses which advertise in the Yellow Pages, there is some additional information stored for each business; unfortunately, that information is unavailable through Directory Assistance and must be gleaned from the phone book. 2.2 Some currently available directory services on the Internet. As the Internet is comprised of a vast conglomeration of different people, computers, and computer networks, with none of the hierarchy imposed by the phone system on the area codes and exchange prefixes, any directory service must be able to deal with the fact that the Internet is not structured; for example, the hosts foo.com and DISI Working Group
