Current Trends in EDI and X.400
- O. Greevy
- in: Bulletin Technique, Swiss PTT Telecom,
the database will become very large (there are currently in excess of 1 million entries), it can be distributed over a worldwide network of Directory System Agents (DSAs) each of which holds a small portion of the total information.Information is held in objects which have a number of mandatory and optional attributes. To facilitate the storage of diverse forms of information, a hierarchy of object classes has been defined and inheritance can be used to define new classes that contain all attributes of their parent object classes. Some examples of object classes include: person, organization, and country.The directory is interrogated by employing a Directory User Agent (DUA), which contacts its nearest DSA and interrogates it using a standardised access protocol (DAP). If the DSA is not holding the information locally, it can obtain it from a neighbouring DSA that is holding either the master copy of the information or a slave/cache copy. A key feature of the system is that DUAs operating in Electronic Data Interchange is the means by which companies exchange trade-related documents between application processes in electronically processable form. The initial development of this technology has been hampered by the lack of accepted international standards. One of these standards is X.500 for directory services. X.500 can be used as a powerful tool in allowing electronic data interchange to take place between companies without the necessity for prior agreement. The article describes a mechanism by which the directory can be used to store product information that may be used by a purchaser in ordering electronically.