Communications support for EDI

There are many parallels between passing structured commercial messages between computer systems (which is the objective of EDI communications) and passing unstructured text between users´ terminals (which is the objective of electronic mail, commonly referred to as E-mail). The implication of EDI facilities is by interpretation of structured information in a header section of each message or group of messages. This structuring must conform to a syntax such as EDIFACT or ANSI X.12, and the central store must be programmed to recognise the syntax in use by the communicating computers. Thus, a store and forward system for the support of EDI is programmed differently from those for the support of inter-personal E-mail. The number and variety of different systems for carrying interpersonal messages, including E-mail, telex, teletex and facsimile amongst others, has prompted the development of a set of standards for linking all such systems, and has been published by the CCITT as the X.400 Recommendations. The question must now be asked, why use X.400 for carrying EDI? The commercial situation regarding the number of different suppliers of EDI Value-Added Services is similar to that regarding E-mail service suppliers, with three major operators and limited facilities for interconnecting them. Work has been carried out within the CCITT on a new X.400 protocol known as Pedi that will enable EDI messages to be carried over X.400 systems without losing the communications functions needed to make EDI effective and useful. This work has resulted in two new recommendations (F.435 specifying the service and X.435 specifying the protocol) and the way is now open for practical implementation. The author considers the nature of the problems and their solution