EDI - Electronic Data Interchange

Of all the business applications of computer networks, this is proving to be the single most important.

What is EDI?

[1] More correctly, of course, we should say "application to application" data transfer


EDI Standards

The basic concept of EDI is that companies agree to a standardised format of EDI messages which are then unambiguously exchanged using a reliable, connection-oriented computer network delivery service.

There have been two proposed EDI standards:

ANSI X.12
developed in the US and widely adopted, although not an international standard[2]. Will eventually (post-1995?) be replaced by:
EDIFACT
(EDI For Administration, Commerce and Transport), originally developed by the U.N. (?) and submitted to ISO for ratification as an international (and hence Australian) standard.
In EDI, an interchange is made up of one or more messages (or possibly functional groups containing messages of the same type), which in turn are composed of segments built up from one or more single or composite data elements.

[2] Nevertheless, Stallings & Van Slyke (and others) only describe the US-centric ANSI X.12 standard...:-(


EDI Data Structures

An EDI message is the basic unit of transmission - typically a message can consist of an order, an invoice or a similar business document.

Original diagram from Standards Australia, AS 3801 - 1989


Typical EDIFACT Messages

Some EDIFACT message types:
CREADV
Credit Advice
CREEXT
Extended Credit Advice
CUSDEC
Customs Declaration
DEBADV
Debit Advice
IFTMAN
Arrival Notice
IFTMBC
Booking Confirmation
IFTMBF
Firm Booking
IFTMFR
International Forwarding & Transport Message Framework
INVOIC
Invoice message
ORDERS
Purchase Order
PAYORD
Payment Order
REMADV
Remittance Advice
and many, many more ...

There are also a larger number of draft and proposed message types awaiting standards approval. It is possible for a group of users to suggest a new message type to meet an unusual business need.


EDI Implementation

There is a great deal of flexibility in the way EDI can be implemented. Some approaches include:

  1. Use of a commercial EDI provider service, whereby users establish a permanent or dial-in link to the provider who in turn provides a "mail box" where messages are lodged to await delivery to the recipient. The principle disadvantage of this occurs where messages must be relayed to recipients connected to a different EDI service.
  2. Use of a commercial electronic mail facility such as the OSI X.400 service offered by Telstra - the advantage of this over option 1. is that X.400 delivery is somewhat more universally available.
  3. Delivery using the reliable transport service of the Internet - either using the TCP protocol directly, or indirectly by encapsulating EDI messages into SMTP electronic mail. This is the obvious choice for future EDI users, the only lingering concerns having to do with security.

EDI System Architecture

Key system entities include:
Application Software
is where the business information is created and used - eg: order entry and accounts payable systems.
Translation Software
is required to convert internal representation of data to and from the standard formats used in EDI. This can usually be supplied by the EDI provider as part of a complete PC-based turnkey package.
Note: such PC-based translation software is regarded as suitable for small businesses starting out with EDI. However:

EDI Security

Some concerns include:

For X.400-based systems, security is built in, and may be sufficient to meet the user's requirements. However, if it is provided as part of the X.400 service instead of by the end-users, there could be a cause for concern.

There is little inherent security in the Internet. The EDIFACT group has addressed these concerns, and have (apparently) released trial standards for security mechanisms within the EDI specification itself.


Case Studies and the EDI Industry Group

Major Australian EDI users include: The Australian EDI industry body is the "EDI Council of Australia", EDICA. Their brief also covers other forms of electronic messaging such as: NB: EDICA also states "Many organisations, particularly those with over $100 million in sales have already begun full scale trading partner initiation programs. Very few have achieved successes which they would consider to be commensurate with the time, effort and money expended"
This lecture is also available in PostScript format. The tutorial for this lecture is Tutorial #19.
Phil Scott