EDI requires :
This web site gives an overview of the methods involved in the physical sending of EDI data.
Just as message syntax requires some form of standardisation, so do the lower levels of communication carried out between the computer systems and network facilities used by different trading partners. The reason is that many companies communicating across a network have widely differing machines and software.
A single dedicated connection between one system and another is acceptable while there are only two systems trying to communicate. When there are interconnections between several companies, things become more complex and more expensive.
A company which connects with several trading partners will need to set up appropriate conversion facilities for each of them if they all have different computer systems.
This problem can be reduced if the companies involved use a communication method which adheres to a common standard. Nevertheless, there are several possible communication methods, all of them having their own advantages and disadvantages, as described in the following pages.
OFTP is now used by most major European Motor Manufacturers and their suppliers. It is also used by the chemical industry, white goods manufacturers and is currently being adopted by other sectors such as banking.
The OFTP (ODETTE File Transfer Protocol) provides a standardised way for separate computer systems to communicate with each other.
The OFTP is a high level protocol. It is applied to the way messages are sent rather than the physical communications line across which they travel.
The basic physical connections are also standardised but these are covered by other protocols such as X.25, TCP/IP and ENX extranet.
Point-to-point communication is the direct communication between trading partners using either:
The direct leased line is suitable for dedicated trading partner application only. The line is available 24 hours a day, but by nature is quite costly.
The dial-up Public Switched Telephone Network can be accessed by using a modem.
The modern transmissions are based on the advanced networks of transmission susch as:
A VAN can be thought of as a mailbox facility. A company sends data via a VAN which is "addressed" to a trading partner. The message is sent to the appropriate "pigeon hole" where it can later be picked up by the intended receiver, i.e. store and forward facility.
The advantage of this approach is that the VAN is supporting all available protocols so trading partners using EDI need not implement software supporting the same protocol as the companies with which they exchange data.
The other advantage may be that several messages addressed to different trading partners can be sent in one transmission because there is only one immediate receiver - the VAN. On the other hand EDI software supporting point-to-point communication can transmit files to different trading partners without any manual intervention, once the communication parameters have been configured at time of implementation.
In some countries VAN services are by tradition frequently used by the automotive sector. Other countries rely primarily on point-to-point communications based on X.25 and OFTP or ISDN and OFTP.
To control the communication of data, OFTP provides a set of signals which indicate when a message can be sent to the receiving system. These signals are called the OFTP commands. Each command serves a different function, not all of which will be used in every transmission – the signals used will be dictated by the nature of the communication session itself.
OFTP allows the transfer of different types of files. These include fixed length records, variable length records, unformatted files and text format files.
OFTP supports TCP/IP, ISDN, direct native access to the X.25 network, dial-up connections using a combination of recommendations X.28, X.3 and X.29. It provides both error detection and recovery procedures for the latter. As well, ISDN connection to X.25 networks can be used in accordance with recommendation X.31.
OFTP is perfectly adapted to ENX extranet; certified ENX operators offer various types of connections (isolated station with IPsec customer, connection by STN or ISDN: up to 64 kbits, small LAN, LAN...). See ENX file...
Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide communications security over the Internet.
Strong authentication is a mechanism to ensure mutual identification of two network partners. This mechanism is based on the personal character of the private key.
Services file, defined by the protocol version 2, provide optional services:
Start Session Ready Message.
This is the first command to be sent after a connection has been requested, indicating that the application is communicating with another OFTP.
Start Session IDentification.
This is a request for initiate a session. It contains information such user and password of the requester.
Start File Identification.
This is a request for permission to send a file. It contains information such as the origin and destination of the file, its name and physical size.
Start File Positive Answer.
This is a positive acknowledgement for SFID request. Transfer is accepted.
Start File Negative Answer.
This is a negative acknowledgement for SFID request. Transfer is rejected.
The actual file data sent to the trading partner.
Set CreDiT.
Service command for flow control.
End of File IDentification.
This command is sent immediately after the file has been transferred containing control totals to ensure the integrity of the sent file.
End File Positive Answer.
This is a positive acknowledgement for EFID request. Transfer is succesfully completed.
End File Negative Answer.
This is a negative acknowledgement for EFID request. Transfer is cancelled.
End to End ResPonse.
The EERP is generated when a file reaches its ultimate destination. It is sent to the originator of the file to inform them that the file has been received.
Negative End ResPonse.
The NERP is generated when a file cannot be transmitted to its ultimate destination. It is sent to the originator of the file to inform them that the file cannot be transmitted
End of Session IDentification.
The ESID requests that the communication session be terminated.
Change Direction.
The CD command gives token to partner.
Ready To Receive.
The RTR command is an acknowledgement for EERP. It permits flow control.
Security Change Direction.
The SECD command asks partner to send an AUCH command. It is used for initializing authentication sequence.
Authentication Challenge.
AUCH command is sending of an authentication challenge, i.e a random string encrypted wit partner's public key. It is used for strong authentication...
Authentication Response.
AURP command is the answer to AUCH; command carries the decrypted challenge
Face to the needs of communications between the different partners of the automotive industry (manufacturers, equipment suppliers...) which increase more and more, a specific extranet dedicated to this industry has been developed: ENX (European Network eXchange).
This extranet accelerates, develops and standardizes the division and the exchanges between the various actors of this sector. Indeed, ENX provides a common platform of communication. Global, open and secured, this platform allows to exchange any type of application : from CAD files - at the base of this extranet – to EDI files and interactive applications...
For interconnections, ENX extranet uses Frame Relay networks, ISDN, and IP which guarantee the speed of the band-width - availability, safety and quality of the connection services.