Traditionally, EDI data exchange runs within what are known as Value Added Networks (VAN). A VAN is defined as a secure private network in which EDI documents can be sent and received between partners. Each partner receives their own mailbox from which the documents are sent and received. Every partner regularly checks their mailbox to pick up received documents. VANs are very secure, but are subsequently the most expensive transmission channel.
The establishment of the internet and secure transmission protocols (such as AS2, HTTPS) has resulted in increasingly more EDI data being directly exchanged via the internet between partners or via EDI service providers. Internet-based communication via AS2 requires two computers consisting of one client and one server, directly connected to one another via the internet. AS2 creates an EDI envelope for a message, which is sent securely over the internet with the help of digital certificates and encoding.
A Virtual Private Network (VPN) generally uses the internet and a number of specialised protocols to secure data communication. Generally, a client/server configuration is used in which VPN clients authenticate the users, encode the data and manage sittings with VPN servers. Since the encoding makes the data packages virtually useless on their path between the sender and the recipient, and the transmission only decoded at its beginning and end, this scenario is also sometimes described as a “VPN tunnel” through the internet.