You need a way to move EDI messages from one organization to another. It is usually accomplished using one or more of the following techniques:
In the most basic form, a (Valued Added Network) VAN acts as a regional post office. They receive transactions, examine the 'From' and the 'To' information, and route the transaction to the final recipient. VANs provide a number of additional services, e.g. retransmitting documents, providing third party audit information, acting as a gateway for different transmission methods, and handling telecommunications support. Because of these and other services VANs provide, businesses frequently use a VAN even when both trading partners are using Internet-based protocols. Healthcare clearinghouses perform many of the same functions as a VAN, but have additional legal restrictions that govern protected healthcare information.
VANs also provide an advantage with certificate replacement in AS2 transmissions. Because each node in a traditionally business-related AS2 transmission usually involves a security certificate, routing a large number of partners through a VAN can make certificate replacement much easier.
Until recently, the Internet transmission was handled by nonstandard methods between trading partners usually involving FTP or email attachments. There are also standards for embedding EDI documents into XML. Many organizations are migrating to this protocol to reduce costs. For example, Wal-Mart is now requiring its trading partners to switch to the AS2 protocol.
AS2 (Applicability Statement 2) is the draft specification standard by which vendor applications communicate EDI or other business-to-business data (such as XML) over the Internet using HTTP, a standard used by the World Wide Web. AS2 provides security for the transport payload through digital signatures and data encryption, and ensures reliable, non-repudiable delivery through the use of receipts.