Every day, companies around the world are migrating applications to the Web and expanding the potential of their businesses in the process. It's about more than cutting costs and increasing access -- it's about rethinking the possibilities of your business. Forget incremental improvement -- Web deployment can give your apps power and flexibility you never dreamed of. You may find your business reinvented, your industry in a paradigm shift, and, in another bonus of Web migration, a way to get rid of EDI. EDI: The ultimate legacy app
EDI has been a staple of my career for 12 years and I don't remember ever really enjoying it. The same difficulties, barriers, implementation headaches, and user grumbles are always present. It also curtails innovation by requiring an extremely rigid adherence to accepted convention. In the end, you're happy just to have it working at all, and all parties involved in an EDI chain generally heave a sigh of relief when the lowest common denominator is satisfied. Lofty EDI goals almost never are met. It works like this:

• Company A wishes to issue a purchase order (PO) to Company B. Company A's system generates the PO, which now resides in its database, and copies it into a convenient flat-file format.
• Company A converts the flat-file PO into EDI format, a very specific variable-length string of delimited values, with an EDI translation package. A header and trailer are attached, addressing the string.
• Company A accesses a value-added network (VAN), a proprietary data communications network that hosts a mailbox system for EDI users. Oops! Company B uses a different VAN, so VAN A hands off the PO to VAN B. It's stored in Company B's mailbox. (As a side feature, one of the VANs might screen the message for standards compliance; this is sometimes offered by VANs and used by EDI trading partners, though most EDI translators perform this same function.)
• Company B retrieves messages from its mailbox, including Company A's PO. It automatically generates an EDI message back to Company A along the same route; this message simply acknowledges receipt of the PO.
• Company B's EDI translator converts the PO back into flat-file format. It is imported into Company B's database and, consequently, into its order-processing system.
• Company B generates an invoice in flat-file format from its database. Internally, it ties the invoice to the original PO.
• Company B submits the flat-file invoice to its EDI translator, generating a similarly formatted EDI string, addressed back to Company A.
• Company B accesses its VAN and fires off the invoice, which jumps VANs and winds up in Company A's mailbox; Company A retrieves it, then generates an acknowledgement, which is sent back to Company B.
• At some point in both systems, POs are reconciled to invoices, and acknowledgments are reconciled to the documents they refer to.

This is a very simple example of EDI exchange. PO changes, advance ship notices, promotion documents, and other EDI messages make the whole system much more complex than this bare-bones exchange.