EDI As A Railroad
It is like the U.S. Freight rail system. Both take your product; pack it in their own container (envelopes/files; box cars); move it to the recipient by a network of rails or phone:data lines (both built by private companies); switch from one to the other (no single VAN or railroad covers the whole country....yet); and finally deliver to the recipient (rail siding or VAN mailbox).
A VAN lets you complete all your transactions in one transmission. A train lets you send all your shipments at once.
The VAN is essentially a giant virtual switchboard where data is shunted from one participating company to another. The rail system is essentially a giant virtual switchboard where freight is shunted from a participating shipper to a customer.
A VAN is a company offering the communications skills, expertise, and equipment needed to communicate electronically. In an EDI context, a VAN acts like an electronic post office by receiving, storing, and forwarding electronic messages. A company and its trading partners have "mailboxes" on the VAN where EDI transactions can be stored. A railroad is a company offering the transportation skills, expertise, and equipment needed to move your products. At one point, railroads moved most of the mail for the post office.
Both VANs and railroads use “Service Messages” to track “shipments”. Ironically, railroads use a series of EDI transmissions to do the tracking.
The term mailbox is used to refer to a unique identified area of information storage within a computer, a point of private user access and data consolidation to which EDI transmissions are sent and held until retrieved by the individual EDI VAN customer. Each VAN participant can retrieve documents from its assigned mailbox whenever convenient to it's own operations. Well, that is like a railroad siding. The customer can open the door and unload when he is ready.
We used a VAN for simplicity in explaining the process, but newer technologies are becoming more popular. The file is sent to either a VAN mailbox, FTP site, or directly to AS2 recipients to be picked up.
Railroads are in the 21st Century too: ever hear of a UNIT TRAIN? Remember those wooden control towers alongside railroads? They are replaced by large centrally located electronic control towers.
Yes, sometimes we go outside the system. Internet EDI goes over the “Internet” (who owns or built the Internet?). Non-rail truck traffic goes over the highway system (guess who pays for our highways).
Now for a ridiculous story or two. Several years ago the NY Central Railroad and the Pennsylvania Railroad merged into the Penn Central Railroad. Many shippers’ box cars got lost going between stations on the Penn Central. A few ytears ago INOVIS and GXS merged. Many customers lost data going between these two entities.