e-Commerce Gate Way is the one of the Module in Oracle Apps. EDI (Electronic Data Internchange) is way of exhchanging the Business documents like Sales Order Invoice PO etc. between two business entities in agreed standard format like ASCII X12 format. In oracle application business documents may be refered as 850POI(purchase order Inbound) 810INO(Invoice Outbound) etc..
There are several third party sources are available which may be use in mapping of several documents from Oracle Format to X12 and vice versa. Some of them like Sterling Commerce Kleinschmidt ....