Well, "enterprise" software does have APIs in the form of EDI protocols. http://en.wikipedia.org/wiki/Electronic_data_interchange http://en.wikipedia.org/wiki/

Well, "enterprise" software does have APIs in the form of EDI protocols. http://en.wikipedia.org/wiki/Electronic_data_interchange http://en.wikipedia.org/wiki/Electronic_data_interchange Admittedly they're not perfect, but "hackers" weren't the first ones to think of automating back office processes. Most invoicing, payables, receivables etc. happen over these protocols. Naturally these functions will probably eventually move to REST over time as the broader enterprise software ecosystem moves in that direction, but it's not like wild uncharted territory.