The next time you hear the voiceover on an Apple iPhone ad say, “There’s an app for that,” remember that there are also two, three, or more application programming interfaces (APIs) for each of those highly advertised 70,000-plus individual iPhone apps. APIs are the glue that hold both consumer and enterprise software together and let consumer/enterprise software talk to other consumer/enterprise software. In fact, because of APIs, the distinction between enterprise and consumer applications will fade away, in my opinion.

And remember that that same app you saw on the iPhone ad or something very similar to it supporting the same company or consumer need is probably also available on msn.com, Mapquest, Facebook (or MySpace or LinkedIn — depending on your generation).  Multiply each site by the number of APIs involved by the number of mobile phones and PCs and Blackberrys and kiosks and ATMs and …

I did all that arithmetic while Sam Ramji was explaining to me recently why he left a high-level position at Microsoft in September to become vice president of strategy at Sonoa. When I first saw the Sonoa press release about Sam, with whom I had last met when he was planning BEA Aqualogic, I couldn’t figure out how a company could make any money selling computer-science abstractions such as APIs.  I quickly found out that Sonoa is not selling APIs, but selling all aspects of managing the use of APIs.

Sonoa’s software-as-a-service, which is also available on-premise as an appliance, saves companies from having to rewrite business logic every time they need to expose an API for a different marketing/sales channel. (The number of APIs needed gets higher when you multiply the number of apps times the number of devices, times the number of distribution channels in which a company works). To help me understand it, I think of a company like Sonoa being necessary to support the exponential progression in API quantity and complexity:

• from the dozens of closed APIs that used to be held close to the vest by the DECs and IBMs of the world (except to the extent they made such things visible via Posix but required you to use all their development tools and infrastructure software).
• to the hundred or so APIs that a company like SAP made available to a handful of partners as BAPIs (while requiring certification and requiring the partner to use SAP’s ABAP fourth-generation language tool).
• to the set of APIs that Microsoft made available to thousands of partners via the Windows API (no certification required, but you had to use Windows development tools and infrastructure).
• to the Web/HTML APIs provided by Web sites such as Google and others today (using free Google, etc. tools).
• to the explosion of cloud APIs coming tomorrow (based on free and open-sourced de facto standard tools based on Ruby on Rails, Java, etc.).

Every company that wants to do business in the cloud (and that will be all companies and organizations eventually, just as every business eventually adjusted its business model to dependence on the Web) will be multi-channel by definition and every Web page from which these companies want to advertise, solicit, enable payment, give directions, and so forth will need cloud APIs.  In fact, these companies will not even know everywhere they will appear in the cloud because their advertisements, solicitations, payment terms and conditions, directions, etc. will get "mashed up" by other sites and other apps. But only if their APIs are properly managed.

OK, Sam, now I get it.

(For the record, Sonoa’s flagship offering, ServiceNet, helps companies as diverse as MTV, IMG and Guardian Insurance open and manage their services to the cloud via APIs. Sonoa also recently introduced another offering for API developers called Apigee (www.apigee.com) that provides free analytics for APIs.)