CM Crossroads recently published this API Testing article by Parasoft's Wayne Ariola and Cynthia Dunlop....
Imagine you're looking to get a used car for your teenage daughter. Ideally, a trusted friend or relative is willing to give you a great deal on a hand-me-down that you know they've treated with care. You see if your daughter likes it, then give it a test drive. If it seems like a good fit, you're all set.
Now imagine that nobody you trust is looking to unload a car right now. Are you comfortable putting your daughter in a car that you found from an independent seller on Craigslist? Or would you rest easier if you set her up with a certified preowned vehicle—something that passed a reputable dealer's one hundred fifty-point quality assurance inspection and was backed with a five-year bumper-to-bumper warranty and roadside assistance?
With service-oriented architecture (SOA), as with the hand-me-down car from a close friend or relative, the element of trust is key. Because you're familiar with the "supplier," you're not so worried about the quality of the product. You can reasonably assume that certain standards have been met, and you're comfortable moving forward without extensive vetting.