[blantonl]

*myth of backwards compatible"

What is the "myth" of backward compatible?

I wholeheartedly agree with your second paragraph regarding versions and kill dates - but every API is different. In our case, when our API changes/versions/deprecates - WE are directly held responsible by customers of consumers of the API - since API consumers trumpet the fact that they have integrated with our API.

On the surface, versioning and kill dates are great end-all solutions, but the reality is API consumers have a ton of leverage when your API is successful at generating revenue for you. Especially when those consumers are sending lots of revenue your way from their own customers, which think you are the source.