Before diving into the different ways in which you can provide APIs to those integrating or extending your application, let's review these needs through the eyes of Developer X. This is the name I give to a persona representing a consumer of your APIs and general integration and extensibility requirements. Much like its use in designing a user interface, we can use the persona concept to sense check the design and interpretation of an API.
Asking a few people (internal and external to the project) to represent this persona is well worth doing, allowing them to provide use cases and feedback to the features and functions of your application's API strategy, as it is all too easy to design an API you think makes sense, but others with less knowledge of the application do not easily understand. A good way to develop a developer community around your API is to publish designs for feedback. Keep in mind the following...