In Chapter 1, The Business Value of APIs, doors were used as a metaphor to articulate the role of APIs in delivering access to enterprise information assets and functionality, or in business terms, business capabilities. However, just like doors, which come in different types, materials, and sizes, often determined by what sort of access they provide, APIs too can be classified in different types.
For example, some APIs might be built with a specific use case in mind and in support of a specific application. Because of this, such APIs can be quite specialized and tailored for the purpose they were built to serve. In order words, they are single purpose and are not suitable for reuse outside the context they were built for.
A common term used to refer to these types of (single-purpose) APIs is Experience APIs, mainly because of their role in enabling applications...