IBM Cloud Functions is a service provided by IBM Cloud. It is powered by Apache OpenWhisk; actually, it's IBM who donated OpenWhisk to the Apache Foundation. We have a chapter dedicated to OpenWhisk later in this book.

The Cloud Functions service provided by IBM is, of course, very similar to other function services in terms of concepts. Functions wrap around the application business logic and run in the event-driven FaaS environment managed by IBM.

Functions are designed to respond to a direct HTTP invocation from other Web or mobile apps, or to events triggered by other supported systems, for example, Cloudant. IBM Cloud provides Cloudant, a commercially supported JSON data store built on top of CouchDB.  We can prepare a trigger in the Cloudant system, and let it fire events to invoke functions defined in the IBM Cloud Functions, when the data in Cloudant is changed.

The design goal of functions is generally the same among cloud providers. They provide a way for us developers to focus only on writing application business logic, then uploading codes to their cloud as cloud functions.

To further explore the concepts behind OpenWhisk, the engine behind IBM Cloud, please feel free to jump to Chapter 6, OpenWhisk on Docker, to learn more about OpenWhisk.