API is the acronym for application programming interface, which is an interface that other software applications can use to access the one that API belongs to. API can also refer to a communication protocol that allows for accessing a particular software application.
Realtime data, apps, and the ecosystem around them is growing exponentially. But we still can’t agree on how we describe the APIs powering this realtime growth. The problem is that there are various ways to describe APIs that provide realtime functionality. Event-driven seems to be the most common descriptor. Gartner has adopted the term, stating that by 2020 50% of all managed APIs will be event-driven. But still today there is no consistency or consensus between what terms like realtime API, event-driven API, or streaming API refer to. Often they’re used interchangeably.
As an engineering team and API provider working on a global pub/sub messaging platform, we work with these ideas everyday. We’ve watched discussions around event-driven architecture, webhooks, and streaming data proliferate. Over the years we’ve thought extensively about the best terminology to use and arrived at what we call the Realtime API Family.