What Are Events?

To understand event-driven-architecture (EDA), you first need to understand events.

In the simplest terms, an event is something that happens. In IT terms, an event represents a change in the state of data, such as a sensor signaling a change in temperature, a field changing in a database, a ship changing course, a bank deposit being completed, or a checkout button being clicked in an e-commerce app. Often, the sooner an enterprise knows about an event and can react, the better.

When an event happens, an application sends a message. A message is simply a communication of data. In an EDA, messages communicate data about events.

Events and messages are so closely related in an EDA that people often refer to the message generated to communicate the event data as an event rather than what happened to generate the event message.

For large enterprises who need to track and respond to constantly occurring events as vehicles and goods move, prices change, and customers click, EDA provides an infrastructure for making sure that streams of event messages get everywhere they need to go as quickly as possible to enable enterprises to act on new data in near-real-time.

For in-depth information about events and messaging, see Understanding Events and Messaging.

The remaining topics provide an overview of the event messaging and message routing technology in the PubSub+ Platform to help you further understand EDA.

To learn more, move on to What Is Messaging?