Serverless and event-driven collision

Event-driven computation is an architecture pattern that emphasizes action in response to or based on the receptions of events. This pattern promotes loosely coupled services and ensures that a function executes only when it is triggered. It also encourages developers to think about the type of events and responses a function needs in order to handle these events before programming the functions: 

A system built with event-driven architecture consists of Event Producers that produce a stream of events that are ingested using Event Ingestion, and then Event Consumers that listen for the events, as shown in the preceding diagram.

Events are delivered to consumers in near real time so that they can respond immediately to the events as they happen. Event producers are decoupled from the event consumers. As they are decoupled, the producers don't know which consumers are listening to the events that they produce. Event consumers are also decoupled from one another, and every event consumer sees every events produced by the event producers.

Serverless applications are usually built by combining multiple functions (FaaS) using offerings, such as AWS Lamdba or Microsoft Azure Functions, together with external backend resources, such as Amazon S3, Amazon DynamoDB, and many more solutions to manage the state between invocations. The architecture that ties these multiple functions (FaaS) is event-driven architecture. By combining tools, such as AWS Lambda and Amazon S3, you can develop applications without having to think about the provision and management of the infrastructure. As this is a shift in architecture compared to how you might have operated so far, you would also need to change how data will flow through your application, which is made up of functions.

In this event-driven architecture, the functions are event consumers because they are expected to come alive when an event occurs and are responsible for processing it. Some examples of events that trigger serverless functions include the following:

• API requests
• Scheduled events
• Events in object storage
• Events in databases
• Notification events