Software Architect's Handbook

Function as a Service (FaaS)

In a serverless architecture, a small piece of code, like a function, can be executed using an ephemeral compute service to produce a result. This is known as Function as a Service (FaaS). By ephemeral, we mean that it will only last for a limited amount of time. The code executes in a container that is spun up on invocation and then brought back down when it is complete.

Functions are typically invoked due to events or HTTP requests. When a function completes its processing, it can either return a value to the caller or pass the result to another function that will be invoked as part of a workflow. The output can either be structured, such as an HTTP response object, or unstructured, such as a string or an integer. ...