Faas

FaaS, or Function as a Service, is a cloud computing execution model that allows developers to deploy individual functions that run in response to events. Functions are typically stateless, execute in isolated runtimes managed by a cloud provider, and are billed based on the number of invocations and the time taken to run.

In a FaaS setup, an event source—such as an HTTP request, a message on a queue, or a file system change—triggers the corresponding function. The platform handles provisioning, scaling, and isolation between invocations, and can automatically scale to handle bursts of events. Developers write small, purpose-built units of code in supported languages.

Functions are designed to be short-lived, with runtimes often offering configurable memory and execution time limits. They are typically stateless, with any required state stored in external services. Because deployments are event-driven, FaaS commonly integrates with API gateways, event buses, storage services, and databases to form serverless applications.

Common use cases include building HTTP APIs, processing data streams, real-time transformation of data, scheduled tasks, image or video processing, automation workflows, and IoT event handling.

Advantages include reduced operational overhead, automatic scaling, and potential cost savings for irregular workloads. Limitations encompass cold-start latency, constraints on execution duration and memory, potential vendor lock-in, debugging and observability challenges, and the need for external storage for state.

Notable platforms include AWS Lambda, Microsoft Azure Functions, Google Cloud Functions, and IBM Cloud Functions (built on Apache OpenWhisk). Open-source alternatives include OpenFaaS and Fn Project, which allow running FaaS on-premises or in other clouds.