Function as a Service — Technology Wiki

Overview

Direct Answer

Function as a Service (FaaS) is a serverless computing model in which developers write and deploy individual stateless functions that execute automatically in response to specific events or triggers, with cloud providers managing all underlying infrastructure, scaling, and resource allocation.

How It Works

Developers package application logic as discrete, event-triggered functions that run on managed cloud infrastructure. When an event occurs—such as an HTTP request, database change, or scheduled timer—the platform instantiates the function, executes it in an isolated container, and deallocates resources immediately upon completion. Billing occurs only for actual execution time, typically measured in milliseconds.

Why It Matters

Organisations reduce operational overhead by eliminating server provisioning and maintenance tasks whilst achieving automatic horizontal scaling. Cost efficiency improves through per-invocation billing rather than reserved capacity, and deployment velocity accelerates by removing infrastructure dependencies from the development cycle.

Common Applications

Common use cases include processing image uploads and triggering transformations, automating workflow orchestration, handling scheduled data synchronisation tasks, responding to IoT sensor events, and processing API requests with variable traffic patterns. Real-time data processing and webhook handlers represent frequent implementations across financial services and media organisations.

Key Considerations

Cold start latency and execution time limits can constrain performance-critical workloads, whilst stateless function design requirements may complicate applications requiring persistent connections or complex session management. Vendor lock-in and debugging distributed invocations across multiple functions present additional operational challenges.

Cross-References(1)

Cloud Computing

Related in Service Models

Cloud Computing

The delivery of computing services — servers, storage, databases, networking, software — over the internet on demand.

Infrastructure as a Service

Cloud computing model providing virtualised computing resources like servers, storage, and networking over the internet.

Platform as a Service

Cloud computing model that provides a platform for developers to build, deploy, and manage applications without managing infrastructure.

Software as a Service

Cloud computing model that delivers software applications over the internet on a subscription basis.

Serverless Computing

A cloud execution model where the provider dynamically allocates resources, charging only for actual compute time used.

Cloud-Native

An approach to building applications that fully exploit cloud computing advantages like elasticity, resilience, and automation.

Private Cloud

Cloud computing resources used exclusively by a single organisation, either on-premises or hosted by a third party.

Public Cloud

Cloud computing resources shared among multiple organisations and available to the general public over the internet.

Managed Service

A cloud service where the provider handles infrastructure management, maintenance, updates, and monitoring.

Cloud Cost Optimisation

Strategies and practices for minimising cloud computing expenses while maintaining performance and functionality.

Spot Instance

A cloud computing option that uses spare capacity at significantly reduced prices with the possibility of interruption.

Cloud Orchestration

The automated arrangement, coordination, and management of complex cloud computing systems and services.

More in Cloud Computing

API

Architecture Patterns

Application Programming Interface — a set of protocols and tools for building and integrating software applications.

Message Queue

Architecture Patterns

A communication method where messages are stored in a queue until the receiving application can process them.

Spot Instances

Service Models

Spare cloud computing capacity offered at steep discounts compared to on-demand pricing, available when the provider has excess resources but subject to interruption.

REST API

Architecture Patterns

An API architectural style using HTTP methods and stateless communication for web service interaction.

Docker

Infrastructure

A platform for developing, shipping, and running applications in isolated containers with consistent environments.

Event-Driven Architecture

Architecture Patterns

An architecture pattern where the flow of the system is determined by events — significant changes in state.

Availability Zone

Infrastructure

An isolated location within a cloud region with independent power, cooling, and networking for high availability.

Multi-Tenancy

Strategy & Economics

A software architecture where a single instance serves multiple customers, with each tenant's data isolated and invisible to others.