LESSON 188 / 215·2 min readIntermediate

FastAPI

ReferenceReference guide

Words made simple

A few useful meanings before you read the explanation.

FastAPI: A Python framework for building APIs, often used with typed request and response data.
LLM: A model trained to work with language. It can write or summarize text, but its answer still needs checking against reliable information.
Schema: A description of the fields and value types that data should contain. It helps check that an answer has the expected shape.

More words from this lesson

Durable: Able to retain progress and recover across interruptions. Durable workflows require appropriate storage and retry behavior.
Authentication: Checking who a user or service is, such as by verifying a login session.
HTTP: The request-and-response protocol used on the web. HTTPS adds encryption to protect information in transit.
SDK: A set of code tools provided to help an application use a service or framework.
Dependency: A library or package that your application relies on. Compatible versions help the application run as expected.

It provides a Python HTTP service boundary with declared routes and data schemas.
Pydantic validates input/output, while application dependencies and services enforce identity, permissions, and business rules.

In bounded workers with durable jobs, retries, status, and resource isolation.
FastAPI can start/check tasks or expose fast specialized operations; it should not keep arbitrary multi-minute processing alive solely through an open request.

Only for a concrete Python library, local model, numerical workload, or scaling boundary.
Otherwise another service adds authentication, deployments, networking, contracts, and failures without meaningful benefit.

PAUSE & RECALL