Rack

Definitions

1. A Ruby web server interface specification that defines a minimal contract: an application is any object that responds to call(env) and returns a [status, headers, body] triplet. Rack provides the common layer between Ruby web frameworks (Rails, Sinatra) and web servers (Puma, Unicorn), and enables composable middleware stacks for concerns like logging, authentication, and CORS.

   In plain English: A standard adapter between Ruby web applications and web servers, so any Ruby framework can work with any compatible server.

   Example: "We wrote a Rack middleware to inject request tracing headers before the request even hits the Rails router."

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