Engine Entry Rules

Engine entries (type: engine) are HTTP implementations that applications are not written against - raw sockets, custom parsers, low-level I/O, built to show what a transport or a technique can do rather than to host application code. They are not frameworks and are ranked separately. (Reverse proxies and static-file servers like nginx and h2o are classified as Infrastructure, not Engine.)

What qualifies as an engine

• Raw TCP socket servers with custom HTTP parsing
• Direct io_uring or epoll implementations
• Application-server hosts, where your code is written against a protocol interface rather than the server's own API - a WSGI or ASGI server, a Rack handler

What does not

A server whose own API is the surface applications are written and deployed on is a framework entry, however thin it is. A runtime's built-in HTTP server - node:http, Deno.serve, Bun.serve, Go's net/http - is a framework entry, and so is a low-level server library that people ship services on directly.

Having no router, no middleware stack and no ecosystem does not make something an engine - see Frameworks.

Rules

• Must implement the endpoint spec correctly
• Must pass the validation suite
• No restrictions on implementation approach, with one exception: on the static profiles, file contents may be served from memory only through the engine's own static file handling, not a cache assembled in the entry, and that cache must follow the disk - replacing a file must change the next response
• Ranked separately from framework entries (flagship and emerging)
• Only participates in connection-level tests (baseline, pipelined, limited-conn) and protocol tests (H2, H3, gRPC, WebSocket) by default