ASGI

rxxxt ships a set of utilities that make it easier to build and compose ASGI applications alongside App.

Transport contexts

• TransportContext exposes the raw ASGI scope, receive and send callables plus helpers for common request metadata.
• HTTPContext builds on TransportContext with helpers such as respond_text, streaming respond_file, and body readers (receive_json, receive_iter, ...).
• WebsocketContext provides setup, receive_message, send_message, and close helpers while tracking the connection state.

Handler decorators

• http_handler wraps a coroutine that receives HTTPContext and filters for HTTP scopes.
• websocket_handler does the same for websocket scopes.
• routed_handler pairs a simple path pattern (using match_path) with a handler and raises ASGINextException so other handlers can try when it does not match.
• http_not_found_handler is a convenience handler that returns a plain 404 response.

These decorators can be used with a Composer instance.

Example: matching /favicon.ico

from rxxxt.asgi import Composer, http_handler, routed_handler, http_not_found_handler

composer = Composer()

@composer.add_handler
@http_handler
@routed_handler("/favicon.ico")
async def favicon(context, params):
  return await context.respond_file("assets/favicon.ico")

composer.add_handler(http_not_found_handler)

If the request path does not match /favicon.ico, routed_handler raises ASGINextException, allowing the next handler in the Composer chain to run.

Composer

Composer is a lightweight middleware pipeline that works using the ASGI protocol:

from rxxxt.asgi import Composer, http_handler, http_not_found_handler

composer = Composer()

@composer.add_handler
@http_handler
def hello(context):
  return context.respond_text("hello")

composer.add_handler(http_not_found_handler)

Handlers that cannot process a scope should raise ASGINextException (or call context.next() on a TransportContext). Composer will call the next handler in the chain. Add http_not_found_handler as a final fallback to send a simple 404 when no HTTP handler matches.

Typing helpers

The aliases ASGIScope, ASGIFnReceive, ASGIFnSend and ASGIHandler mirror the ASGI call signatures so middleware you write here works with uvicorn, Starlette/FastAPI, or any other ASGI-compatible stack.