llsd-asgi

llsd-asgi adds automatic LLSD content negotiation to ASGI applications (Starlette, FastAPI, Quart, etc.) with a single line of code:

app.add_middleware(LLSDMiddleware)

The code for llsd-asgi is based on msgpack-asgi, a similar middleware library for the MessagePack binary format.

Installation

Install with pip:

pip install llsd-asgi

Quickstart (FastAPI)

You can use llsd-asgi with FastAPI like so:

from fastapi import FastAPI
from llsd_asgi import LLSDMiddleware

app = FastAPI()
app.add_middleware(LLSDMiddleware)

Quickstart (Starlette)

As a lower level example using Starlette:

from llsd_asgi import LLSDMiddleware
from starlette.applications import Starlette
from starlette.responses import JSONResponse
from starlette.routing import Route


async def homepage(request):
    return JSONResponse({"hello": "world"})


app = Starlette(debug=True, routes=[
    Route('/', homepage),
])

# Wrap your application with the LLSD middleware
app = LLSDMiddleware(app)

How it works

flowchart TD
    A(Client) <-->|LLSD| B(LLSDMiddleware)
    B <-->|JSON| C(App)

Your ASGI application is wrapped around the LLSDMiddleware, which performs content negotiation based on Content-Type and Accept HTTP headers.

Quirks mode

Passing quirks=True to the middleware enables 🤪 quirks mode. The behavior of this mode matches that of poorly behaved Linden Lab services, where the server returns LLSD even if the client has not requested it.