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https://github.com/noteable-io/asyncapi-eventrouter

Python framework for AsyncAPI-documented Websocket, PubSub, and other async constructs
https://github.com/noteable-io/asyncapi-eventrouter

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Python framework for AsyncAPI-documented Websocket, PubSub, and other async constructs

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README

          

# asyncapi-eventrouter

*Work in Progress*

Write Python code for Event-Driven Architectures! The **`asyncapi-eventrouter`** prototype library creates Websocket,
PubSub, and other asynchronous frameworks with message validation and automatic schema documentation in the
[AsyncAPI](https://www.asyncapi.com/) specification. It's heavily inspired by how
[FastAPI](https://fastapi.tiangolo.com/) documents REST endpoints in the [OpenAPI](https://swagger.io/specification/)
specification.

## Example

What would the [Streetlights API](https://www.asyncapi.com/docs/tutorials/streetlights#creating-the-asyncapi-file) look like in Python code with `asyncapi-eventrouter`?

```python
# asyncapi.py
from pydantic import BaseModel, Field
from datetime import datetime
from asyncapi_eventrouter import Application

asyncapi_app = Application()

class LightMeasured(BaseModel):
id: int = Field(..., gte=0, description="ID of the streetlight.")
lumens: int = Field(..., gte=0, description="Light intensity measured in lumens.")
sentAt: datetime = Field(..., description="Date and time when the message was sent.")

@asyncapi_app.subscribe(channel_name="light/measured",
event_name="LightMeasured")
async def record_measurement(measurement: LightMeasured):
# record to db or take some other action
return {'received': datetime.now()}
```

```python
# main.py
from fastapi import FastAPI, WebSocket
from asyncapi import asyncapi_app

app = FastAPI()

@app.websocket('/ws')
async def ws(websocket: Websocket):
await ws.accept()
while True:
content = await websocket.receive_text()
response = await asyncapi_app.process(content)
await websocket.send_json(response)

@app.get('/ws-schema')
async def ws_schema():
return asyncapi_app.schema()
```

```python
# client.py
import asyncio
import json
from datetime import datetime

import websockets

async def send_measurement():
data = {"id": 123, "lumens": 42, "sentAt": datetime.now().isoformat()}
event = {"channel": "light/measured", "event": "LightMeasured", "data": data}
async with websockets.connect("ws://localhost:8000/ws") as ws:
await ws.send(json.dumps(event))

if __name__ == '__main__':
asyncio.run(send_measurement())
```

Last but not least, you can view the spec by visiting that `/ws-schema` endpoint or by importing the `asyncapi_app` and dumping the schema.

```python
from asyncapi import asyncapi_app
import yaml

print(yaml.dump(asyncapi_app.schema())

asyncapi: 2.2.0
channels:
light/measured:
publish:
LightMeasured:
payload:
properties:
id:
description: ID of the streetlight.
gte: 0
title: Id
type: integer
lumens:
description: Light intensity measured in lumens.
gte: 0
title: Lumens
type: integer
sentAt:
description: Date and time when the message was sent.
format: date-time
title: Sentat
type: string
required:
- id
- lumens
- sentAt
title: LightMeasured
type: object
```

## Development

This project uses [poetry](https://python-poetry.org/) and [pre-commit](https://pre-commit.com/) for development.

1. `poetry env use 3.9` will create a `.venv` directory in your `asyncapi-eventrouter` directory.
2. `poetry install` will install `asyncapi-eventrouter` and all dependencies into that virtual environment.
3. `pre-commit run --all-files` will show you what will be executed any time you `git commit`.

### Skip Pre-commit

If the `pre-commit` hooks can not be easily resolved, you can still commit using `git commit --no-verify`.

### Testing

This project uses [tox](https://github.com/tox-dev/tox) and [pytest](https://docs.pytest.org) for testing. You'll need to have [installed tox](https://tox.wiki/en/latest/install.html) on your system Python. To run tests, just execute `tox` (`tox -q` for less verbosity, `tox -p` to run in parallel).

You'll also need a system installation for each Python version you want to test with `tox` (e.g. `python3.7`, `python3.8`, `python3.9`, `python3.10`). Installation steps may be different for each OS. On Ubuntu 20.04, it is a matter of adding the [deadsnakes](https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa) repository (`sudo add-apt-repository ppa:deadsnakes/ppa`) and installing the version you want: `sudo apt install python3.10`.

## Inspiration and gratitude

The useful FastAPI project inspires this project. Any code snippets from FastAPI are given credit and attribution in the
source code. We are thankful to the FastAPI community for their work.