markethub-ddn 1.0.0
MarketHub DDN - WebSocket SDK for Centrifugo with built-in offset persistence and automatic recovery
Requires Python: >=3.9
Keywords: Centrifugo, DDN, MarketHub, Offset Persistence, Pub/Sub, Realtime, Streaming, WebSocket

# centrifuge-python

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This is a WebSocket real-time SDK for [Centrifugo](https://github.com/centrifugal/centrifugo) server (and any [Centrifuge-based](https://github.com/centrifugal/centrifuge) server) on top of Python asyncio library.

> [!TIP]
> If you are looking for Centrifugo [server API](https://centrifugal.dev/docs/server/server_api) client – check out [pycent](https://github.com/centrifugal/pycent) instead.

Before starting to work with this library check out Centrifugo [client SDK API specification](https://centrifugal.dev/docs/transports/client_api) as it contains common information about Centrifugal real-time SDK behavior. This SDK supports all major features of Centrifugo client protocol - see [SDK feature matrix](https://centrifugal.dev/docs/transports/client_sdk#sdk-feature-matrix).

## Install

```
pip install centrifuge-python
```

Then in your code:

```
from centrifuge import Client
```

See [example code](https://github.com/centrifugal/centrifuge-python/blob/master/example.py) and [how to run it](#run-example) locally.

## JSON vs Protobuf protocols

By default, SDK uses JSON protocol. If you want to use Protobuf protocol instead then pass `use_protobuf=True` option to `Client` constructor.

When using JSON protocol:

* all payloads (data to publish, connect/subscribe data) you pass to the library are encoded to JSON internally using `json.dumps` before sending to server. So make sure you pass only JSON-serializable data to the library.
* all payloads received from server are decoded to Python objects using `json.loads` internally before passing to your code.

When using Protobuf protocol:

* all payloads you pass to the library must be `bytes` or `None` if optional. If you pass non-`bytes` data – exception will be raised.
* all payloads received from the library will be `bytes` or `None` if not present.
* don't forget that when using Protobuf protocol you can still have JSON payloads - just encode them to `bytes` before passing to the library.

## Callbacks should not block

Event callbacks are called by SDK using `await` internally, the websocket connection read loop is blocked for the time SDK waits for the callback to be executed. This means that if you need to perform long operations in callbacks consider moving the work to a separate coroutine/task to return fast and continue reading data from the websocket.

The fact WebSocket read is blocked for the time we execute callbacks means that you can not call awaitable SDK APIs from callback – because SDK does not have a chance to read the reply. You will get `OperationTimeoutError` exception. The rule is the same - do the work asynchronously, for example use `asyncio.ensure_future`.

## Run example

To run [example](https://github.com/centrifugal/centrifuge-python/blob/master/example.py), first start Centrifugo with config like this:

```json
{
  "client": {
    "token": {
      "hmac_secret_key": "secret"
    }
  },
  "channel": {
    "namespaces": [
      {
        "name": "example",
        "presence": true,
        "history_size": 300,
        "history_ttl": "300s",
        "join_leave": true,
        "force_push_join_leave": true,
        "allow_publish_for_subscriber": true,
        "allow_presence_for_subscriber": true,
        "allow_history_for_subscriber": true
      }
    ]
  }
}
```

And then:

```bash
python -m venv env
. env/bin/activate
make dev
python example.py
```

## Run tests

To run tests, first start Centrifugo server:

```bash
docker pull centrifugo/centrifugo:v6
docker run -d -p 8000:8000 \
-e CENTRIFUGO_CLIENT_TOKEN_HMAC_SECRET_KEY="secret" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_ALLOWED_DELTA_TYPES="fossil" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_DELTA_PUBLISH="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_PRESENCE="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_JOIN_LEAVE="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_FORCE_PUSH_JOIN_LEAVE="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_HISTORY_SIZE="100" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_HISTORY_TTL="300s" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_FORCE_RECOVERY="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_ALLOW_PUBLISH_FOR_SUBSCRIBER="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_ALLOW_PRESENCE_FOR_SUBSCRIBER="true" \
-e CENTRIFUGO_CHANNEL_WITHOUT_NAMESPACE_ALLOW_HISTORY_FOR_SUBSCRIBER="true" \
-e CENTRIFUGO_CLIENT_SUBSCRIBE_TO_USER_PERSONAL_CHANNEL_ENABLED="true" \
-e CENTRIFUGO_LOG_LEVEL="trace" \
centrifugo/centrifugo:v6 centrifugo
```

And then (from cloned repo root):

```bash
python -m venv env
. env/bin/activate
make dev
make test
```