WebSocket is an API that enables streaming communication between clients and servers. It is a common choice for real-time web applications. Arroyo provides a WebSocket source that allows you to read from WebSocket APIs in your pipeline. WebSocket is a very flexible protocol, and does not have standard semantics for tracking progress or restarting from a past point in time. As a result, the WebSocket source may currently miss messages on recovery. Various APIs may also require some level of negotiation before the WebSocket connection becomes active. The WebSocket source currently supports sending a single subscription message on connection, which is sufficient to work with many real-world APIs. If you’d like to use the WebSocket source with an API that requires additional features, reach out to the team on Discord.

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Configuring the Connection

Websocket sources can be created via the Web UI or directly in SQL. WebSocket creation flow A WebSocket source has several required and optional fields:
FieldDescriptionRequiredExample
endpointThe endpoint for the WebSocket serverYeswss://api.example.com/v1/events
subscription_messageA message that will be sent to the server after connectionNo{"type": "subscribe", "channel": "events"}
For example, in SQL: 
CREATE TABLE coinbase (
    type TEXT,
    price TEXT
) WITH (
    connector = 'websocket',
    endpoint = 'wss://ws-feed.exchange.coinbase.com',
    subscription_message = '{
      "type": "subscribe",
      "product_ids": [
        "BTC-USD"
      ],
      "channels": ["ticker"]
    }',
    format = 'json'
);