Websocket Spec

Data Access - Query Data via SQL

A WebSocket allows the client to request data using SQL as input.

Use the following URL to open a WebSocket connection. Depending on deployment, use ws (not-secure) or wss (secure) connection:

Once the connection is established, the server expects the client to send a JSON message with the following structure:

The client should wait for incoming messages and stop when EOF is received. The server sends JSON-encoded messages, the payload structure is:

Since there are multiple types of messages the server sends, the type attribute determines the data structure for the data payload. Below is the list of possible type values:

Message types

Heartbeat

The data the attribute is null. The client should ignore these messages.

Error

In this case, the payload structure is:

Stats

When requested the payload format is:

A possible payload can be:

Metadata

The payload format is:

End

The payload format is:

Bad Record

The payload format is:

Sentinel

The payload format is:

Record

Given the type RECORD the payloads contains the data returned to the client, and it is dependent on the SQL input. The payload format is:

Examples

For a topic which contains nested data for both key and value.

The payload format is:

If the Kafka message key is null the response would be:

Projecting the key will not return the key attribute:

produces the following output:

Aggregating data will not return the key and metadata attributes: