Versioning

Pin dated REST and WebSocket API versions so contract changes are explicit and your integration behaves consistently over time.

UDX publishes dated REST and WebSocket contracts. For REST, send a UDX-Version request header with a YYYY-MM-DD value; every response echoes the applied UDX-Version. For WebSocket, select a udx.json.YYYY-MM-DD subprotocol during the HTTP Upgrade; that version remains fixed for the connection.

REST Versioning

Send a version published in the OpenAPI specification:

UDX-Version: <YYYY-MM-DD>

If you omit this header, UDX uses the oldest supported REST version. An integration that omits the header will not adopt a newer contract automatically.

Every response includes the applied UDX-Version. An unsupported value returns 400 and lists the supported versions.

Set UDX-Version explicitly after testing your integration against a contract. Review and test the new OpenAPI contract before changing versions.

WebSocket Versioning

Select a subprotocol published in the AsyncAPI specification when opening the connection:

Sec-WebSocket-Protocol: udx.json.<YYYY-MM-DD>

The selected subprotocol sets the command and message contract for that connection. WebSocket messages do not carry a version header. To change versions, close the connection and reconnect with another supported subprotocol.

Most WebSocket clients accept the subprotocol as a connection option. Use the exact value published in AsyncAPI.