-`subscriptions::serve_graphql_transport_ws()` function allowing to process the [new `graphql-transport-ws` GraphQL over WebSocket Protocol][graphql-transport-ws]. ([#1158])
-`subscriptions::make_ws_filter()` function providing endpoint with auto-selection between the [legacy `graphql-ws` GraphQL over WebSocket Protocol][graphql-ws] and the [new `graphql-transport-ws` GraphQL over WebSocket Protocol][graphql-transport-ws], based on the `Sec-Websocket-Protocol` HTTP header value. ([#1191])
- Made `schema` argument of `make_graphql_filter()` and `make_graphql_filter_sync()` polymorphic, allowing to specify external `Arc`ed `schema`. ([#1136], [#1135])