SubscriptionTypeGraphQLTransportWS is for subscriptions using a WebSocket connection with 'graphql-transport-ws' as protocol.

SubscriptionTypeGraphQLWS is for subscriptions using a WebSocket connection with 'graphql-ws' as protocol.

SubscriptionTypeSSE is for Server-Sent Events (SSE) subscriptions.

SubscriptionTypeUnknown is for unknown or undefined subscriptions.

FederationEngineConfigFactory is used to create a v2 engine config for a supergraph with multiple data sources for subgraphs.

ProxyEngineConfigFactory is used to create a v2 engine config with a single upstream and a single data source for this upstream.

ProxyUpstreamConfig holds configuration to configure a single data source to a single upstream.