The available WebSocket subprotocols are:-
  • auto: This is the default subprotocol. If auto is selected, we negotiate with the subgraph for the subprotocol. The subprotocols graphql-ws and graphql-transport-ws are used for the negotiation. If the subgraph doesn’t return a subprotocol, it falls back to graphql-ws.
  • graphql-ws
  • graphql-transport-ws

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How to set the WebSocket subprotocol

  • While creating a subgraph, the WebSocket subprotocol can be set using the create subgraph command.
npx wgc subgraph create <name> -r <routing-url> --label [labels] --subscription-protocol ws --websocket-subprotocol <subprotocol>
  • If the subgraph is already created, it can be updated using the update subgraph command.
npx wgc subgraph update <name> --websocket-subprotocol <protocol>

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Configure Subscriptions for local development

When composing a Graph locally, you can supply the subprotocol using the following configuration. 
version: 1
subgraphs:
  - name: employees
    routing_url: "http://localhost:4001/graphql"
    subscription:
      protocol: "ws"
      websocketSubprotocol: "graphql-ws"

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WebSocket Authentication

Cosmo Router supports WebSocket authentication and offers two configurable options for handling it
  • via Headers
  • via Initial Payload

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Default WebSocket Authentication behaviour

By default, the Router expects the JWT (JSON Web Token) to be included in the request headers. This token is then used to authenticate the WebSocket connection. If the Router makes subsequent Subgraph requests via HTTP(S), the header can be forwarded to the Subgraphs.

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WebSocket Authentication via initial payload

Some clients, e.g. browsers, cannot set Headers when initiating a WebSocket connection. As such, the default behaviour to authenticate via Authorization Header is not suitable. For such cases, you can configure the Router to accept clients to Authenticate using the initial payload when initiating a WebSocket connection. When enabled, a client can set up a WebSocket connection and then send a JWT as part of the initial WebSocket message using the initial_payloadfield. In addition to allowing clients to authenticate using this method, you can also enable the export_tokenoption. This feature takes the token from the initial payload and exports it into the Header of the Upgrade request. This allows the Router to treat every Subscription from this client as if the client sent the token as a header. Consequently, if header forwarding rules are enabled, the exported token will be forwarded accordingly. 
# config.yaml

websocket:
  enabled: true
  authentication:
    from_initial_payload:
      enabled: true
      key: "Authorization" # The property name in the initial payload holding the JWT. Default is 'Authorization'.
      export_token:
        enabled: true
        header_key: "Authorization" # Header key for exporting the JWT to the request header. If different from 'Authorization', include it in 'forward_upgrade_headers'.
  forward_upgrade_headers: # Forward upgrade request headers in the extensions payload when starting a subscription on a Subgraph.
    enabled: true
    allow_list: ["Authorization"] # Headers to forward when initiating a subscription on a subgraph. Default is 'Authorization'.