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WebSocket connection with custom handshake

The WebSocket connection with custom handshake is used when some headers need to initialize the connection.

Note

This use case provides more functionality to generate a customizable handshake. However, it is not possible to reconnect the WebSocket connection.

Tip

See also: WebSocket use cases

WebSocketHandshake configuration

This should be configured in the Connections.Connection.CommunicationOptions.WebSocketHandshake tag. The ID in this tag is the HTTP session of the handshake. With a custom handshake, you need to add a new HTTP session to establish the handshake.

<Connection id="1" name="WebSocket Connection">
   <Http>
   <CommunicationOptions>
      <WebSocket>true</WebSocket>
      <NotifyConnectionPIDs>
         <Connections>7</Connections>
      </NotifyConnectionPIDs>
      <MakeCommandByProtocol>true</MakeCommandByProtocol>
      <WebSocketHandshake>25</WebSocketHandshake>
   </CommunicationOptions>
   <UserSettings>
      <BusAddress>
         <DefaultValue>byPassProxy</DefaultValue>
      </BusAddress>
      <IPport>
         <DefaultValue>8050</DefaultValue>
      </IPport>
      <TimeoutTime>
         <DefaultValue>5000</DefaultValue>
      </TimeoutTime>
   </UserSettings>
   </Http>
</Connection>

HTTP.Session configuration

<Session id="25" name="WebSocket Handshake">
   <Connection id="1">
      <Request verb="GET" pid="8">
         <Headers>
            <Header key="Sec-WebSocket-Extensions" pid="9"></Header>
         </Headers>
      </Request>
      <Response statusCode="220">
         <Content pid="270" />
      </Response>
   </Connection>
</Session>

Parameter 8 contains the default value x-nmos/events/ws. It is possible to make a write parameter on this value and save parameter 8. After a restart, the saved value will be used to establish the WebSocket connection.

<Param id="8" trending="false" save="true">
   <Name>WebsocketUrl</Name>
   <Description>Websocket URL</Description>
   <Type>read</Type>
   <Information>
      <Subtext>This is the last part of the WebSocket connection URL.</Subtext>
   </Information>
   <Interprete>
      <RawType>other</RawType>
      <LengthType>next param</LengthType>
      <Type>string</Type>
      <DefaultValue>x-nmos/events/ws</DefaultValue>
   </Interprete>
   <Display>
      <RTDisplay>true</RTDisplay>
   </Display>
   <Measurement>
      <Type>string</Type>
   </Measurement>
</Param>

For this handshake, an extra header is needed. Add the correct header key and place its value in a parameter. Parameter 9 is used for the header. It has a default value.

<Param id="9" trending="false">
   <Name>Header</Name>
   <Description>Header</Description>
   <Type>read</Type>
   <Interprete>
      <RawType>other</RawType>
      <LengthType>next param</LengthType>
      <Type>string</Type>
      <DefaultValue>permessage-deflate; client_max_window_bits</DefaultValue>
   </Interprete>
</Param>

The response status code and content are not necessary in the Connection tag. Those can be removed if they are not used.

Propose changes