(SQL Server) Send a WebSocket Ping Control Frame

Ping and Pong messages are the heartbeat of websockets. See Pings and Pongs

"At any point after the handshake, either the client or the server can choose to send a ping to the other party. When the ping is received, the recipient must send back a pong as soon as possible. You can use this to make sure that the client is still connected, for example. A ping or pong is just a regular frame, but it's a control frame. Pings have an opcode of 0x9, and pongs have an opcode of 0xA. When you get a ping, send back a pong with the exact same Payload Data as the ping (for pings and pongs, the max payload length is 125). You might also get a pong without ever sending a ping; ignore this if it happens."

This example demonstrates how to send a Ping in the midst of sending a message.

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @ws int
    -- Use "Chilkat_9_5_0.WebSocket" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.WebSocket', @ws OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- The PongAutoConsume property is 1 by default.  This means that any Pong frames that are received 
    -- will automatically be consumed, and the ReadFrame method will continue reading the next incoming frame before it returns.
    EXEC sp_OASetProperty @ws, 'PongAutoConsume', 1

    -- For brevity, this example does not check for errors when etablishing the WebSocket connection.
    -- See Establish WebSocket Connection for more complete sample code for making the connection.

    DECLARE @rest int
    -- Use "Chilkat_9_5_0.Rest" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Rest', @rest OUT

    -- Connect to websockets.chilkat.io
    -- IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
    -- IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
    -- ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
    DECLARE @success int
    EXEC sp_OAMethod @rest, 'Connect', @success OUT, 'websockets.chilkat.io', 80, 0, 0
    EXEC sp_OAMethod @ws, 'UseConnection', @success OUT, @rest
    EXEC sp_OAMethod @ws, 'AddClientHeaders', @success OUT
    DECLARE @responseBodyIgnored nvarchar(4000)
    EXEC sp_OAMethod @rest, 'FullRequestNoBody', @responseBodyIgnored OUT, 'GET', '/wsChilkatEcho.ashx'
    EXEC sp_OAMethod @ws, 'ValidateServerHandshake', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- This example sends a multi-frame message to the Chilkat echo server, and reads the response.
    -- In the midst of sending the message, we'll send a Ping control frame.  The server should respond with a Pong frame,
    -- and we'll automatically consume it.

    -- Send the 1st frame in the message.
    DECLARE @finalFrame int
    SELECT @finalFrame = 0
    EXEC sp_OAMethod @ws, 'SendFrame', @success OUT, 'This is the 1st frame' + CHAR(13) + CHAR(10), @finalFrame
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Let's send a Ping frame here...
    EXEC sp_OAMethod @ws, 'SendPing', @success OUT, 'This is a ping'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Send the 2nd frame in the message.
    EXEC sp_OAMethod @ws, 'SendFrame', @success OUT, 'This is the 2nd frame' + CHAR(13) + CHAR(10), @finalFrame
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Send the 3rd and final frame in the message.
    SELECT @finalFrame = 1
    EXEC sp_OAMethod @ws, 'SendFrame', @success OUT, 'This is the 3rd and final frame' + CHAR(13) + CHAR(10), @finalFrame
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Read an incoming frames until we receive the final frame.
    -- Note: It may be that the echo server (websockets.chilkat.io) responds with 
    -- the full message in a single final frame.
    -- 
    -- The Pong response will be consumed automatically because the PongAutoConsume property is 1.
    -- Therefore, we don't need to worry about handling an incoming Pong.
    DECLARE @receivedFinalFrame int
    SELECT @receivedFinalFrame = 0
    WHILE @receivedFinalFrame = 0
      BEGIN

        EXEC sp_OAMethod @ws, 'ReadFrame', @success OUT
        IF @success <> 1
          BEGIN

            PRINT 'Failed to receive a frame'

            EXEC sp_OAGetProperty @ws, 'ReadFrameFailReason', @iTmp0 OUT
            PRINT 'ReadFrame fail reason = ' + @iTmp0
            EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @ws
            EXEC @hr = sp_OADestroy @rest
            RETURN
          END

        EXEC sp_OAGetProperty @ws, 'FinalFrame', @receivedFinalFrame OUT

        -- Show the opcode and final frame bit for the frame just received:

        EXEC sp_OAGetProperty @ws, 'FrameOpcode', @sTmp0 OUT
        PRINT 'Frame opcode: ' + @sTmp0

        PRINT 'Final frame: ' + @receivedFinalFrame

        PRINT '--'
      END

    -- Return the message accumulated in the above calls to ReadFrame.
    DECLARE @receivedMsg nvarchar(4000)
    EXEC sp_OAMethod @ws, 'GetFrameData', @receivedMsg OUT

    PRINT 'Received: ' + @receivedMsg

    -- Close the websocket connection.
    EXEC sp_OAMethod @ws, 'SendClose', @success OUT, 1, 1000, 'Closing this websocket.'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Read the Close response.
    EXEC sp_OAMethod @ws, 'ReadFrame', @success OUT
    IF @success <> 1
      BEGIN

        EXEC sp_OAGetProperty @ws, 'ReadFrameFailReason', @iTmp0 OUT
        PRINT 'ReadFrame fail reason = ' + @iTmp0
        EXEC sp_OAGetProperty @ws, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ws
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Should receive the "Close" opcode.

    EXEC sp_OAGetProperty @ws, 'FrameOpcode', @sTmp0 OUT
    PRINT 'Received opcode: ' + @sTmp0
    -- Should be the same status code we sent (1000)

    EXEC sp_OAGetProperty @ws, 'CloseStatusCode', @iTmp0 OUT
    PRINT 'Received close status code: ' + @iTmp0
    -- The server may echo the close reason.  If not, this will be empty.

    EXEC sp_OAGetProperty @ws, 'CloseReason', @sTmp0 OUT
    PRINT 'Echoed close reason: ' + @sTmp0


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @ws
    EXEC @hr = sp_OADestroy @rest


END
GO