PowerBuilder

Send and Receive WebSocket Messages

See more WebSocket Examples

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

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.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Ws
oleobject loo_Rest
string ls_ResponseBodyIgnored
integer li_FinalFrame
integer li_ReceivedFinalFrame
string ls_ReceivedMsg

li_Success = 0

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

loo_Ws = create oleobject
li_rc = loo_Ws.ConnectToNewObject("Chilkat.WebSocket")
if li_rc < 0 then
    destroy loo_Ws
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// 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.

loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")

// 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.
li_Success = loo_Rest.Connect("websockets.chilkat.io",80,0,0)
loo_Ws.UseConnection(loo_Rest)
loo_Ws.AddClientHeaders()
ls_ResponseBodyIgnored = loo_Rest.FullRequestNoBody("GET","/wsChilkatEcho.ashx")
li_Success = loo_Ws.ValidateServerHandshake()
if li_Success <> 1 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// This example demonstrates sending and receiving a multi-frame message.

// The websocket message will be composed of three text lines, each frame will contain a single line.

// Send the 1st frame in the message.
li_FinalFrame = 0
li_Success = loo_Ws.SendFrame("This is the 1st frame~r~n",li_FinalFrame)
if li_Success <> 1 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// Send the 2nd frame in the message.
li_Success = loo_Ws.SendFrame("This is the 2nd frame~r~n",li_FinalFrame)
if li_Success <> 1 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// Send the 3rd and final frame in the message.
li_FinalFrame = 1
li_Success = loo_Ws.SendFrame("This is the 3rd frame~r~n",li_FinalFrame)
if li_Success <> 1 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// 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.
li_ReceivedFinalFrame = 0
do while li_ReceivedFinalFrame = 0

    li_Success = loo_Ws.ReadFrame()
    if li_Success <> 1 then
        Write-Debug "Failed to receive a frame"
        Write-Debug "ReadFrame fail reason = " + string(loo_Ws.ReadFrameFailReason)
        Write-Debug loo_Ws.LastErrorText
        destroy loo_Ws
        destroy loo_Rest
        return
    end if

    li_ReceivedFinalFrame = loo_Ws.FinalFrame

    // Show the opcode and final frame bit for the frame just received:
    Write-Debug "Frame opcode: " + loo_Ws.FrameOpcode
    Write-Debug "Final frame: " + string(li_ReceivedFinalFrame)
loop

// Return the message accumulated in the above calls to ReadFrame.
ls_ReceivedMsg = loo_Ws.GetFrameData()
Write-Debug "Received: " + ls_ReceivedMsg

// Close the websocket connection.
li_Success = loo_Ws.SendClose(1,1000,"Closing this websocket.")
if li_Success <> 1 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// Read the Close response.
li_Success = loo_Ws.ReadFrame()
if li_Success <> 1 then
    Write-Debug "ReadFrame fail reason = " + string(loo_Ws.ReadFrameFailReason)
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Ws
    destroy loo_Rest
    return
end if

// Should receive the "Close" opcode.
Write-Debug "Received opcode: " + loo_Ws.FrameOpcode
// Should be the same status code we sent (1000)
Write-Debug "Received close status code: " + string(loo_Ws.CloseStatusCode)
// The server may echo the close reason.  If not, this will be empty.
Write-Debug "Echoed close reason: " + loo_Ws.CloseReason

Write-Debug "Success."


destroy loo_Ws
destroy loo_Rest