B4X

WebSocket Connect through HTTP Proxy

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an HTTP proxy server. B4X

Dim success As Boolean = False

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

'  --------------------------------------------------
'  This example borrows the code from the REST using HTTP Proxy example.
'  We first use the Chilkat Socket object to establish a connection to the WebSocket server through an HTTP proxy.
'  Next, the Rest object uses the Socket object for its connection.
'  Finally, the WebSocket object uses the Rest object for its connection.  
'  

Dim rest As ChilkatRest
rest.Initialize("rest")
Dim socket As ChilkatSocket
socket.Initialize("socket")

'  Set the HTTP proxy domain or IP address, and port.
socket.HttpProxyHostname = "192.168.1.79"
socket.HttpProxyPort = 808

'  Provide authentication to the HTTP proxy, if needed.
socket.HttpProxyUsername = "HTTP_PROXY_LOGIN"
socket.HttpProxyPassword = "HTTP_PROXY_PASSWORD"
socket.HttpProxyAuthMethod = "Basic"

'  Indicate that HTTP requests (i.e. the WebSocket opening handshake) will be sent over the socket.
'  This is important for how the HTTP proxy connection is established.
socket.HttpProxyForHttp = True

'  Connect to the websocket server through the HTTP proxy.
Dim bTls As Boolean = False
Dim port As Int = 80
Dim maxWaitMs As Int = 5000
success = socket.Connect("some-websocket-server.com", port, bTls, maxWaitMs)
If success <> True Then
    Log("Connect Failure Error Code: " & socket.ConnectFailReason)
    Log(socket.LastErrorText)
    Return
End If


'  Tell the Rest object to use the connected socket.
success = rest.UseConnection(socket, True)
If success <> True Then
    Log(rest.LastErrorText)
    Return
End If


Dim ws As ChilkatWebSocket
ws.Initialize("ws")

'  Tell the WebSocket to use this connection.
success = ws.UseConnection(rest)
If success <> True Then
    Log(ws.LastErrorText)
    Return
End If


'  Add the standard WebSocket open handshake headers that will be needed.
'  (This adds the required HTTP request headers to the rest object.)
ws.AddClientHeaders

'  Add any additional headers that might be desired.
'  Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
rest.AddHeader("Sec-WebSocket-Protocol", "x-some-websocket-subprotocol")
rest.AddHeader("Origin", "http://some-websocket-server.com")

'  Do the open handshake.
Dim responseBody As String = rest.FullRequestNoBody("GET", "/something")
If rest.LastMethodSuccess <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  If successful, the HTTP response status code should be 101,
'  and the response body will be empty. (If it failed, we'll have a look
'  at the response body..)
Dim statusCode As Int = rest.ResponseStatusCode
Log("Response status code: " & statusCode)

If statusCode <> 101 Then
    Log(responseBody)
    Log("-- Failed because of unexpected response status code.")
    Return
End If


'  We have the expected 101 response, so let's now validate the 
'  contents of the response, such as the value sent by the server in the
'  Sec-WebSocket-Accept header. 
success = ws.ValidateServerHandshake
If success <> True Then
    Log(ws.LastErrorText)
    Return
End If


Log("WebSocket connection successful.")

'  The application may now begin sending and receiving frames on the WebSocket connection.
'  (At this point, we're done with the rest and socket objects...)

Log("Success.")