(Visual FoxPro) WebSocket Connect through HTTP Proxy

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

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

LOCAL loRest
LOCAL loSocket
LOCAL lnBTls
LOCAL lnPort
LOCAL lnMaxWaitMs
LOCAL lnSuccess
LOCAL loWs
LOCAL lcResponseBody
LOCAL lnStatusCode

* 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.  
* 

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Rest')
loRest = CreateObject('Chilkat.Rest')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Socket')
loSocket = CreateObject('Chilkat.Socket')

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

* Provide authentication to the HTTP proxy, if needed.
loSocket.HttpProxyUsername = "HTTP_PROXY_LOGIN"
loSocket.HttpProxyPassword = "HTTP_PROXY_PASSWORD"
loSocket.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.
loSocket.HttpProxyForHttp = 1

* Connect to the websocket server through the HTTP proxy.
lnBTls = 0
lnPort = 80
lnMaxWaitMs = 5000
lnSuccess = loSocket.Connect("some-websocket-server.com",lnPort,lnBTls,lnMaxWaitMs)
IF (lnSuccess <> 1) THEN
    ? "Connect Failure Error Code: " + STR(loSocket.ConnectFailReason)
    ? loSocket.LastErrorText
    RELEASE loRest
    RELEASE loSocket
    CANCEL
ENDIF

* Tell the Rest object to use the connected socket.
lnSuccess = loRest.UseConnection(loSocket,1)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loSocket
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.WebSocket')
loWs = CreateObject('Chilkat.WebSocket')

* Tell the WebSocket to use this connection.
lnSuccess = loWs.UseConnection(loRest)
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loRest
    RELEASE loSocket
    RELEASE loWs
    CANCEL
ENDIF

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

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

* Do the open handshake.
lcResponseBody = loRest.FullRequestNoBody("GET","/something")
IF (loRest.LastMethodSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loSocket
    RELEASE loWs
    CANCEL
ENDIF

* 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..)
lnStatusCode = loRest.ResponseStatusCode
? "Response status code: " + STR(lnStatusCode)

IF (lnStatusCode <> 101) THEN
    ? lcResponseBody
    ? "-- Failed because of unexpected response status code."
    RELEASE loRest
    RELEASE loSocket
    RELEASE loWs
    CANCEL
ENDIF

* 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. 
lnSuccess = loWs.ValidateServerHandshake()
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loRest
    RELEASE loSocket
    RELEASE loWs
    CANCEL
ENDIF

? "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...)

? "Success."

RELEASE loRest
RELEASE loSocket
RELEASE loWs