B4X

WebSocket Connect

See more WebSocket Examples

Demonstrates how to establish a WebSocket connection. Once the connection is established, messages may be sent back-and-forth. Messages are sent in frames, where the last frame in the message is indicated by a "final" bit. A frame constitutes the entire message if the first frame sent has the "final" bit sent. (In most cases, you'll probably be sending single-frame messages.) B4X

Dim success As Boolean = False

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

'  --------------------------------------------------
'  A WebSocket connection begins life as an HTTP GET request containing a few special header fields,
'  such as "Upgrade: websocket".   

'  Your application will use the Chilkat Rest class to send the initial HTTP GET.  This allows you
'  to use the full capability of the Chilkat Rest class to customize the GET for any particular situation.
'  For example:
'  
'    - If custom HTTP request header fields must be added.
'    - If authentication is required, such as OAuth2, OAuth1, Basic HTTP Auth, etc.
'    - If HTTPS, SSH Tunneling, Proxies (HTTP or SOCKS), or other advanced connection or TLS features are required.
'  

Dim rest As ChilkatRest
rest.Initialize("rest")
success = rest.Connect("someserver.com", 80, False, False)
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-something")
rest.AddHeader("Origin", "http://someserver.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 object...)