B4X

Receive a 4-byte Length Prefix from a Socket

Demonstrates Socket.ReceiveCount, which reads a four-byte length prefix as a signed 32-bit integer. A return value of -1 indicates failure.

Background. Reading the length prefix first tells the application exactly how many bytes to read for the message body, which is a reliable way to know when a full message has arrived.

Chilkat B4X Downloads

Download Chilkat for B4X

B4X

Dim success As Boolean = False

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

'  Connect to the server using TLS.
Dim bTls As Boolean = True
Dim maxWaitMs As Int = 5000
success = socket.Connect("example.com", 5000, bTls, maxWaitMs)
If success = False Then
    Log(socket.LastErrorText)
    Return
End If


'  Read a four-byte length prefix as a signed 32-bit integer (network byte order by default).  A
'  return value of -1 indicates failure.
Dim messageLength As Int = socket.ReceiveCount
If messageLength < 0 Then
    Log(socket.LastErrorText)
    Return
End If

Log("The peer will send " & messageLength & " bytes.")