VBScript

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 VBScript Downloads

Download Chilkat for VBScript

VBScript

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

set socket = CreateObject("Chilkat.Socket")

'  Connect to the server using TLS.
bTls = 1
maxWaitMs = 5000
success = socket.Connect("example.com",5000,bTls,maxWaitMs)
If (success = 0) Then
    outFile.WriteLine(socket.LastErrorText)
    WScript.Quit
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.
messageLength = socket.ReceiveCount()
If (messageLength < 0) Then
    outFile.WriteLine(socket.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("The peer will send " & messageLength & " bytes.")

outFile.Close