Xbase++

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.

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Xbase++

LOCAL nSuccess
LOCAL oSocket
LOCAL nBTls
LOCAL nMaxWaitMs
LOCAL nMessageLength

nSuccess := 0

oSocket := CreateObject("Chilkat.Socket")

//  Connect to the server using TLS.
nBTls := 1
nMaxWaitMs := 5000
nSuccess := oSocket:Connect("example.com", 5000, nBTls, nMaxWaitMs)
IF (nSuccess == 0)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

//  Read a four-byte length prefix as a signed 32-bit integer (network byte order by default).  A
//  return value of -1 indicates failure.
nMessageLength := oSocket:ReceiveCount()
IF (nMessageLength < 0)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

? "The peer will send " + Str(nMessageLength) + " bytes."

oSocket:destroy()