Send a 4-byte Length Prefix over a Socket

See more Socket/SSL/TLS Examples

Demonstrates Socket.SendCount, which sends a four-byte length prefix in network byte order. This is typically used to tell the peer how many bytes follow.

llSuccess = .F.

loSocket = createobject("CkSocket")

//  Connect to the server using TLS.
llBTls = .T.
lnMaxWaitMs = 5000
llSuccess = loSocket.Connect("example.com",5000,llBTls,lnMaxWaitMs)
if (llSuccess = .F.) then
    ? loSocket.LastErrorText
    release loSocket
    return
endif

//  Send a four-byte length prefix in network byte order.  A common framing pattern is to send the
//  number of bytes in a message before the message itself, so the peer knows exactly how many bytes
//  to read.
lnMessageLength = 512
llSuccess = loSocket.SendCount(lnMessageLength)
if (llSuccess = .F.) then
    ? loSocket.LastErrorText
    release loSocket
    return
endif

? "Length prefix sent."


release loSocket