Visual FoxPro

Wait for a Socket to Become Readable

Demonstrates Socket.SelectForReading, which waits for read-ready activity on the socket, or on any contained socket when the object is a socket set. It returns 1 if ready, 0 on timeout, or -1 on error.

Background. A timeoutMs of 0 performs a nonblocking poll. With a socket set, this monitors many connections at once for readability.

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Visual FoxPro

LOCAL lnSuccess
LOCAL loSocket
LOCAL lnBTls
LOCAL lnMaxWaitMs
LOCAL lnReady

lnSuccess = 0

loSocket = CreateObject('Chilkat.Socket')

*  Connect to the server using TLS.
lnBTls = 1
lnMaxWaitMs = 5000
lnSuccess = loSocket.Connect("example.com",5000,lnBTls,lnMaxWaitMs)
IF (lnSuccess = 0) THEN
    ? loSocket.LastErrorText
    RELEASE loSocket
    CANCEL
ENDIF

*  Wait up to 5 seconds for read-ready activity on the socket (or, for a socket set, on any contained
*  socket).  Returns 1 if ready, 0 on timeout, or -1 on error.
lnReady = loSocket.SelectForReading(5000)
IF (lnReady < 0) THEN
    ? loSocket.LastErrorText
    RELEASE loSocket
    CANCEL
ENDIF

IF (lnReady <> 1) THEN
    ? "No data became available before the timeout."
    RELEASE loSocket
    CANCEL
ENDIF

? "The socket has data ready to read."

RELEASE loSocket