Visual FoxPro

Poll a Socket for Available Data

Demonstrates Socket.PollDataAvailable, which performs a nonblocking check for readable activity and returns whether data or another read-ready condition is present.

Background. This lets an application check for incoming data without blocking, for example in an event loop that services multiple tasks.

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Visual FoxPro

LOCAL lnSuccess
LOCAL loSocket
LOCAL lnBTls
LOCAL lnMaxWaitMs
LOCAL lnBAvailable

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

*  Perform a nonblocking check for readable data.  Returns 1 when data or another read-ready
*  condition is present, and 0 when nothing is immediately available.
lnBAvailable = loSocket.PollDataAvailable()
IF (lnBAvailable <> 1) THEN
    ? "No data is immediately available."
ELSE
    ? "Data is available to read."
ENDIF

RELEASE loSocket