Visual FoxPro

Cancel HTTP Get Async Task if not Completed after a Max Time

See more HTTP Examples

Demonstrates how to wait a maximum amount of time for an asynchronous task to completed. If not completed in the allotted amount of time, the task is cancelled. Visual FoxPro

LOCAL lnSuccess
LOCAL loHttp
LOCAL lcUrl
LOCAL loTask
LOCAL lnWaitMaxMs
LOCAL lnWasCanceled
LOCAL lcResponseStr

lnSuccess = 0

* This example requires the Chilkat API to have been previously unlocked.
* See Global Unlock Sample for sample code.

loHttp = CreateObject('Chilkat.Http')

* Set some timeouts, in seconds:
loHttp.ConnectTimeout = 15
* ReadTimeout specifies the max number of seconds that must elapse when no additional data is received before
* timing out.  For example, if a server sends a 300 byte response at the rate of 1 byte per second, then
* ReadTimeout would never cause a timeout because there is never a 15 second interval when nothing arrives.
loHttp.ReadTimeout = 15

lcUrl = "https://your-url.com/something"
loTask = loHttp.QuickGetStrAsync(lcUrl)
loTask.Run()

* Wait a maximum of waitMaxMs for the task (i.e. the HTTP GET) to complete.
* The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
lnWaitMaxMs = 20000
loTask.Wait(lnWaitMaxMs)

* At this point, the GET may or may not have completed.  
* Rather than checking the Task status, we can call task.Cancel because
* if the Task is no longer running (because it already completed, was canceled or aborted), then the 
* call to Cancel is a NO-OP (meaning it does nothing and the Task's status is unaffected).
* Also, task.Cancel returns 1 if the task was in the "queued" or "running" state and was canceled or aborted. 
* The method returns 0 if the task has any other status.
lnWasCanceled = loTask.Cancel()
IF (lnWasCanceled = 1) THEN
    ? "The HTTP GET took too long and was canceled."
ELSE
    * Find out what happened.
    IF (loTask.StatusInt = 7) THEN
        * The task completed, which means the background thread's call to QuickGetStr completed
        * with success or failure.  Find out which...
        IF (loTask.TaskSuccess = 1) THEN
            * Get the string response for the call to QuickGetStr (which happened in Chilkat's background thread).
            lcResponseStr = loTask.GetResultString()
            ? lcResponseStr
            ? "HTTP GET successful!"
        ELSE
            ? "HTTP GET failed prior to waitMaxMs..."
            ? loTask.ResultErrorText
        ENDIF

    ELSE
        * The task must've been canceled or aborted by some other means..
        ? "Task did not complete.  Final status: " + loTask.Status
    ENDIF

ENDIF

RELEASE loTask

RELEASE loHttp