(Visual FoxPro) REST Read Response with Stream API

Demonstrates how to make a REST call that returns a binary body, and to receive the body through a stream API.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loRest
LOCAL lnBTls
LOCAL lnPort
LOCAL lnBAutoReconnect
LOCAL lnSuccess
LOCAL loAuthAws
LOCAL lnResponseStatusCode
LOCAL lcErrResponse
LOCAL loBodyStream
LOCAL loReadResponseBodyTask
LOCAL loNextChunk

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Rest')
loRest = CreateObject('Chilkat.Rest')

* Connect to the Amazon AWS REST server.
lnBTls = 1
lnPort = 443
lnBAutoReconnect = 1
lnSuccess = loRest.Connect("s3.amazonaws.com",lnPort,lnBTls,lnBAutoReconnect)

* ----------------------------------------------------------------------------
* Important: For buckets created in regions outside us-east-1,
* there are three important changes that need to be made.
* See Working with S3 Buckets in Non-us-east-1 Regions for the details.
* ----------------------------------------------------------------------------

* Provide AWS credentials for the REST call.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.AuthAws')
loAuthAws = CreateObject('Chilkat.AuthAws')
loAuthAws.AccessKey = "AWS_ACCESS_KEY"
loAuthAws.SecretKey = "AWS_SECRET_KEY"
loAuthAws.ServiceName = "s3"
lnSuccess = loRest.SetAuthAws(loAuthAws)

* Set the bucket name via the HOST header.
* In this case, the bucket name is "chilkat100".
loRest.Host = "chilkat100.s3.amazonaws.com"

* Send the request to download the JPG.
lnSuccess = loRest.SendReqNoBody("GET","/starfish.jpg")
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loAuthAws
    CANCEL
ENDIF

* Read the response header.
lnResponseStatusCode = loRest.ReadResponseHeader()
IF (lnResponseStatusCode < 0) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loAuthAws
    CANCEL
ENDIF

? "Response status code = " + STR(lnResponseStatusCode)

* We expect a 200 response status if the JPG data is coming.
* Otherwise, we'll get a string response body with an error message(or no response body).
IF (lnResponseStatusCode <> 200) THEN
    lcErrResponse = loRest.ReadRespBodyString()
    IF (loRest.LastMethodSuccess <> 1) THEN
        ? loRest.LastErrorText
    ELSE
        ? lcErrResponse
    ENDIF

    RELEASE loRest
    RELEASE loAuthAws
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Stream')
loBodyStream = CreateObject('Chilkat.Stream')
* Set a 10 second read timeout for the stream. 
* (Give up if no data arrives within 10 seconds after calling a read method.)
loBodyStream.ReadTimeoutMs = 10000

* Create a background thread task to read the response body (which feeds
* it to the bodyStream object.)
loReadResponseBodyTask = loRest.ReadRespBodyStreamAsync(loBodyStream,1)

* Start the task. 
lnSuccess = loReadResponseBodyTask.Run()

* The application can now read the bodyStream...
DO WHILE (loBodyStream.EndOfStream <> 1)

    * Read the next chunk of bytes (whatever is immediately available,
    * or wait for more data (up to 10 seconds because we set the stream's ReadTimeoutMs property)
    loNextChunk = loBodyStream.ReadBytes()
    IF (loBodyStream.LastMethodSuccess <> 1) THEN
        ? "Failed to receive more response data."
        * Make sure the background task is aborted/cancelled.
        lnSuccess = loReadResponseBodyTask.Cancel()
        RELEASE loReadResponseBodyTask
        RELEASE loRest
        RELEASE loAuthAws
        RELEASE loBodyStream
        CANCEL
    ENDIF

    * OK.. the app has the next chunk of the body, and may do whatever it wishes with it...
ENDDO

RELEASE loReadResponseBodyTask

? "Successfully received the entire response body."

RELEASE loRest
RELEASE loAuthAws
RELEASE loBodyStream