(Lianja) 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 Lianja Extension Download Chilkat Lianja Extension

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

loRest = createobject("CkRest")

// Connect to the Amazon AWS REST server.
llBTls = .T.
lnPort = 443
llBAutoReconnect = .T.
llSuccess = loRest.Connect("s3.amazonaws.com",lnPort,llBTls,llBAutoReconnect)

// ----------------------------------------------------------------------------
// 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.
loAuthAws = createobject("CkAuthAws")
loAuthAws.AccessKey = "AWS_ACCESS_KEY"
loAuthAws.SecretKey = "AWS_SECRET_KEY"
loAuthAws.ServiceName = "s3"
llSuccess = 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.
llSuccess = loRest.SendReqNoBody("GET","/starfish.jpg")
if (llSuccess <> .T.) then
    ? loRest.LastErrorText
    release loRest
    release loAuthAws
    return
endif

// Read the response header.
lnResponseStatusCode = loRest.ReadResponseHeader()
if (lnResponseStatusCode < 0) then
    ? loRest.LastErrorText
    release loRest
    release loAuthAws
    return
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 <> .T.) then
        ? loRest.LastErrorText
    else
        ? lcErrResponse
    endif

    release loRest
    release loAuthAws
    return
endif

loBodyStream = createobject("CkStream")
// 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,.T.)

// Start the task. 
llSuccess = loReadResponseBodyTask.Run()

// The application can now read the bodyStream...
do while (loBodyStream.EndOfStream <> .T.)

    // 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 <> .T.) then
        ? "Failed to receive more response data."
        // Make sure the background task is aborted/cancelled.
        llSuccess = loReadResponseBodyTask.Cancel()
        release loReadResponseBodyTask
        release loRest
        release loAuthAws
        release loBodyStream
        return
    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