PHP Extension

S3 Resume Download

See more Amazon S3 (new) Examples

Suppose an S3 download of a very large file failed for some reason and you have a partial file on disk. Rather than restart the entire download, you wish to download the remaining portion. This example demonstrates how to finish a previously failed download.

Note: This example requires Chilkat v9.5.0.83 or above.

PHP Extension

<?php

include("chilkat.php");

$success = false;

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

$rest = new CkRest();

// Connect to the Amazon AWS REST server.
$bTls = true;
$port = 443;
$bAutoReconnect = true;
$success = $rest->Connect('s3.amazonaws.com',$port,$bTls,$bAutoReconnect);

// ---------------------------------------------------------------------------
// 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.
$authAws = new CkAuthAws();
$authAws->put_AccessKey('AWS_ACCESS_KEY');
$authAws->put_SecretKey('AWS_SECRET_KEY');
$authAws->put_ServiceName('s3');
$success = $rest->SetAuthAws($authAws);

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
$rest->put_Host('chilkat100.s3.amazonaws.com');

// We want to continue downloading a file.
// The relative local filepath of our previously partially downoaded file is: qa_output/hamlet.xml
// Let's find out how many bytes are already downloaded.
$fac = new CkFileAccess();
$localFilepath = 'qa_output/hamlet.xml';
// Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
// the size of the file as a string, then convert to an integer value.
$sz = $fac->FileSize($localFilepath);
if ($sz > 0) {
    print 'sz = ' . $sz . "\n";

    // If the sz equals 42375 bytes, then we want to add a Range header that looks like this:
    // Range: bytes=42375-
    $sbRange = new CkStringBuilder();
    $sbRange->Append('bytes=');
    $sbRange->AppendInt($sz);
    $sbRange->Append('-');
    $rest->AddHeader('Range',$sbRange->getAsString());
    print 'Added Range: ' . $sbRange->getAsString() . "\n";
}

// Send the request to download the remainder of the file.
$success = $rest->SendReqNoBody('GET','/hamlet.xml');
if ($success != true) {
    print $rest->lastErrorText() . "\n";
    exit;
}

// Read the response header.
$responseStatusCode = $rest->ReadResponseHeader();
if ($responseStatusCode < 0) {
    print $rest->lastErrorText() . "\n";
    exit;
}

print 'Response status code = ' . $responseStatusCode . "\n";

// We expect a 200 or 206 response status if the file data is coming.
// Otherwise, we'll get a string response body with an error message(or no response body).
if (($responseStatusCode == 200) or ($responseStatusCode == 206)) {

    $bodyStream = new CkStream();

    // The stream's sink will be a file.
    // We will append to the file..
    $bodyStream->put_SinkFile($localFilepath);

    // Indicate that we wish to append to the output file.
    // The SinkFileAppend property was added in Chilkat v9.50.83
    $bodyStream->put_SinkFileAppend(true);

    // Read the response body to the stream.  Given that we've
    // set the stream's sink to a file, it will stream directly
    // to the file.
    $success = $rest->ReadRespBodyStream($bodyStream,true);
    if ($success != true) {
        print $rest->lastErrorText() . "\n";
        exit;
    }

    print 'Successfully downloaded the file.' . "\n";

}
else {
    $errResponse = $rest->readRespBodyString();
    if ($rest->get_LastMethodSuccess() != true) {
        print $rest->lastErrorText() . "\n";
    }
    else {
        print $errResponse . "\n";
    }

}


?>