(Delphi DLL) Generate an AWS (S3) Pre-Signed URL to Download File

Demonstrates how to generate a pre-signed URL to download a file from the Amazon S3 service.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
http: HCkHttp;
bucketName: PWideChar;
objectName: PWideChar;
localFilePath: PWideChar;
awsService: PWideChar;
numSecondsValid: Integer;
bUseHttps: Boolean;
preSignedUrl: PWideChar;

begin
success := False;

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

http := CkHttp_Create();

CkHttp_putAwsAccessKey(http,'AWS_ACCESS_KEY');
CkHttp_putAwsSecretKey(http,'AWS_SECRET_KEY');

// Make sure to set your AWS region correctly
CkHttp_putAwsRegion(http,'us-east-1');

bucketName := 'chilkat100';
objectName := 'starfish/starfish.jpg';
localFilePath := 'qa_output/starfish.jpg';
awsService := 's3';

// The signed URL will be valid for this number of seconds:
numSecondsValid := 86400;

// Choose between a URL beginning with "http://" or "https://"...
bUseHttps := False;

// Generate the pre-signed URL
preSignedUrl := CkHttp__s3_GenPresignedUrl(http,'GET',bUseHttps,bucketName,objectName,numSecondsValid,awsService);
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// The following URL can be copy-and-pasted into a browser..
Memo1.Lines.Add('Pre-Signed AWS S3 URL: ' + preSignedUrl);

// Here's an example of a pre-signed URL. 
// This URL will only work within 1 day (86400 seconds) after the time this example was published.
// 
//     http://chilkat100.s3.amazonaws.com/starfish/starfish.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=16QXXDGY83AJJR6RVQ02%2F20170111%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20170111T161959Z&X-Amz-Expires=86400&X-Amz-SignedHeaders=host&X-Amz-Signature=72bf4fd9a15d7bbcdd313a3318d937a778905f62a3fbff9b789d8dc28acd9232

// Now try to do an HTTP Download using the signed URL.
success := CkHttp_Download(http,preSignedUrl,'c:/temp/qa_output/starfish.jpg');
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

Memo1.Lines.Add('Success.');

CkHttp_Dispose(http);

end;