(Delphi ActiveX) Upload File in Blocks and Commit the Block List

See more Azure Cloud Storage Examples

Demonstrates how to upload a file in blocks and then commit the block list. For files larger than 64MB, this is the way to upload to Azure Storage. Azure limits the size of each block to a maximum of 4MB.

For more information, see https://learn.microsoft.com/en-us/rest/api/storageservices/put-block-list?tabs=microsoft-entra-id

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: TChilkatRest;
bTls: Integer;
port: Integer;
bAutoReconnect: Integer;
success: Integer;
azAuth: TChilkatAuthAzureStorage;
xml: TChilkatXml;
fac: TCkFileAccess;
blockSize: Integer;
numBlocks: Integer;
sbResponseBody: TChilkatStringBuilder;
uriPath: TChilkatStringBuilder;
blockId: WideString;
dataBlock: TChilkatBinData;
i: Integer;
xmlStr: WideString;
responseStr: WideString;

begin
// Azure Blob Service Example: Upload a file in blocks, and then commit the block list.
// See also: https://msdn.microsoft.com/en-us/library/azure/dd135726.aspx

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

rest := TChilkatRest.Create(Self);

// Connect to the Azure Storage Blob Service
bTls := 1;
port := 443;
bAutoReconnect := 1;
// In this example, the storage account name is "chilkat".
success := rest.Connect('chilkat.blob.core.windows.net',port,bTls,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// Provide Azure Cloud credentials for the REST call.
azAuth := TChilkatAuthAzureStorage.Create(Self);
azAuth.AccessKey := 'AZURE_ACCESS_KEY';
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.Account := 'chilkat';
azAuth.Scheme := 'SharedKey';
azAuth.Service := 'Blob';
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion := '2021-08-06';
success := rest.SetAuthAzureStorage(azAuth.ControlInterface);

// Note: The application does not need to explicitly set the following
// headers: Content-Length, x-ms-date, Authorization.  These headers
// are automatically set by Chilkat.

// As the blocks are uploaded, we'll keep an XML block list for the subsequent commit..
xml := TChilkatXml.Create(Self);
xml.Tag := 'BlockList';

// Any type of file can be uploaded in this way.  It can a text file, binary file, anything...
// This example will upload an XML file that is approximately 275K in size.  It can be downloaded
// at http://www.chilkatsoft.com/hamlet.xml
fac := TCkFileAccess.Create(Self);
success := fac.OpenForRead('qa_data/xml/hamlet.xml');
// Assuming success for the example..

// We'll upload in 16K blocks (normally a program would upload in larger block sizes than this,
// but this is just an example...)
blockSize := 16384;

// How many 16K blocks?  (Including 1 for the last partial block)
numBlocks := fac.GetNumBlocks(blockSize);

sbResponseBody := TChilkatStringBuilder.Create(Self);
uriPath := TChilkatStringBuilder.Create(Self);

dataBlock := TChilkatBinData.Create(Self);
i := 0;
while i < numBlocks do
  begin

    dataBlock.Clear();
    success := fac.ReadBlockBd(i,blockSize,dataBlock.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(fac.LastErrorText);
        Exit;
      end;

    // Generate a base64 block ID.  
    // (Chilkat provides a helper method named GenBlockId to make this easy)
    // A pre-base64 encoded block ID length of 4 is sufficient in this case because
    // this file certainly won't have more than 99,999 blocks..
    blockId := fac.GenBlockId(i,4,'base64');

    // Add this blockId to the list of blocks to be committed.
    xml.NewChild2('Latest',blockId);

    // Build the URI path
    uriPath.Clear();
    success := uriPath.Append('/mycontainer/hamlet.xml?comp=block&blockId=');
    success := uriPath.Append(blockId);

    // Upload this block..
    sbResponseBody.Clear();
    success := rest.FullRequestBd('PUT',uriPath.GetAsString(),dataBlock.ControlInterface,sbResponseBody.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(rest.LastErrorText);
        Exit;
      end;

    // Verify that we received a 201 status code.
    if (rest.ResponseStatusCode <> 201) then
      begin
        // Examine the request/response to see what happened.
        Memo1.Lines.Add('response status code = ' + IntToStr(rest.ResponseStatusCode));
        Memo1.Lines.Add('response status text = ' + rest.ResponseStatusText);
        Memo1.Lines.Add('response header: ' + rest.ResponseHeader);
        Memo1.Lines.Add('response body (if any): ' + sbResponseBody.GetAsString());
        Memo1.Lines.Add('---');
        Memo1.Lines.Add('LastRequestStartLine: ' + rest.LastRequestStartLine);
        Memo1.Lines.Add('LastRequestHeader: ' + rest.LastRequestHeader);
        Exit;
      end;

    i := i + 1;
  end;

fac.FileClose();

// Now commit the blocks.
// Let's have a look at the XML that will commit the blocks:
xmlStr := xml.GetXml();
Memo1.Lines.Add(xmlStr);

// The XML will look like this:

// <?xml version="1.0" encoding="utf-8" ?>
// <BlockList>
//     <Latest>MDAwMA==</Latest>
//     <Latest>MDAwMQ==</Latest>
//     <Latest>MDAwMg==</Latest>
//     <Latest>MDAwMw==</Latest>
//     <Latest>MDAwNA==</Latest>
//     <Latest>MDAwNQ==</Latest>
//     <Latest>MDAwNg==</Latest>
//     <Latest>MDAwNw==</Latest>
//     <Latest>MDAwOA==</Latest>
//     <Latest>MDAwOQ==</Latest>
//     <Latest>MDAxMA==</Latest>
//     <Latest>MDAxMQ==</Latest>
//     <Latest>MDAxMg==</Latest>
//     <Latest>MDAxMw==</Latest>
//     <Latest>MDAxNA==</Latest>
//     <Latest>MDAxNQ==</Latest>
//     <Latest>MDAxNg==</Latest>
//     <Latest>MDAxNw==</Latest>
// </BlockList>

// Send the PUT Block List...
responseStr := rest.FullRequestString('PUT','/mycontainer/hamlet.xml?comp=blocklist',xmlStr);
if (rest.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// When successful, the Azure Storage service will respond with a 201 response status code,
// with no response body.

if (rest.ResponseStatusCode <> 201) then
  begin
    // Examine the request/response to see what happened.
    Memo1.Lines.Add('response status code = ' + IntToStr(rest.ResponseStatusCode));
    Memo1.Lines.Add('response status text = ' + rest.ResponseStatusText);
    Memo1.Lines.Add('response header: ' + rest.ResponseHeader);
    Memo1.Lines.Add('response body (if any): ' + responseStr);
    Memo1.Lines.Add('---');
    Memo1.Lines.Add('LastRequestStartLine: ' + rest.LastRequestStartLine);
    Memo1.Lines.Add('LastRequestHeader: ' + rest.LastRequestHeader);
    Exit;
  end;

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