(Delphi ActiveX) Azure File Service: Upload Large File

Sample code to upload a large file to a directory in a share in the Azure File Service. A file is uploaded by first creating the file in the Azure share and then writing ranges of bytes to the file. Azure imposes a 4MB limit for each PUT to write a range. Files larger than 4MB need to be uploaded by making multiple "Put Range" calls. This example uploads a large file requiring multiple "Put Range" calls.

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;
localFilePath: WideString;
fac: TCkFileAccess;
szLocalFile: Integer;
azAuth: TChilkatAuthAzureStorage;
sbFileSize: TChilkatStringBuilder;
responseStr: WideString;
sbRange: TChilkatStringBuilder;
sbResponseBody: TChilkatStringBuilder;
bdFileData: TChilkatBinData;
numBytesLeft: Integer;
curIndex: Integer;
chunkSize: Integer;

begin
// Azure File Service Example: Upload a large file.  
// See:  https://docs.microsoft.com/en-us/rest/api/storageservices/create-share
// also see: https://docs.microsoft.com/en-us/rest/api/storageservices/put-range

// 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.file.core.windows.net',port,bTls,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// This example will upload a larger file.
localFilePath := 'qa_data/zips/somethingBig.zip';
fac := TCkFileAccess.Create(Self);
// 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.
szLocalFile := fac.FileSize(localFilePath);
if (szLocalFile < 0) then
  begin
    Memo1.Lines.Add(fac.LastErrorText);
    Exit;
  end;

// Provide Azure Cloud credentials for the REST calls.
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 := 'File';
// 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: x-ms-date, Authorization.  These headers
// are automatically set by Chilkat.

// However, a few additional headers are required for the "Create File" operation:
rest.AddHeader('x-ms-type','file');

// This required header specifies the final size of the file (or the maximum size it can be).
sbFileSize := TChilkatStringBuilder.Create(Self);
sbFileSize.AppendInt(szLocalFile);
rest.AddHeader('x-ms-content-length',sbFileSize.GetAsString());

// Send a PUT request to create the file (or replace the file if it already exists).
// This will initialize the file in the Azure file storage.  To upload content, we'll need
// to do the "Put Range" operation one or more times.

// The following will create the file "somethingBig.zip" in the share "pip"
responseStr := rest.FullRequestNoBody('PUT','/pip/somethingBig.zip');
if (rest.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// When successful, the Azure File Service will respond with a 201 (Created) response status code,
// with no XML response body.  If an error response is returned, there will be an XML 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('Successfully created somethingBig.zip');

// --------------------------------------------------------------------------------
// Upload the file data...

// Make sure the headers from the "Create File" operation are removed.
rest.ClearAllHeaders();

// The x-ms-write header is required for each "Put Range" request.
rest.AddHeader('x-ms-write','update');

sbRange := TChilkatStringBuilder.Create(Self);
sbResponseBody := TChilkatStringBuilder.Create(Self);
bdFileData := TChilkatBinData.Create(Self);

// Open the file.  We'll be reading and uploading in chunks..
success := fac.OpenForRead(localFilePath);
if (success <> 1) then
  begin
    Memo1.Lines.Add(fac.LastErrorText);
    Exit;
  end;

numBytesLeft := szLocalFile;
curIndex := 0;
while numBytesLeft > 0 do
  begin

    chunkSize := numBytesLeft;
    // Azure allows for 4MB max chunks  (4 x 1024 x 1024 = 4194304)
    if (chunkSize > 4194304) then
      begin
        chunkSize := 4194304;
      end;

    // The only tricky part here is to correctly add the x-ms-range header.
    // It will be formatted like this:
    // x-ms-range: bytes=0-759623
    sbRange.Clear();
    sbRange.Append('bytes=');
    sbRange.AppendInt(curIndex);
    sbRange.Append('-');
    sbRange.AppendInt(curIndex + chunkSize - 1);

    // This replaces the header if it already exists..
    rest.AddHeader('x-ms-range',sbRange.GetAsString());

    // Read the next chunk from the local file.
    bdFileData.Clear();
    success := fac.FileReadBd(chunkSize,bdFileData.ControlInterface);

    success := rest.FullRequestBd('PUT','/pip/somethingBig.zip?comp=range',bdFileData.ControlInterface,sbResponseBody.ControlInterface);
    if (success <> 1) then
      begin
        // This would indicate a failure where no response was received.
        Memo1.Lines.Add(rest.LastErrorText);
        Exit;
      end;

    // A 201 response indicates the chunk was uploaded.
    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('Uploaded chunk from ' + IntToStr(curIndex) + ' to ' + IntToStr(curIndex + chunkSize - 1));

    curIndex := curIndex + chunkSize;
    numBytesLeft := numBytesLeft - chunkSize;
  end;

fac.FileClose();

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