(Delphi ActiveX) Azure Service Bus - Receive and Delete Message from Subscription

See more Azure Service Bus Examples

Shows how to receive and delete a message from an Azure service bus topic subscription.

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;
bAutoReconnect: Integer;
success: Integer;
sbToken: TChilkatStringBuilder;
topicName: WideString;
subscriptionName: WideString;
sbPath: TChilkatStringBuilder;
sbResponseBody: TChilkatStringBuilder;
message: WideString;

begin
// Note: Requires Chilkat v9.5.0.65 or greater.

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

// Make the initial connection.
// A single REST object, once connected, can be used for many Azure Service Bus REST API calls.
// The auto-reconnect indicates that if the already-established HTTPS connection is closed,
// then it will be automatically re-established as needed.
rest := TChilkatRest.Create(Self);
bAutoReconnect := 1;
success := rest.Connect('<yournamespace>.servicebus.windows.net',443,1,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// ----------------------------------------------------------------------------------------------
// The code above this comment could be placed inside a function/subroutine within the application
// because the connection does not need to be made for every request.  Once the connection is made
// the app may send many requests..
// ----------------------------------------------------------------------------------------------

// Let's load a previously computed SAS token and use it.
// See Azure Shared Access Signature for an example to genenerate an Azure SAS token.
sbToken := TChilkatStringBuilder.Create(Self);
sbToken.LoadFile('qa_data/tokens/serviceBusSas.txt','utf-8');

// Tell the REST object to use the Azure Shared Access Signature for authorization.
sbToken.Prepend('SharedAccessSignature ');
rest.AddHeader('Authorization',sbToken.GetAsString());

// ----------------------------------------------------------------------------------------------

// Receive a message from the subscription "feedings" in the topic "gilaMonster"
topicName := 'gilaMonster';
subscriptionName := 'feedings';

// Build the path..
sbPath := TChilkatStringBuilder.Create(Self);
sbPath.Append('/');
sbPath.Append(topicName);
sbPath.Append('/subscriptions/');
sbPath.Append(subscriptionName);
sbPath.Append('/messages/head');

// Add a timeout parameter.
rest.AddQueryParam('timeout','20');

// Use the DELETE HTTP verb to read the message at the head of the queue and remove it.
sbResponseBody := TChilkatStringBuilder.Create(Self);
success := rest.FullRequestNoBodySb('DELETE',sbPath.GetAsString(),sbResponseBody.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Response Status Code = ' + IntToStr(rest.ResponseStatusCode));

// Check for a success response.
if (rest.ResponseStatusCode <> 200) then
  begin
    Memo1.Lines.Add(rest.LastRequestStartLine);
    Memo1.Lines.Add(rest.LastRequestHeader);
    Memo1.Lines.Add(sbResponseBody.GetAsString());
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// If successful, the message is the contents of the response body.
message := sbResponseBody.GetAsString();
Memo1.Lines.Add('Received message: ' + message);

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