Delphi DLL

Azure Service Bus - Delete Message

See more Azure Service Bus Examples

Deletes a message from a queue or subscription.

For more information, see https://docs.microsoft.com/en-us/rest/api/servicebus/unlock-message

Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
rest: HCkRest;
bAutoReconnect: Boolean;
sbToken: HCkStringBuilder;
topicName: PWideChar;
subscriptionName: PWideChar;
messageId: PWideChar;
lockToken: PWideChar;
sbPath: HCkStringBuilder;
numReplaced: Integer;
sbResponseBody: HCkStringBuilder;

begin
success := False;

// 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 := CkRest_Create();
bAutoReconnect := True;
success := CkRest_Connect(rest,'<yournamespace>.servicebus.windows.net',443,True,bAutoReconnect);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// 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 := CkStringBuilder_Create();
CkStringBuilder_LoadFile(sbToken,'qa_data/tokens/serviceBusSas.txt','utf-8');

// Tell the REST object to use the Azure Shared Access Signature for authorization.
CkStringBuilder_Prepend(sbToken,'SharedAccessSignature ');
CkRest_AddHeader(rest,'Authorization',CkStringBuilder__getAsString(sbToken));

// ----------------------------------------------------------------------------------------------
// 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..
// ----------------------------------------------------------------------------------------------

// To delete a message, we'll need either the SequenceNumber or MessageId.
// When the message was peek-locked, the SequenceNumber and MessageId of the locked message
// was returned in the HTTP response header named "BrokerProperties, which contained
// JSON such as the following:
// 
// 	{
// 	  "DeliveryCount": 1,
// 	  "EnqueuedSequenceNumber": 3000004,
// 	  "EnqueuedTimeUtc": "Wed, 07 Dec 2016 17:42:48 GMT",
// 	  "Label": "M3",
// 	  "LockToken": "6eeee205-e541-4cb6-95fb-4c81da5f6858",
// 	  "LockedUntilUtc": "Thu, 08 Dec 2016 00:57:32 GMT",
// 	  "MessageId": "e8028116d63c43f191577f2789b1cca7",
// 	  "SequenceNumber": 4,
// 	  "State": "Active",
// 	  "TimeToLive": 922337193600
// 	}
// 
// 
// The path for unlocking a message is constructed as follows, depending on
// whether it is a message on a queue or subscription:
// 
// (for a queue)
// /{queuePath}/messages/{messageId|sequenceNumber}/{lockToken}
// 
// (for a subscription)
// /{topicPath}/subscriptions/{subscriptionName}/messages/{messageId|sequenceNumber}/{lockToken}

// This example will build a path to delete a message contained in a subscription.
topicName := 'gilaMonster';
subscriptionName := 'feedings';
messageId := 'e8028116d63c43f191577f2789b1cca7';
lockToken := '6eeee205-e541-4cb6-95fb-4c81da5f6858';

// Build the path..
sbPath := CkStringBuilder_Create();
CkStringBuilder_Append(sbPath,'/{topicPath}/subscriptions/{subscriptionName}/messages/{messageId|sequenceNumber}/{lockToken}');
numReplaced := CkStringBuilder_Replace(sbPath,'{topicPath}',topicName);
numReplaced := CkStringBuilder_Replace(sbPath,'{subscriptionName}',subscriptionName);
numReplaced := CkStringBuilder_Replace(sbPath,'{messageId|sequenceNumber}',messageId);
numReplaced := CkStringBuilder_Replace(sbPath,'{lockToken}',lockToken);

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

// Use the DELETE HTTP verb to delete the message.
sbResponseBody := CkStringBuilder_Create();
success := CkRest_FullRequestNoBodySb(rest,'DELETE',CkStringBuilder__getAsString(sbPath),sbResponseBody);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

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

// Check for a success response.
if (CkRest_getResponseStatusCode(rest) <> 200) then
  begin
    Memo1.Lines.Add(CkRest__lastRequestStartLine(rest));
    Memo1.Lines.Add(CkRest__lastRequestHeader(rest));
    Memo1.Lines.Add(CkStringBuilder__getAsString(sbResponseBody));
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// If successful, the response body would be empty..
Memo1.Lines.Add('Success.');

CkRest_Dispose(rest);
CkStringBuilder_Dispose(sbToken);
CkStringBuilder_Dispose(sbPath);
CkStringBuilder_Dispose(sbResponseBody);

end;