Delphi DLL

Azure Service Bus - Read Queued Message

See more Azure Service Bus Examples

Demonstrates read a message from an Azure Service Bus Queue. The message is received and removed from the queue. 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;
queueName: PWideChar;
sbToken: HCkStringBuilder;
sbPath: HCkStringBuilder;
sbResponseBody: HCkStringBuilder;
message: PWideChar;

begin
success := False;

// 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 := 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;

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

// Receive and delete a message from a queue named "gila";
queueName := 'gila';

// 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));

// Build the path..
sbPath := CkStringBuilder_Create();
CkStringBuilder_Append(sbPath,'/');
CkStringBuilder_Append(sbPath,queueName);
CkStringBuilder_Append(sbPath,'/messages/head');

// Add timeout and api-version query parameters.
CkRest_AddQueryParam(rest,'timeout','20');
CkRest_AddQueryParam(rest,'api-version','2013-08');

// Use the DELETE HTTP verb to read the message at the head of the queue and remove it.
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 message is the contents of the response body.
message := CkStringBuilder__getAsString(sbResponseBody);
Memo1.Lines.Add('Dequeued message: ' + message);

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

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

end;