AMQP1 | Send Message

Read first AMQP1 Sender Links to know how to create a Sender Link.

 

Send Message

Use the method SendMessage passing the Session and SenderLink name to send a text message to the AMQP1 Server. The method has the following parameters:

 

• Session: name of the session.
• Link: name of the sender link.
• Text: text of the message.
• MessageId: (optional) the id of the message, it can be used when using unsettled mode, to know if the server has processed the message.
• Options: (optional) allows customizing some options when sending the message.
  • Settled: when using a sender link in mixed mode, when sending a message the Settled property can be customized.
  • Await: if the message is unsettled, and the value is true, the code will wait till the message is processed by the server or the timeout has exceeded.
  • Timeout: value in milliseconds if await is true (by default 10000).
  • RaiseTimeoutException: if the timeout is exceeded, an exception is raised (by default true).

 

 

oAMQP1.SendMessage('MySession', 'MySenderLink', 'My first AMQP Message');

 

 

Await Send Message

By default, the SendMessage method is asynchronous when sending a message unsettled, setting the property Await to true, the client will wait till receives a confirmation from the server that the message has been processed.

 

procedure SendMessageAwait(const aSession, aSenderLink, aText: string);
var
  oOptions := TsgcAMQP1MethodOptions_SendMessageAck.Create;
begin
  Try
    oOptions.Settled := False;
    oOptions.Await := True;
    AMQP1.SendMessage(aSession, aSenderLink, aText, 'messsage-id', oOptions);
  Finally
    oOptions.Free;
  End;
end;

 

Events

When sending a message, there are 2 Events that can be used to know when the message is sent and if the message has been processed by the server (when sending unsettled).

 

• OnAMQPMessageSent: this event is called after the message is sent to the server. When calling the method SendMessage, the message is stored in an internal queue and processed by a secondary thread, so after the message is sent, this event is called.
• OnAMQPMessageSentAck: this event is called, when the client receives a confirmation that the message has been processed by the AMQP1 Server.

 

procedure OnAMQPMessageSentAck(Sender: TObject;
const aSession: TsgcAMQP1Session; const aLink: TsgcAMQP1SenderLink;
const aMessageId: string; const aDeliveryState: TsgcAMQP1FrameDeliveryStates;
const aDisposition: TsgcAMQP1FrameDisposition);
var
  vMessageId: string;
begin
  vMessageId := aMessageId;
  case aDeliveryState of
    amqp1fdtsAccepted:
      ShowMessage('#msg-accepted: ' + vMessageId);
    amqp1fdtsRejected:
      ShowMessage('#msg-rejected: ' + vMessageId + ' ' + TsgcAMQP1FrameRejected
        (aDisposition.State).Error.Condition + ' ' + TsgcAMQP1FrameRejected
        (aDisposition.State).Error.Description);
    amqp1fdtsReleased:
      ShowMessage('#msg-released: ' + vMessageId);
    amqp1fdtsModified:
      ShowMessage('#msg-modified: ' + vMessageId + ' ' + TsgcAMQP1FrameModified
        (aDisposition.State).MessageAnnotations);
    amqp1fdtsReceived:
      ShowMessage('#msg-received: ' + vMessageId);
  end;
end;