Oracle Database
Oracle Advanced Queuing (AQ)

비고

단순 생산자 / 소비자

개요

메시지를 보낼 수있는 대기열을 만듭니다. 오라클은 스토어드 프로 시저에 메시지를 대기열에 넣었고 처리해야 함을 알립니다. 또한 비상시에 사용할 수있는 몇 가지 서브 프로그램을 추가하여 메시지가 삭제되는 것을 막고, 다시 대기열에서 제외하고 모든 메시지를 처리하는 간단한 배치 작업을 실행합니다.

이 예제는 Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production에서 테스트되었습니다.

대기열 만들기

메시지 유형, 메시지를 보유 할 수있는 대기열 테이블 및 대기열을 작성합니다. 대기열의 메시지는 우선 순위에 따라 대기열에서 우선 대기 한 다음 대기열에 들어갑니다. 메시지가 제대로 작동하지 않고 큐에서 큐가 제거되면 AQ는 3600 초 후에 큐에서 큐를 제거 할 수있게합니다. 예외 대기열을 이동하기 전에이 작업을 48 번 수행합니다.

create type message_t as object 
   (
   sender  varchar2 ( 50 ),
   message varchar2 ( 512 )
   );
/
-- Type MESSAGE_T compiled
begin dbms_aqadm.create_queue_table(
     queue_table        => 'MESSAGE_Q_TBL',
     queue_payload_type => 'MESSAGE_T',
     sort_list          => 'PRIORITY,ENQ_TIME',
     multiple_consumers =>  false,
     compatible         => '10.0.0');
  end;
/
-- PL/SQL procedure successfully completed.
begin dbms_aqadm.create_queue(
     queue_name          => 'MESSAGE_Q',
     queue_table         => 'MESSAGE_Q_TBL',
     queue_type          =>  0,
     max_retries         =>  48,
     retry_delay         =>  3600,
     dependency_tracking =>  false);
  end;
/
-- PL/SQL procedure successfully completed.

이제 메시지를 넣을 장소가 생기면 대기열에서 메시지를 관리하고 작업하는 패키지를 만들 수 있습니다.

create or replace package message_worker_pkg
is
   queue_name_c constant varchar2(20) := 'MESSAGE_Q';
   
   -- allows the workers to process messages in the queue
   procedure enable_dequeue;

   -- prevents messages from being worked but will still allow them to be created and enqueued
   procedure disable_dequeue;

   -- called only by Oracle Advanced Queueing.  Do not call anywhere else.
   procedure on_message_enqueued (context        in raw,
                                  reginfo        in sys.aq$_reg_info,
                                  descr          in sys.aq$_descriptor,
                                  payload        in raw,
                                  payloadl       in number);

   -- allows messages to be worked if we missed the notification (or a retry
   -- is pending)
   procedure work_old_messages;
   
end;
/

create or replace package body message_worker_pkg
is
   -- raised by Oracle when we try to dequeue but no more messages are ready to
   -- be dequeued at this moment
   no_more_messages_ex          exception;
   pragma exception_init (no_more_messages_ex,
                          -25228);

   -- allows the workers to process messages in the queue
   procedure enable_dequeue
   as
   begin
      dbms_aqadm.start_queue (queue_name => queue_name_c, dequeue => true);
   end enable_dequeue;

   -- prevents messages from being worked but will still allow them to be created and enqueued
   procedure disable_dequeue
   as
   begin
      dbms_aqadm.stop_queue (queue_name => queue_name_c, dequeue => true, enqueue => false);
   end disable_dequeue;

   procedure work_message (message_in in out nocopy message_t)
   as
   begin
      dbms_output.put_line ( message_in.sender || ' says ' || message_in.message );
   end work_message;

   -- called only by Oracle Advanced Queueing.  Do not call anywhere else.

   procedure on_message_enqueued (context        in raw,
                                  reginfo        in sys.aq$_reg_info,
                                  descr          in sys.aq$_descriptor,
                                  payload        in raw,
                                  payloadl       in number)
   as
      pragma autonomous_transaction;
      dequeue_options_l      dbms_aq.dequeue_options_t;
      message_id_l           raw (16);
      message_l              message_t;
      message_properties_l   dbms_aq.message_properties_t;
   begin
      dequeue_options_l.msgid         := descr.msg_id;
      dequeue_options_l.consumer_name := descr.consumer_name;
      dequeue_options_l.wait          := dbms_aq.no_wait;
      dbms_aq.dequeue (queue_name           => descr.queue_name,
                       dequeue_options      => dequeue_options_l,
                       message_properties   => message_properties_l,
                       payload              => message_l,
                       msgid                => message_id_l);
      work_message (message_l);
      commit;
   exception
      when no_more_messages_ex
      then
         -- it's possible work_old_messages already dequeued the message
         commit;
      when others
      then
         -- we don't need to have a raise here.  I just wanted to point out that
         -- since this will be called by AQ throwing the exception back to it
         -- will have it put the message back on the queue and retry later
         raise;
   end on_message_enqueued;

   -- allows messages to be worked if we missed the notification (or a retry
   -- is pending)
   procedure work_old_messages
   as
      pragma autonomous_transaction;
      dequeue_options_l      dbms_aq.dequeue_options_t;
      message_id_l           raw (16);
      message_l              message_t;
      message_properties_l   dbms_aq.message_properties_t;
   begin
      dequeue_options_l.wait       := dbms_aq.no_wait;
      dequeue_options_l.navigation := dbms_aq.first_message;

      while (true) loop -- way out is no_more_messages_ex
         dbms_aq.dequeue (queue_name           => queue_name_c,
                          dequeue_options      => dequeue_options_l,
                          message_properties   => message_properties_l,
                          payload              => message_l,
                          msgid                => message_id_l);
         work_message (message_l);
         commit;
      end loop;
   exception
      when no_more_messages_ex
      then
         null;
   end work_old_messages;
end;

다음으로 메시지가 MESSAGE_Q에 대기열에 올려지고 (커밋 된) 우리의 절차에 알리면 수행해야 할 작업이 있음을 AQ에 알리십시오. AQ는이 세션을 처리하기 위해 자체 세션에서 작업을 시작합니다.

begin
  dbms_aq.register (
     sys.aq$_reg_info_list (
        sys.aq$_reg_info (user || '.' || message_worker_pkg.queue_name_c,
                          dbms_aq.namespace_aq,
                          'plsql://' || user || '.message_worker_pkg.on_message_enqueued',
                          hextoraw ('FF'))),
     1);
  commit;
end; 

대기열 시작 및 메시지 보내기

declare
   enqueue_options_l      dbms_aq.enqueue_options_t;
   message_properties_l   dbms_aq.message_properties_t;
   message_id_l           raw (16);
   message_l              message_t;
begin
   -- only need to do this next line ONCE
   dbms_aqadm.start_queue (queue_name => message_worker_pkg.queue_name_c, enqueue => true , dequeue => true);
   
   message_l := new message_t ( 'Jon', 'Hello, world!' );
   dbms_aq.enqueue (queue_name           => message_worker_pkg.queue_name_c,
                    enqueue_options      => enqueue_options_l,
                    message_properties   => message_properties_l,
                    payload              => message_l,
                    msgid                => message_id_l);
   commit;
end;