Subscriber PL/SQL procedure runs as SYS instead of user

Question

I am trying to figure out why the PL/SQL procedures ran via the AQ subscription are running as user SYS instead of the user that created the subscriber and registered the procedure. Following is the script I used to add the subscriber and register the procedure. All this happens under user SCOTT. The creation of the queues happened under SCOTT as well. The enqueing of the message happens via a procedure in SCOTT, initiated by SCOTT. Scott also has
GRANT execute ON dbms_aq to SCOTT;
GRANT execute on dbms_aqadm to SCOTT;
--ADD SUBSCRIBERS AND REGISTER THE QUEUES
begin
dbms_aqadm.add_subscriber
(queue_name => 'in_drv_queue',
subscriber => sys.aq$_agent('XML_drv', null, null),
rule => 'tab.user_data.queue_type = ''XML''' );
dbms_aqadm.add_subscriber
(queue_name => 'in_drv_queue',
subscriber => sys.aq$_agent('nonXML_drv', null, null),
rule => 'tab.user_data.queue_type = ''NON XML''' );
end;
begin
dbms_aq.register
(sys.aq$_reg_info_list
(sys.aq$_reg_info('in_drv_queue:XML_drv',
DBMS_AQ.NAMESPACE_AQ,
'plsql://scott.dequeue_xml',
HEXTORAW('FF')) ),
1);
dbms_aq.register
(sys.aq$_reg_info_list
(sys.aq$_reg_info('in_drv_queue:nonXML_drv',
DBMS_AQ.NAMESPACE_AQ,
'plsql://scott.dequeue_nonxml',
HEXTORAW('FF')) ),
1);
commit;
end;
Can anyone provide any suggestions as to why the two dequeue_ procedures run as SYS instead of SCOTT? I'm not sure what I am missing from the various examples I have read.
Thanks
Jason

Answer 1

I'm not familiar with the Audit Trail you refer to, but the following is one possible option to know what user the session is "running as"
SQL> select sys_context('userenv','client_info') from dual;
SYS_CONTEXT('USERENV','CLIENT_
SQL>
SQL> begin
  2     dbms_application_info.set_client_info('Testing');
  3  end;
  4  /
PL/SQL procedure successfully completed
SQL> select sys_context('userenv','client_info') from dual;
SYS_CONTEXT('USERENV','CLIENT_
Testing