Altering a Subscriber

Figure 9-21 Use Case Diagram: Alter a Subscriber

Text description of the illustration adq09qad24.gif

To refer to the table of all basic operations having to do with the Administrative Interface see: "Use Case Model: Administrative Interface -- Basic Operations"

Purpose

Alter existing properties of a subscriber to a specified queue. Only the rule can be altered.

Usage Notes

The rule, the transformation, or both can be altered. If you only alter one of the attributes, the rule, or the transformation of the subscriber, specify the existing value of the other attribute to the alter call.

When a queue, queue table, or subscriber is created, modified, or dropped, and if GLOBAL_TOPIC_ENABLED = TRUE, a corresponding LDAP entry is also created.

Syntax

See Chapter 3, "AQ Programmatic Environments" for a list of available functions in each programmatic environment. Use the following syntax references for each programmatic environment:

• PL/SQL (DBMS_AQADM Package): Oracle9i Supplied PL/SQL Packages and Types Reference DBMS_AQADM, ALTER_SUBSCRIBER procedure

• Visual Basic (OO4O): There is no applicable syntax reference for this use case

• Java (JDBC): Oracle9i Supplied Java Packages Reference oracle.AQ, alterSubscriber

Examples

See Chapter 3, "AQ Programmatic Environments" for a list of available functions in each programmatic environment. Examples are provided in the following programmatic environments:

• PL/SQL (DBMS_AQADM): Altering Subscriber

• VB (OO4O): Example not provided.

• Java (JDBC): Altering a Subscriber

PL/SQL (DBMS_AQADM): Altering Subscriber

Note: You may need to set up the following data structures for certain examples to work: EXECUTE DBMS_AQADM.CREATE_QUEUE_TABLE ( queue_table => 'aq.multi_qtab', multiple_consumers => TRUE, queue_payload_type => 'aq.message_typ', compatible => '8.1.5'); EXECUTE DBMS_AQADM.CREATE_QUEUE ( queue_name => 'multi_queue', queue_table => 'aq.multi_qtab');

/* Add a subscriber with a rule: */ 
DECLARE 
   subscriber       sys.aq$_agent; 
BEGIN 
   subscriber := sys.aq$_agent('SUBSCRIBER1', 'aq2.msg_queue2@london', null); 
   DBMS_AQADM.ADD_SUBSCRIBER(
      queue_name         =>    'aq.msg_queue', 
      subscriber         =>     subscriber, 
      rule               =>    'priority < 2'); 
END; 
/* Change rule for subscriber: */ 
DECLARE 
   subscriber          sys.aq$_agent; 
BEGIN 
   subscriber := sys.aq$_agent('SUBSCRIBER1', 'aq2.msg_queue2@london', null); 
   DBMS_AQADM.ALTER_SUBSCRIBER(
      queue_name         =>    'aq.msg_queue', 
      subscriber         =>     subscriber, 
      rule              =>     'priority = 1'); 
END; 

Add a Subscriber with a Transformation

/* Add a subscriber with transformation */ 
EXECUTE DBMS_AQADM.ADD_SUBSCRIBER
   ('aq.msg_queue',
     aq$_agent('subscriber1',
        'aq2.msg_queue2@london',
            null),
'AQ.MSG_MAP1');
/* Alter the subscriber*/ 
EXECUTE DBMS_AQADM.ALTER_SUBSCRIBER
   ('aq.msg_queue',
     aq$_agent ('subscriber1',
      'aq2.msg_queue2@london',
                null),
       'AQ.MSG.MAP2');

Java (JDBC): Altering a Subscriber

/* Alter the rule for a subscriber */
public static void example(AQSession aq_sess) throws AQException
{
     AQQueue         queue;
     AQAgent         agent1;        
     AQAgent         agent2;        

     /* Get the queue object */
     queue = aq_sess.getQueue("AQ", "multi_queue");

     /* add a subscriber */
     agent1 = new AQAgent("subscriber1", "aq2.msg_queue2@london");

     queue.alterSubscriber(agent1, "priority=1");
}