Advanced Queuing - Oracle

Working with Messaging Gateway
Messaging Gateway dequeues from the AQ source queue during propagation. A
transformation registered with an inbound subscriber is invoked by Advanced
Queuing when Messaging Gateway enqueues to the AQ destination queue during
propagation.
For example, trans_sampleadt_to_mgw_basic is a stored procedure
representing a transformation function with the following signature:
Transformation Function Signature: Example
FUNCTION trans_sampleadt_to_mgw_basic(in_msg IN mgwuser.sampleADT)
RETURN sys.mgw_basic_msg_t;
Create a transformation using DBMS_TRANSFORM.CREATE as follows:
begin
dbms_transform.create_transformation(
schema => 'mgwuser',
name => 'sample_adt_to_mgw_basic',
from_schema => 'mgwuser',
from_type => 'sampleadt',
to_schema => 'sys',
to_type => 'mgw_basic_msg_t',
transformation => 'mgwuser.trans_sampleadt_to_mgw_basic(user_data)');
end;
Once created, this transformation can be registered with Messaging Gateway when
creating a subscriber.
begin
dbms_mgwadm.add_subscriber(
subscriber_id => 'sub_aq2mq', -- MGW subscriber name
propagation_type => dbms_mgwadm.outbound_propagation, -- outbound propaga
queue_name => 'mgwuser.srcq', -- AQ queue name (source queue)
destination =>'destq@mqlink', -- MGW foreign queue with link
-- (destination queue)
transformation => ‘mgwuser.sample_adt_to_mgw_basic’); -- transformation
-- invoked on dequeue
end;
Exception Queues
The exception queue stores messages for which conversion has failed. This queue
must be on the same messaging system as the propagation source queue. If
specified, a message for which conversion fails is moved to the exception queue
18-24 Oracle9i Application Developer’s Guide - Advanced Queuing