Advanced Queuing - Oracle

General Features of Advanced Queuing
}
Message Format Transformation
}
You can define transformation mappings between different message payload types.
Transformation mappings are defined as SQL expressions that can include PL/SQL
functions (including callouts) and Java stored procedures. Only one-to-one message
transformations are supported. The transformation engine is tightly integrated with
Advanced Queuing to facilitate transformation of messages as they move through
the database messaging system. Figure 8–1 shows how transformations are
integrated with Advanced Queuing.
Figure 8–1 Transformations Integrated with Advanced Queuing
Enqueue(M)
Trans1
Queue1
Transformation mappings can be used during enqueue, dequeue, and propagation
operations. To use a transformation at enqueue, the mapping is specified in the
enqueue options. To use a transformation at dequeue, the mapping is specified
either in the dequeue options or when you add a subscriber. A mapping specified in
the dequeue options overrides a mapping specified with ADD_SUBSCRIBER. To use
a transformation at propagation, the mapping is specified when you add a
subscriber.
PL/SQL (DBMS_TRANSFORM Package): Scenario and Code
In the BooksOnLine application, assume that the order type is represented
differently in the order entry and the shipping applications.
8-6 Oracle9i Application Developer’s Guide - Advanced Queuing
M'
M'
M'
Trans2
Trans3
M''
M'''
Dequeue(M'')
Propagate(M''')
Trans1
Trans2
Trans3
(m, m')
(m', m'')
(m', m'')
Where M, M', M'' and M''' are messages of
types m, m', m'' and m''', respectively.