Advanced Queuing - Oracle

Dequeue Features
Rule-Based Subscription
}
m_property.setExceptionQueue("WS.WS_backorders_excpt_que");
obj_payload = message.getObjectPayload();
obj_payload.setPayloadData(back_order);
enq_option = new AQEnqueueOption();
/* Enqueue the message */
enq_msg_id = back_order_q.enqueue(enq_option, message);
db_conn.commit();
}
catch (Exception ex)
{
System.out.println("Exception: " + ex);
}
Messages can be routed to various recipients based on message properties or
message content. Users define a rule-based subscription for a given queue to specify
interest in receiving messages that meet particular conditions.
Rules are Boolean expressions that evaluate to TRUE or FALSE. Similar in syntax to
the WHERE clause of a SQL query, rules are expressed in terms of the attributes that
represent message properties or message content. These subscriber rules are
evaluated against incoming messages and those rules that match are used to
determine message recipients. This feature thus supports the notions of
content-based subscriptions and content-based routing of messages.
Subscription rules can also be defined on an attribute of type XMLType using XML
operators such as ExistsNode.
Scenario
For the BooksOnLine application, we illustrate how rule-based subscriptions are
used to implement a publish-subscribe paradigm utilizing content-based
subscription and content-based routing of messages. The interaction between the
Order Entry application and each of the Shipping Applications is modeled as
follows:
Western Region Shipping handles orders for the Western region of the U.S.
8-86 Oracle9i Application Developer’s Guide - Advanced Queuing