Creating a Queue

Figure 9-6 Use Case Diagram: Creating a Queue

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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

Create a queue in the specified queue table.

Usage Notes

• Queue names and queue table names are converted to upper case. Mixed case (upper and lower case together) is not supported.

• All queue names must be unique within a schema. Once a queue is created with CREATE_QUEUE, it can be enabled by calling START_QUEUE. By default, the queue is created with both enqueue and dequeue disabled.

• To view retained messages, you can either dequeue by message ID or use SQL.

• When a queue, queue table, or subscriber is created 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, CREATE_QUEUE procedure

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

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

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 Package): Dropping a Queue Table

• VB (OO4O): Example not provided.

• Java (JDBC): Dropping a Queue Table

PL/SQL (DBMS_AQADM): Creating a Queue

Create a queue within a queue table for messages of object type

/* Create a message type: */
CREATE type aq.Message_typ as object (
   Subject     VARCHAR2(30),
   Text        VARCHAR2(80));   

/* Create a object type queue table and queue: */
EXECUTE dbms_aqadm.create_queue_table (
   Queue_table        => 'aq.ObjMsgs_qtab',
   Queue_payload_type => 'aq.Message_typ');

EXECUTE dbms_aqadm.create_queue (
   Queue_name         =>  'msg_queue',
   Queue_table        => 'aq.ObjMsgs_qtab');

Create a queue within a queue table for messages of RAW type

/* Create a RAW type queue table and queue: */
EXECUTE dbms_aqadm.create_queue_table ( 
   Queue_table          => 'aq.RawMsgs_qtab', 
   Queue_payload_type   => 'RAW'); 
  
/* Create queue: */
EXECUTE dbms_aqadm.create_queue ( 
   Queue_name          => 'raw_msg_queue', 
   Queue_table         => 'aq.RawMsgs_qtab'); 
  

Create a prioritized message queue table and queue

Caution: You may need to set up or drop data structures for certain examples to work:

/* Create a queue table for priortized messages: */
EXECUTE dbms_aqadm.create_queue_table (
   Queue_table        => 'aq.PriorityMsgs_qtab', 
   Sort_list          => 'PRIORITY,ENQ_TIME', 
   Queue_payload_type => 'aq.Message_typ');
/* Create queue: */
EXECUTE dbms_aqadm.create_queue (
   Queue_name         => 'priority_msg_queue', 
   Queue_table        => 'aq.PriorityMsgs_qtab');

Create a queue table and queue meant for multiple consumers

Caution: You may need to set up or drop data structures for certain examples to work:

/* Create a queue table for multi-consumers: */
EXECUTE dbms_aqadm.create_queue_table (
   queue_table        => 'aq.MultiConsumerMsgs_qtab',
   Multiple_consumers => TRUE, 
   Queue_payload_type => 'aq.Message_typ');

/* Create queue: */
EXECUTE dbms_aqadm.create_queue (
   Queue_name         => 'MultiConsumerMsg_queue',
   Queue_table        => 'aq.MultiConsumerMsgs_qtab');

Create a queue table and queue to demonstrate propagation

/* Create queue: */
EXECUTE dbms_aqadm.create_queue (
   Queue_name        => 'AnotherMsg_queue',
   queue_table       => 'aq.MultiConsumerMsgs_qtab');

Create a queue table and queue for multiple consumers compatible with 8.1

/* Create a queue table for multi-consumers compatible with Release 8.1: */
EXECUTE dbms_aqadm.create_queue_table ( 
   Queue_table        => 'aq.MultiConsumerMsgs81_qtab', 
   Multiple_consumers => TRUE, 
   Compatible         => '8.1', 
   Queue_payload_type => 'aq.Message_typ'); 
 
EXECUTE dbms_aqadm.create_queue ( 
   Queue_name         => 'MultiConsumerMsg81_queue', 
   Queue_table        => 'aq.MultiConsumerMsgs81_qtab'); 

Java (JDBC): Creating a Queue

Create a queue within a queue table for messages of object type

public static void example(AQSession aq_sess) throws AQException
{
     AQQueueProperty         queue_prop;
     AQQueueTable            q_table;
     AQQueue                 queue;

     q_table = aq_sess.getQueueTable ("aq", "ObjMsgs_qtab");

     /* Create a new AQQueueProperty object: */
     queue_prop = new AQQueueProperty();

     queue = aq_sess.createQueue (q_table, "msg_queue", queue_prop);
     System.out.println("Successful createQueue");  

}

Create a queue within a queue table for messages of raw type

public static void example(AQSession aq_sess) throws AQException
{
     AQQueueProperty         queue_prop;
     AQQueueTable            q_table;
     AQQueue                 queue;

     q_table = aq_sess.getQueueTable ("aq", "RawMsgs_qtab");

     /* Create a new AQQueueProperty object: */
     queue_prop = new AQQueueProperty();

     queue = aq_sess.createQueue (q_table, "msg_queue", queue_prop);
     System.out.println("Successful createQueue");  

}

Create a Multi-Consumer queue with prioritized messages

public static void example(AQSession aq_sess) throws AQException
{
     AQQueueTableProperty    qtable_prop;
     AQQueueProperty         queue_prop;
     AQQueueTable            q_table;
     AQQueue                 queue;
     AQAgent                 agent;

     qtable_prop = new AQQueueTableProperty("RAW"); 
     qtable_prop.setMultiConsumer(true);

     qtable_prop.setSortOrder("priority,enq_time");
     q_table = aq_sess.createQueueTable ("aq", "PriorityMsgs_qtab", 
					 qtable_prop);

     queue_prop = new AQQueueProperty();
     queue = aq_sess.createQueue (q_table, "priority_msg_queue", queue_prop);

}