This component names database objects.

object_name := VARCHAR2
object_name := [schema_name.]name

This naming convention applies to queues, queue tables, and object types.

Names for objects are specified by an optional schema name and a name. If the schema name is not specified, then the current schema is assumed. The name must follow the reserved character guidelines in Oracle Database SQL Language ReferenceOracle Database SQL Language Reference. The schema name, agent name, and the object type name can each be up to 128 bytes long. However starting from 12c Release 2 (12.2.), queue names and queue table names can be a maximum of 122 bytes.

This component defines queue types.

type_name := VARCHAR2
type_name := object_type | "RAW"

The maximum number of attributes in the object type is limited to 900.

To store payloads of type RAW, Oracle Database Advanced Queuing creates a queue table with a LOB column as the payload repository. The size of the payload is limited to 32K bytes of data. Because LOB columns are used for storing RAW payload, the Oracle Database Advanced Queuing administrator can choose the LOB tablespace and configure the LOB storage by constructing a LOB storage string in the storage_clause parameter during queue table creation time.

This component identifies a producer or consumer of a message.

TYPE AQ$_AGENT IS OBJECT (
   name            VARCHAR2(30), 
   address         VARCHAR2(1024),
   protocol        NUMBER);

All consumers that are added as subscribers to a multiconsumer queue must have unique values for the AQ$_AGENT parameters. Two subscribers cannot have the same values for the NAME, ADDRESS, and PROTOCOL attributes for the AQ$_AGENT type. At least one of the three attributes must be different for two subscribers.

You can add subscribers by repeatedly using the DBMS_AQADM.ADD_SUBSCRIBER procedure up to a maximum of 1024 subscribers for a multiconsumer queue.

This type has three attributes:

• name

  This attribute specifies the name of a producer or a consumer of a message. It can be the name of an application or a name assigned by an application. A queue can itself be an agent, enqueuing or dequeuing from another queue. The name must follow the reserved character guidelines in Oracle Database SQL Language Reference.

• address

  This attribute is interpreted in the context of protocol. If protocol is 0 (default), then address is of the form [schema.]queue[@dblink].

• protocol

  This attribute specifies the protocol to interpret the address and propagate the message. The default value is 0.

This component identifies the list of agents that receive a message.

TYPE AQ$_RECIPIENT_LIST_T IS TABLE OF aq$_agent
           INDEX BY BINARY_INTEGER;
 

This component identifies the list of agents for DBMS_AQ.LISTEN to listen for.

TYPE AQ$_AGENT_LIST_T IS TABLE OF aq$_agent 
           INDEX BY BINARY INTEGER; 

This component identifies the list of subscribers that subscribe to this queue.

TYPE AQ$_SUBSCRIBER_LIST_T IS TABLE OF aq$_agent
          INDEX BY BINARY INTEGER;

This component identifies the list of registrations to a queue.

TYPE AQ$_REG_INFO_LIST AS VARRAY(1024) OF sys.aq$_reg_info;

This component identifies the list of anonymous subscriptions to which messages are posted.

TYPE AQ$_POST_INFO_LIST AS VARRAY(1024) OF sys.aq$_post_info;

This component identifies a producer or a consumer of a message.

TYPE SYS.AQ$_REG_INFO IS OBJECT (
   name                              VARCHAR2(128),
   namespace                         NUMBER,
   callback                          VARCHAR2(4000),
   context                           RAW(2000)  DEFAULT NULL,
   qosflags                          NUMBER,
   timeout                           NUMBER
   ntfn_grouping_class               NUMBER,
   ntfn_grouping_value               NUMBER    DEFAULT 600,
   ntfn_grouping_type                NUMBER,
   ntfn_grouping_start_time          TIMESTAMP WITH TIME ZONE,
   ntfn_grouping_repeat_count   NUMBER);

Its attributes are described in the following list.

This component specifies the Oracle Database Advanced Queuing descriptor received by AQ PL/SQL callbacks upon notification.

TYPE SYS.AQ$_DESCRIPTOR IS OBJECT (
   queue_name      VARCHAR2(61),
   consumer_name   VARCHAR2(30),
   msg_id          RAW(16),
   msg_prop        MSG_PROP_T,
   gen_desc        AQ$_NTFN_DESCRIPTOR,
   msgid_array     SYS.AQ$_NTFN_MSGID_ARRAY, 
   ntfnsRecdInGrp  NUMBER);

It has the following attributes:

The message properties type msg_prop_t has these components.

TYPE AQ$_MSG_PROP_T IS OBJECT(
   priority         number,
   delay            number,
   expiration       number,
   correlation      varchar2(128),
   attempts         number,
   recipent_list    aq$_recipient_list_t,
   exception_queue  varchar2(51),
   enqueue_time     date,
   state            number,
   sender_id        aq$_agent,
   original_misgid  raw(16),
   delivery_mode    number);

The timeout specifications type AQ$_NTFN_DESCRIPTOR has a single component:

TYPE AQ$_NTFN_DESCRIPTOR IS OBJECT(
   NTFN_FLAGS   number);

NTFN_FLAGS is set to 1 if the notifications are already removed after a stipulated timeout; otherwise the value is 0.

This component specifies anonymous subscriptions to which you want to post messages.

TYPE SYS.AQ$_POST_INFO IS OBJECT (
  name       VARCHAR2(128),
  namespace  NUMBER,
  payload    RAW(2000));

It has three attributes:

• name

  This attribute specifies the name of the anonymous subscription to which you want to post.

• namespace

  This attribute specifies the namespace of the anonymous subscription. To receive notifications from other applications using DBMS_AQ.POST or OCISubscriptionPost(), the namespace must be DBMS_AQ.NAMESPACE_ANONYMOUS.

• payload

  This attribute specifies the payload to be posted to the anonymous subscription. The default is NULL.

This component is for storing grouping notification data for AQ namespace, value 2³⁰ which is the max varray size.

TYPE SYS.AQ$_NTFN_MSGID_ARRAY AS VARRAY(1073741824)OF RAW(16);

When enumerated constants such as INFINITE, TRANSACTIONAL, and NORMAL_QUEUE are selected as values, the symbol must be specified with the scope of the packages defining it.

All types associated with the administrative interfaces must be prepended with DBMS_AQADM. For example:

DBMS_AQADM.NORMAL_QUEUE

Table 2-3 lists the enumerated constants in the Oracle Database Advanced Queuing administrative interface.

When using enumerated constants such as BROWSE, LOCKED, and REMOVE, the PL/SQL constants must be specified with the scope of the packages defining them.

All types associated with the operational interfaces must be prepended with DBMS_AQ. For example:

DBMS_AQ.BROWSE

Table 2-4 lists the enumerated constants in the Oracle Database Advanced Queuing operational interface.

These topics describe the background processes of Oracle Database Advanced Queuing.

• Queue Monitor Processes

• Job Queue Processes

• AQ Background Architecture