Message Properties Type

The message_properties_t data structure describes the information that is used by AQ to manage individual messages. These are set at enqueue time, and their values are returned at dequeue time.

Syntax

TYPE message_properties_t IS RECORD (
   priority               BINARY_INTEGER DEFAULT 1,
   delay                  BINARY_INTEGER DEFAULT NO_DELAY,
   expiration             BINARY_INTEGER DEFAULT NEVER,
   correlation            VARCHAR2(128)  DEFAULT NULL,
   attempts               BINARY_INTEGER,
   recipient_list         aq$_recipient_list_t,
   exception_queue        VARCHAR2(51)   DEFAULT NULL,
   enqueue_time           DATE,
   state                  BINARY_INTEGER,
   sender_id              aq$_agent      DEFAULT NULL, 
   original_msgid         RAW(16)        DEFAULT NULL);

TYPE aq$_recipient_list_t IS TABLE OF sys.aq$_agent
   INDEX BY BINARY_INTEGER;

Attributes

Table 4-7 Message Properties Type Attributes

Attribute	Description
priority	Specifies/returns the priority of the message. A smaller number indicates higher priority. The priority can be any number, including negative numbers.
delay	Specifies/returns the delay of the enqueued message. The delay represents the number of seconds after which a message is available for dequeuing. Dequeuing by msgid overrides the delay specification. A message enqueued with delay set will be in the WAITING state, when the delay expires the messages goes to the READY state. DELAY processing requires the queue monitor to be started. Note that delay is set by the producer who enqueues the message. NO_DELAY: the message is available for immediate dequeuing. number: the number of seconds to delay the message.
expiration	Specifies/returns the expiration of the message. It determines, in seconds, the duration the message is available for dequeuing. This parameter is an offset from the delay. Expiration processing requires the queue monitor to be running. NEVER: message does not expire. number: number of seconds message remains in READY state. If the message is not dequeued before it expires, then it is moved to the exception queue in the EXPIRED state.
correlation	Returns the identification supplied by the producer for a message at enqueuing.
attempts	Returns the number of attempts that have been made to dequeue this message. This parameter cannot be set at enqueue time.
recipient_list	For type definition, see the "Agent". This parameter is only valid for queues which allow multiple consumers. The default recipients are the queue subscribers. This parameter is not returned to a consumer at dequeue time.
exception_queue	Specifies/returns the name of the queue to which the message is moved if it cannot be processed successfully. Messages are moved in two cases: The number of unsuccessful dequeue attempts has exceeded max_retries or the message has expired. All messages in the exception queue are in the EXPIRED state. The default is the exception queue associated with the queue table. If the exception queue specified does not exist at the time of the move, then the message is moved to the default exception queue associated with the queue table, and a warning is logged in the alert file. If the default exception queue is used, then the parameter returns a NULL value at dequeue time.
enqueue_time	Returns the time the message was enqueued. This value is determined by the system and cannot be set by the user. This parameter can not be set at enqueue time.
state	Returns the state of the message at the time of the dequeue. This parameter can not be set at enqueue time. 0: The message is ready to be processed. 1: The message delay has not yet been reached. 2: The message has been processed and is retained. 3: The message has been moved to the exception queue.
sender_id	Specifies/returns the application-specified sender identification. DEFAULT: NULL
original_msgid	This parameter is used by Oracle AQ for propagating messages. DEFAULT: NULL