Oracle® Streams Advanced Queuing User's Guide and Reference Release 10.1 Part Number B10785-01 |
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After Oracle Messaging Gateway (MGW) is loaded and set up, it is ready to be configured and run. This chapter describes how to manage the Messaging Gateway agent and how to configure propagation.
This chapter contains these topics:
Messages are propagated between Oracle Streams AQ and non-Oracle messaging systems by the Messaging Gateway agent. The Messaging Gateway agent runs as an external process of the Oracle Database server.
You must set the following information in order for the agent to start:
The Messaging Gateway agent runs as a process external to the database. To access Oracle Streams AQ and the Messaging Gateway packages, the Messaging Gateway agent needs to establish connections to the database. You can use DBMS_MGWADM.DB_CONNECT_INFO
to set the username, password and the database connect string that the Messaging Gateway agent will use for creating database connections. The user must be granted the role MGW_AGENT_ROLE
before the Messaging Gateway agent can be started.
You can call DBMS_MGWADM.DB_CONNECT_INFO
to alter connection information when the Messaging Gateway agent is running.
Example 20-1 shows Messaging Gateway being configured for user mgwagent
with password mgwagent_password
using net service name mydatabase
.
You can use DBMS_MGWADM.ALTER_AGENT
to set the maximum number of messaging connections used by the Messaging Gateway agent, the heap size of the Messaging Gateway agent process, and the number of propagation threads in the agent process. The default values are one connection, 64 MB of memory heap, and one propagation thread.
Example 20-2 sets the number of database connections to two, the heap size to 64MB, and the number of propagation threads to two.
Example 20-2 Setting the Resource Limits
SQL> exec dbms_mgwadm.alter_agent(max_connections => 2, max_memory => 64, max_threads => 2);
You can alter the maximum number of connections when the Messaging Gateway agent is running. The memory heap size and the number of propagation threads cannot be altered when the Messaging Gateway agent is running. Example 20-3 updates the maximum number of connections to three but leaves the maximum memory and the number of propagation threads unchanged.
This section contains these topics:
After the Messaging Gateway agent is configured, you can start the agent with DBMS_MGWADM.STARTUP
, as shown in Example 20-4.
You can use the MGW_GATEWAY
view to check the status of the Messaging Gateway agent, as described in Chapter 22, " Monitoring Oracle Messaging Gateway".
You can use DBMS_MGWADM.SHUTDOWN
to shut down the Messaging Gateway agent, as shown in Example 20-5.
You can use the MGW_GATEWAY
view to check if the Messaging Gateway agent has shut down successfully, as described in Chapter 22, " Monitoring Oracle Messaging Gateway".
Messaging Gateway uses a job queue job to start the Messaging Gateway agent. This job is created when procedure DBMS_MGWADM.STARTUP
is called. When the job is run, it calls an external procedure that creates the Messaging Gateway agent in an external process. The job is removed after:
The agent shuts down because DBMS_MGWADM.SHUTDOWN
was called
The agent terminates because a non-restartable error occurs
The DBMS_JOB
package creates a repeatable job with a repeat interval of two minutes. The job is owned by SYS
. A repeatable job enables the Messaging Gateway agent to restart automatically when a given job instance ends because of a database shutdown, database malfunction, or a restartable error. Only one instance of an Messaging Gateway agent job runs at a given time.
If the agent job encounters an error, then the error is classified as either a restartable error or non-restartable error. A restartable error indicates a problem that might go away if the agent job were to be restarted. A non-restartable error indicates a problem that is likely to persist and be encountered again if the agent job restarts. ORA-01089 (immediate shutdown in progress) and ORA-28576 (lost RPC connection to external procedure) are examples of restartable errors. ORA-06520 (error loading external library) is an example of a non-restartable error.
Messaging Gateway uses a database shutdown trigger. If the Messaging Gateway agent is running on the instance being shut down, then the trigger notifies the agent of the shutdown, and upon receipt of the notification, the agent will terminate the current run. The job scheduler will automatically schedule the job to run again at a future time.
If an Messaging Gateway agent job instance ends because of a database malfunction or a restartable error detected by the agent job, then the job will not be removed and the job scheduler will automatically schedule the job to run again at a future time.
The MGW_GATEWAY
view shows the agent status, the job identifier, and the database instance on which the Messaging Gateway agent is currently running.
See Also: |
While the Messaging Gateway job startup and shutdown principles are the same for RAC and non-RAC environments, there are some things to keep in mind for a RAC environment.
Only one Messaging Gateway agent process can be running at a given time, even in a RAC environment. The job scheduler determines which database instance will run a job based on parameters specified when the job is created. The DBMS_MGWADM.STARTUP
procedure has two optional parameters, instance
and force
, that can be used to set the instance affinity of the Messaging Gateway agent job.
When a database instance is shut down in a RAC environment, the Messaging Gateway shutdown trigger will notify the agent to shut down only if the Messaging Gateway agent is running on the instance being shut down. The job scheduler will automatically schedule the job to be run again at a future time, either on another instance, or if the job can only run on the instance being shut down, when that instance is restarted.
Running as a client of non-Oracle messaging systems, the Messaging Gateway agent communicates with non-Oracle messaging systems through messaging system links. A messaging system link is a set of connections between the Messaging Gateway agent and a non-Oracle messaging system.
To configure a messaging system link of a non-Oracle messaging system, users must provide information for the agent to make connections to the non-Oracle messaging system. Users can specify the maximum number of messaging connections.
When configuring a messaging system link for a non-Oracle messaging system that supports transactions and persistent messages, the native name of log queues for inbound and outbound propagation must be specified in order to guarantee exactly-once message delivery. The log queues should be used only by the Messaging Gateway agent. No other programs should enqueue or dequeue messages of the log queues. The inbound log queue and outbound log queue can refer to the same physical queue, but better performance can be achieved if they refer to different physical queues.
When configuring a messaging system link, users can also specify an options
argument. An options
argument is a set of {name, value} pairs of type SYS.MGW_PROPERTY
.
This section contains these topics:
A WebSphere MQ Base Java link is created by calling DBMS_MGWADM.CREATE_MSGSYSTEM_LINK
with the following information provided:
Interface type: DBMS_MGWADM.MQSERIES_BASE_JAVA_INTERFACE
WebSphere MQ connection information:
Host name and port number of the WebSphere MQ server
Queue manager name
Channel name
User name and password
Maximum number of messaging connections allowed
Log queue names for inbound and outbound propagation
Optional information such as:
Send, receive, and security exits
Character sets
Example 20-6 configures a WebSphere MQ Base Java link 'mqlink'
. The link is configured to use the WebSphere MQ queue manager 'my.queue.manager'
on host 'myhost.mydomain'
and port 1414, using WebSphere MQ channel 'mychannel'
.
This example also sets the option to register a WebSphere MQ SendExit class. The class 'mySendExit'
must be in the CLASSPATH set in mgw.ora
.
Example 20-6 Configuring a WebSphere MQ Base Java Link
declare v_options sys.mgw_properties; v_prop sys.mgw_mqseries_properties; begin v_prop := sys.mgw_mqseries_properties.construct(); v_prop.interface_type := dbms_mgwadm.MQSERIES_BASE_JAVA_INTERFACE; v_prop.max_connections := 1; v_prop.username := 'mqm'; v_prop.password := 'mqm'; v_prop.hostname := 'myhost.mydomain'; v_prop.port := 1414; v_prop.channel := 'mychannel'; v_prop.queue_manager := 'my.queue.manager'; v_prop.outbound_log_queue := 'mylogq'; -- Specify a WebSphere MQ send exit class 'mySendExit' to be associated with -- the queue. -- Note that this is used as an example of how to use the options parameter, -- but is not an option that is usually set. v_options := sys.mgw_properties(sys.mgw_property('MQ_SendExit', 'mySendExit')); dbms_mgwadm.create_msgsystem_link( linkname => 'mqlink', properties => v_prop, options => v_options ); end;
See Also:
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A WebSphere MQ JMS link is created by calling DBMS_MGWADM.CREATE_MSGSYSTEM_LINK
with the following information provided:
Interface type
Java Message Service (JMS) distinguishes between queue and topic connections. Each type of connection can be used only for operations involving that JMS destination type:
A WebSphere MQ JMS queue link must be created with interface type DBMS_MGWADM.JMS_QUEUE_CONNECTION
to access WebSphere MQ JMS queues
A WebSphere MQ JMS topic link must be created with interface type DBMS_MGWADM.JMS_TOPIC_CONNECTION
to access WebSphere MQ JMS topics
WebSphere MQ connection information:
Host name and port number of the WebSphere MQ server
Queue manager name
Channel name
User name and password
Maximum number of messaging connections allowed
A messaging connection is mapped to a JMS session.
Log destination (JMS queue or JMS topic) for inbound and outbound propagation
The log destination type must match the link type:
For a WebSphere MQ JMS queue link, the log queue name must be the name of a physical WebSphere MQ JMS queue created using WebSphere MQ administration tools.
For a WebSphere MQ JMS topic link, the log queue name must be the name of a WebSphere MQ JMS topic. The physical WebSphere MQ queue used by that topic must be created using WebSphere MQ administration tools. By default, the physical queue used is SYSTEM.JMS.D.SUBSCRIBER.QUEUE
. A link option can be used to specify a different physical queue.
Optional information such as:
Send, receive, and security exits
Character sets
WebSphere MQ publish/subscribe configuration used for JMS topics
Example 20-7 configures an Messaging Gateway link to a WebSphere MQ queue manager using a JMS topic interface. The link is named 'mqjmslink'
and is configured to use the WebSphere MQ queue manager 'my.queue.manager'
on host 'myhost.mydomain'
and port 1414, using WebSphere MQ channel 'mychannel'
.
This example also uses the options
parameter to specify a nondefault durable subscriber queue to be used with the log topic.
Example 20-7 Configuring a WebSphere MQ JMS Link
declare v_options sys.mgw_properties; v_prop sys.mgw_mqseries_properties; begin v_prop := sys.mgw_mqseries_properties.construct(); v_prop.max_connections := 1; v_prop.interface_type := dbms_mgwadm.JMS_TOPIC_CONNECTION; v_prop.username := 'mqm'; v_prop.password := 'mqm'; v_prop.hostname := 'myhost.mydomain'; v_prop.port := 1414; v_prop.channel := 'mychannel'; v_prop.queue_manager := 'my.queue.manager'; v_prop.outbound_log_queue := 'mylogtopic' -- Specify a WebSphere MQ durable subscriber queue to be used with the -- log topic. v_options := sys.mgw_properties( sys.mgw_property('MQ_JMSDurSubQueue', 'myDSQueue')); dbms_mgwadm.create_msgsystem_link( linkname => 'mqjmslink', properties => v_prop, options => v_options ); end;
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A TIB/Rendezvous link is created by calling DBMS_MGWADM.CREATE_MSGSYSTEM_LINK
with three parameters (service
, network
and daemon
) for the agent to create a corresponding transport of TibrvRvdTransport
type.
A TIB/Rendezvous message system link does not need propagation log queues. Logging information is stored in memory. Therefore, Messaging Gateway can only guarantee at-most-once message delivery.
Example 20-8 configures a TIB/Rendezvous link named 'rvlink'
that connects to the rvd
daemon on the local computer.
Example 20-8 Configuring a TIB/Rendezvous Link
declare v_options sys.mgw_properties; v_prop sys.mgw_tibrv_properties; begin v_prop := sys.mgw_tibrv_properties.construct(); dbms_mgwadm.create_msgsystem_link(linkname => 'rvlink', properties => v_prop); end;
See Also: "DBMS_MGWADM" in PL/SQL Packages and Types Reference for information on TIB/Rendezvous system properties and supported options |
Some link information can be altered after the link is created. You can alter link information with the Messaging Gateway agent running or shut down. Example 20-9 alters the link 'mqlink'
to change the max_connections
and password
properties.
Example 20-9 Altering a WebSphere MQ Link
declare v_options sys.mgw_properties; v_prop sys.mgw_mqseries_properties; begin -- use alter_construct() for initialization v_prop := sys.mgw_mqseries_properties.alter_construct(); v_prop.max_connections := 2; v_prop.password := 'newpasswd'; dbms_mgwadm.alter_msgsystem_link( linkname => 'mqlink', properties => v_prop); end;
See Also: "DBMS_MGWADM" in PL/SQL Packages and Types Reference for restrictions on changes when the Messaging Gateway agent is running |
You can remove an Messaging Gateway link to a non-Oracle messaging system with DBMS_MGWADM.REMOVE_MSGSYSTEM_LINK
, but only if all registered queues associated with this link have already been unregistered. The link can be removed with the Messaging Gateway agent running or shut down. Example 20-10 removes the link 'mqlink'
.
You can use the MGW_LINKS
view to check links that have been created. It lists the name and link type, as shown in Example 20-11.
Example 20-11 Listing All Messaging Gateway Links
SQL> select link_name, link_type from MGW_LINKS; LINK_NAME LINK_TYPE ------------------------ MQLINK MQSERIES RVLINK TIBRV
You can use the MGW_MQSERIES_LINK
and MGW_TIBRV_LINKS
views to check messaging system type-specific configuration information, as shown in Example 20-12.
Example 20-12 Checking Messaging System Link Configuration Information
SQL> select link_name, queue_manager, channel, hostname from mgw_mqseries_link; LINK_NAME QUEUE_MANAGER CHANNEL HOSTNAME ---------------------------------------------------------- MQLINK my.queue.manager mychannel myhost.mydomain SQL> select link_name, service, network, daemon from mgw_tibrv_links; LINK_NAME SERVICE NETWORK DAEMON ----------------------------------------------------- RVLINK
All non-Oracle messaging system queues involved in propagation as a source queue, destination queue, or exception queue must be registered through the Messaging Gateway administration interface. You do not need to register Oracle Streams AQ queues involved in propagation.
This section contains these topics:
Registering a non-Oracle queue provides information for the Messaging Gateway agent to access the queue. However, it does not create the physical queue in the non-Oracle messaging system. The physical queue must be created using the non-Oracle messaging system administration interfaces before the Messaging Gateway agent accesses the queue.
The following information is used to register a non-Oracle queue:
Name of the messaging system link used to access the queue
Native name of the queue (its name in the non-Oracle messaging system)
Domain of the queue
DBMS_MGWADM.DOMAIN_QUEUE
for a point-to-point queue
DBMS_MGWADM.DOMAIN_TOPIC
for a publish/subscribe queue
Options specific to the non-Oracle messaging system
These options are a set of {name, value} pairs, both of which are strings.
See Also: "DBMS_MGWADM" in PL/SQL Packages and Types Reference for optional foreign queue configuration properties |
Example 20-13 shows how to register the WebSphere MQ Base Java queue my_mq_queue
as an Messaging Gateway queue 'destq'
.
Example 20-13 Registering a WebSphere MQ Base Java Queue
begin dbms_mgwadm.register_foreign_queue( name => 'destq', linkname => 'mqlink', provider_queue => 'my_mq_queue', domain => dbms_mgwadm.DOMAIN_QUEUE); end;
The domain must be DBMS_MGWADM.DOMAIN_QUEUE
or NULL, because only point-to-point queues are supported for WebSphere MQ.
When registering a WebSphere MQ JMS queue, the domain must be DBMS_MGWADM.DOMAIN_QUEUE
, and the linkname
parameter must refer to a WebSphere MQ JMS queue link.
When registering a WebSphere MQ JMS topic, the domain must be DBMS_MGWADM.DOMAIN_TOPIC
, and the linkname
parameter must refer to a WebSphere MQ JMS topic link. The provider_queue
for a WebSphere MQ JMS topic used as a propagation source may include wildcards. See WebSphere MQ documentation for wildcard syntax.
The domain of a registered TIB/Rendezvous queue must be DBMS_MGWADM.DOMAIN_TOPIC
or NULL. The provider_queue
of the queue is a TIB/Rendezvous subject.
A registered TIB/Rendezvous queue with provider_queue
set to a wildcard subject name can be used as a propagation source queue for inbound propagation. It is not recommended to use queues with wildcard subject names as propagation destination queues or exception queues. As documented in TIB/Rendezvous, sending messages to wildcard subjects can trigger unexpected behavior. However, neither Messaging Gateway nor TIB/Rendezvous prevents you from doing so.
A non-Oracle queue can be unregistered with DBMS_MGWADM.UNREGISTER_FOREIGN_QUEUE
, but only if there are no subscribers or schedules referencing it.
Example 20-14 unregisters the queue 'destq'
of the link 'mqlink'
.
You can use the MGW_FOREIGN_QUEUES
view to check which non-Oracle queues are registered and what link each uses, as shown in Example 20-15.
Propagating messages between an Oracle Streams AQ queue and a non-Oracle messaging system queue requires a propagation job. A propagation job consists of a propagation subscriber and a propagation schedule. The propagation subscriber specifies the source and destination queues, while the propagation schedule specifies when the propagation job is processed. A propagation schedule is associated with a propagation subscriber that has the same propagation source, destination, and type.
You can create a propagation job to propagate messages between JMS destinations. You can also create a propagation job to propagate messages between non-JMS queues. Messaging Gateway does not support message propagation between a JMS destination and a non-JMS queue.
This section contains these topics:
A propagation subscriber specifies what messages are propagated and how the messages are propagated.
Messaging Gateway allows bi-directional message propagation. An outbound propagation moves messages from Oracle Streams AQ to non-Oracle messaging systems. An inbound propagation moves messages from non-Oracle messaging systems to Oracle Streams AQ.
If the propagation source is a queue (point-to-point), then the Messaging Gateway agent moves all messages from the source queue to the destination queue. If the propagation source is a topic (publish/subscribe), then the Messaging Gateway agent creates a subscriber of the propagation source queue in the messaging system. The agent only moves messages that are published to the source queue after the subscriber is created.
When propagating a message, the Messaging Gateway agent converts the message from the format in the source messaging system to the format in the destination messaging system. Users can customize the message conversion by providing a message transformation. If message conversion fails, then the message will be moved to an exception queue, if one has been provided, so that the agent can continue to propagate messages for the subscriber.
An Messaging Gateway exception queue is different from an Oracle Streams AQ exception queue. Messaging Gateway moves a message to an Messaging Gateway exception queue when message conversion fails. Oracle Streams AQ moves a message to an Oracle Streams AQ exception queue after MAX_RETRIES
dequeue attempts on the message.
Messages moved to an Oracle Streams AQ exception queue may result in unrecoverable failures on the associated Messaging Gateway subscriber. To avoid the problem, the MAX_RETRIES
parameter of any Oracle Streams AQ queue that is used as the propagation source of an Messaging Gateway propagation job should be set to a value much larger than 16.
If the messaging system of the propagation source queue supports message selection, then a message selection rule can be specified for a propagation subscriber. Only messages that satisfy the message selector will be propagated.
Users can also specify subscriber options for certain types of propagation subscribers to control how messages are propagated, such as options for JMS message delivery mode and TIB/Rendezvous queue policies.
Messaging Gateway provides MGW_SUBSCRIBERS
and MGW_SCHEDULES
views for users to check configuration and status of Messaging Gateway subscribers and schedules.
Messaging Gateway subscribers are created by DBMS_MGWADM.ADD_SUBSCRIBER
.
If the propagation source for non-JMS propagation is an Oracle Streams AQ queue, then the queue must be a multiconsumer queue. Messaging Gateway creates a corresponding Oracle Streams AQ subscriber 'MGW_subscriber_id'
for the messaging system subscriber subscriber_id
when DBMS_MGWADM.ADD_SUBSCRIBER
is called.
If the propagation source is a JMS topic, such as an Oracle Java Message Service (OJMS) topic or a WebSphere MQ JMS topic, then a JMS subscriber 'MGW_subscriber_id'
is created on the topic in the source messaging system by the Messaging Gateway agent. If the agent is not running, then the subscriber will not be created until the agent is restarted.
If the propagation source is a queue, then only one propagation job can be created using that queue as the propagation source. If the propagation source is a topic, then multiple propagation jobs can be set up using that topic as the propagation source with each propagation job having its own corresponding subscriber on the topic in the messaging system.
Example 20-16 creates Messaging Gateway propagation subscriber sub_aq2mq
.
Example 20-16 Creating a Propagation Subscriber
begin dbms_mgwadm.add_subscriber( subscriber_id => 'sub_aq2mq', propagation_type => dbms_mgwadm.outbound_propagation, queue_name => 'mgwuser.srcq', destination => 'destq@mqlink'); end;
Note: If a WebSphere MQ JMS topic is involved in a propagation job, then a durable subscriberMGL_subscriber_id is created on the log topic. The durable subscriber is removed when the Messaging Gateway subscriber is successfully removed. |
A propagation subscriber is not processed until an associated propagation schedule is created and enabled. A propagation schedule is associated with a propagation subscriber when the propagation type, source and destination match.
The latency
parameter in a propagation schedule controls the polling interval of a propagation job. The polling interval determines how soon the agent can discover the available messages to propagate in the propagation source queue. The default polling interval is 5 seconds or the value set for oracle.mgw.polling_interval
in Messaging Gateway initialization file mgw.ora
.
Example 20-17 creates Messaging Gateway propagation schedule sch_aq2mq
.
A propagation job is enabled if its propagation schedule is created and enabled. A propagation job is disabled if its propagation schedule is disabled or removed. Users can call DBMS_MGWADM.ENABLE_PROPAGATION_SCHEDULE
to enable a propagation schedule and DBMS_MGWADM.DISABLE_PROPAGATION_SCHEDULE
to disable a propagation schedule.
Example 20-18 enables the propagation schedule for propagation subscriber sub_aq2mq
.
Example 20-18 Enabling an Messaging Gateway Propagation Schedule
begin dbms_mgwadm.enable_propagation_schedule('sch_aq2mq'); end;
Example 20-19 disables the propagation schedule for propagation subscriber sub_aq2mq
.
Example 20-19 Disabling an Messaging Gateway Propagation Schedule
begin dbms_mgwadm.disable_propagation_schedule('sch_aq2mq'); end;
By default, the propagation schedule is enabled when it is first created.
To create a propagation job that is initially disabled, call the following APIs in the indicated order:
DBMS_MGWADM.SCHEDULE_PROPAGATION
DBMS_MGWADM.DISABLE_PROPAGATION_SCHEDULE
DBMS_MGWADM.ADD_SUBSCRIBER
When a problem occurs with a propagation job, the Messaging Gateway agent retries the failed operation up to 16 times in an exponential backoff scheme before the propagation job stops. You can use DBMS_MGWADM.RESET_SUBSCRIBER
to reset the failure count to zero to allow the agent to retry the failed operation immediately.
Example 20-20 resets the failure count for propagation subscriber sub_aq2mq
.
After the propagation subscriber and schedule of a propagation job are created, you can alter the selection rule, transformation, exception queue, subscriber options, and latency of the propagation job. Subscribers and schedules can be altered with the Messaging Gateway agent running or shut down.
Example 20-21 adds an exception queue for subscriber sub_aq2mq
.
Example 20-21 Altering Propagation Subscriber by Adding an Exception Queue
begin dbms_mgwadm.alter_subscriber( subscriber_id => 'sub_aq2mq', exception_queue => 'mgwuser.my_ex_queue'); end;
Example 20-22 changes the polling interval for schedule sch_aq2mq
.
You can remove an Messaging Gateway propagation subscriber with DBMS_MGWADM.REMOVE_SUBSCRIBER
.
Before removing the Messaging Gateway subscriber from the Messaging Gateway configuration, Messaging Gateway does the following cleanup:
Removes from the messaging system the associated subscriber that may have been created by Messaging Gateway
Removes propagation log records from log queues for the subscriber being removed
Messaging Gateway may fail to do the cleanup because:
The Messaging Gateway agent is not running
Non-Oracle messaging system is not running
The Messaging Gateway agent is unable to interact with the source or destination messaging system
If Messaging Gateway cleanup fails for any reason, then the Messaging Gateway subscriber being removed is placed in the DELETE_PENDING
state. The Messaging Gateway agent tries to clean up subscribers in DELETE_PENDING
state when:
DBMS_MGWADM.REMOVE_SUBSCRIBER
is called and the Messaging Gateway agent is running
The Messaging Gateway agent is starting and finds a subscriber in DELETE_PENDING
state
You can specify DBMS_MGWADM.FORCE
when calling DBMS_MGWADM.REMOVE_SUBSCRIBER
to force Messaging Gateway to remove the Messaging Gateway subscriber from the Messaging Gateway configuration without placing it in the DELETE_PENDING
mode in case of cleanup failures.
Calling DBMS_MGWADM.REMOVE_SUBSCRIBER
with DBMS_MGWADM.FORCE
may result in obsolete log records in the log queues and subscriptions in messaging systems, which may cause unnecessary message accumulation. Oracle recommends not using DBMS_MGWADM.FORCE
when calling DBMS_MGWADM.REMOVE_SUBSCRIBER
, if possible.
Example 20-23 removes propagation subscriber sub_aq2mq
.
Example 20-23 Removing a Propagation Subscriber
begin dbms_mgwadm.remove_subscriber(subscriber_id =>'sub_aq2mq'); end;
You can remove propagation schedules with DBMS_MGWADM.UNSCHEDULE_PROPAGATION
. Removing a propagation schedule results in disabling the associated propagation job. It does not remove any subscriptions in messaging systems.
Example 20-24 removes propagation schedule sch_aq2mq
.