When you create Q subscriptions, you specify which WebSphere® MQ queues to send the data over
by associating each Q subscription with a replication queue map. You
can create a replication queue map before you begin creating Q subscriptions
or as one of the steps of creating Q subscriptions.
Before you begin
- Plan how you want to group replication queue maps and Q subscriptions.
- On the server that contains the source tables for the Q subscriptions,
create the control tables for the Q Capture program.
- On the server that contains the target tables for the Q subscriptions,
create the control tables for the Q Apply program.
- Ensure that you have defined the appropriate objects in WebSphere MQ.
Restrictions
The
same send queue cannot be used for both Q Replication and Event Publishing
because a send queue can transport compact messages (for Q Replication)
or XML messages (for Event Publishing), but not both.
Procedure
To create a replication queue map, use one of the following
methods:
| Method |
Description |
|---|
| ASNCLP command-line program |
Use the CREATE REPLQMAP command. For example, the following
commands set the environment and create a replication queue map SAMPLE_ASN1_TO_TARGET_ASN1
:ASNCLP SESSION SET TO Q REPLICATION;
SET SERVER CAPTURE TO DB SAMPLE;
SET CAPTURE SCHEMA SOURCE ASN1;
SET SERVER TARGET TO DB TARGET;
SET APPLY SCHEMA ASN1;
SET RUN SCRIPT LATER;
CREATE REPLQMAP
SAMPLE_ASN1_TO_TARGET_ASN1 USING
ADMINQ "ASN1.QM1.ADMINQ"
RECVQ "ASN1.QM1_TO_QM2.DATAQ"
SENDQ "ASN1.QM1_TO_QM2.DATAQ"
NUM APPLY AGENTS 8 HEARTBEAT INTERVAL 5;
|
| Replication Center |
Use the Create Replication Queue Map window.
You can open the window from the Servers page of the Create Q Subscription
wizard, or from the object tree expand the appropriate Q Capture or
Q Apply schema, right-click the Replication Queue Maps folder,
and select Create. |
Tip: You can use either replication administration
tool to validate the send queue, receive queue, and administration
queue that you specify for a replication queue map and to send test
messages between the queues. To validate, use the VALIDATE WSMQ ENVIRONMENT
FOR command in the ASNCLP or click Validate queues on
the Create Replication Queue Map window in the Replication Center.
To send test messages, use the VALIDATE WSMQ MESSAGE FLOW FOR REPLQMAP
command in the ASNCLP or the Validate WebSphere MQ
Queues window in the Replication Center.
When you create
a replication queue map, you can specify the following options:
- Send queue
- The WebSphere MQ queue where the Q Capture
program sends source transactions and informational messages. When
you define a replication queue map, you must select a send queue that
is configured to transport compact messages.
- Receive queue
- The WebSphere MQ queue from which the Q Apply
program receives source transactions and informational messages.
- Administration queue
- The queue that the Q Apply program uses to send control messages
to the Q Capture program. The messages that the Q Apply program sends
on this queue have several purposes, including telling a Q Capture
program to start sending messages or initiating the loading process
for a target table.
- Maximum message length
- The maximum size (in kilobytes) of a message that the Q Capture
program can put on this send queue. This maximum message length must
be less than or equal to the WebSphere MQ maximum message
size attribute (MAXMSGL) that is defined for the queue or queue manager.
- Queue error action
- The action that the Q Capture program take when a send queue is
no longer accepting messages because of an error, for example when
the queue is full:
- Stops running
- Stops putting messages on the
queue in error but continues to put messages on other queues
- Number of Q Apply agents
- The number of threads, or agents, that the Q Apply program uses
for concurrently applying transactions from this receive queue. To
request that transactions be applied in the order that they were received
from the source table, specify only one Q Apply agent. To have changes
applied to the target server in parallel, specify more than one Q
Apply agent.
- Maximum Q Apply memory usage
- The maximum amount of memory (in megabytes) that the Q Apply program
uses as a buffer for messages from this receive queue.
- Heartbeat interval
- How often, in milliseconds,
that the Q Capture program sends messages on this queue to tell the
Q Apply program that the Q Capture program is still running when there
are no transactions to replicate. The heartbeat is sent on the first
commit interval after the heartbeat interval expires. A value of 0
tells the Q Capture program not to send heartbeat messages.
This
heartbeat interval is different from the WebSphere MQ
parameter HBINT (heartbeat interval) that you can define for a WebSphere MQ channel.
Q Replication and Event Publishing