Channel definition commands
Cluster attributes that can be specified on channel definition commands.
The DEFINE CHANNEL
, ALTER CHANNEL
,
and DISPLAY CHANNEL
commands have two specific CHLTYPE parameters
for clusters: CLUSRCVR and CLUSSDR.
To define a cluster-receiver channel you use the DEFINE CHANNEL
command,
specifying CHLTYPE(CLUSRCVR)
. Many attributes on
a cluster-receiver channel definition are the same as the attributes
on a receiver or sender-channel definition. To define a cluster-sender
channel you use the DEFINE CHANNEL
command, specifying CHLTYPE(CLUSSDR)
,
and many of the same attributes as you use to define a sender-channel.
It
is no longer necessary to specify the name of the full repository
queue manager when you define a cluster-sender channel. If you know
the naming convention used for channels in your cluster, you can make
a CLUSSDR definition using the +QMNAME+
construction.
The +QMNAME+
construction is not supported on z/OS®. After connection, WebSphere® MQ changes the name
of the channel and substitutes the correct full repository queue manager
name in place of +QMNAME+
. The resulting channel
name is truncated to 20 characters.
For more information on naming conventions, see Cluster naming conventions.
The
technique works only if your convention for naming channels includes
the name of the queue manager. For example, you define a full repository
queue manager called QM1
in a cluster called CLUSTER1
with
a cluster-receiver channel called CLUSTER1.QM1.ALPHA
.
Every other queue manager can define a cluster-sender channel to this
queue manager using the channel name, CLUSTER1.+QMNAME+.ALPHA
.
If
you use the same naming convention for all your channels, be aware
that only one +QMNAME+
definition can exist at one
time.
DEFINE CHANNEL
and ALTER
CHANNEL
commands are specific to cluster channels: - CLUSTER
- The CLUSTER attribute specifies the name of the cluster with which this channel is associated. Alternatively use the CLUSNL attribute.
- CLUSNL
- The CLUSNL attribute specifies a namelist of cluster names.
- NETPRTY
- Cluster-receivers only.
- CLWLPRTY
- The CLWLPRTY parameter applies a priority factor to channels to the same destination for workload management purposes. This parameter specifies the priority of the channel for the purposes of cluster workload distribution. The value must be in the range zero through 9, where zero is the lowest priority and 9 is the highest.
- CLWLRANK
- The CLWLRANK parameter applies a ranking factor to a channel for workload management purposes. This parameter specifies the rank of a channel for the purposes of cluster workload distribution. The value must be in the range zero through 9, where zero is the lowest rank and 9 is the highest.
- CLWLWGHT
- The CLWLWGHT parameter applies a weighting factor to a channel for workload management purposes.CLWLWGHT weights the channel so that the proportion of messages sent down that channel can be controlled. The cluster workload algorithm uses CLWLWGHT to bias the destination choice so that more messages can be sent over a particular channel. By default all channel weight attributes are the same default value. The weight attribute allows you to allocate a channel on a powerful UNIX machine a larger weight than another channel on small desktop PC. The greater weight means that the cluster workload algorithm selects the UNIX machine more frequently than the PC as the destination for messages.
- CONNAME
- The CONNAME specified on a cluster-receiver channel definition is used throughout the cluster to identify the network address of the queue manager. Take care to select a value for the CONNAME parameter that resolves throughout your WebSphere MQ cluster. Do not use a generic name. Remember that the value specified on the cluster-receiver channel takes precedence over any value specified in a corresponding cluster-sender channel.
DEFINE CHANNEL
command
and ALTER CHANNEL
command also apply to the DISPLAY
CHANNEL
command.DISPLAY CHANNEL
command
does not display auto-defined channels. However, you can use the DISPLAY
CLUSQMGR
command to examine the attributes of auto-defined
cluster-sender channels.Use the DISPLAY CHSTATUS
command
to display the status of a cluster-sender or cluster-receiver channel.
This command gives the status of both manually defined channels and
auto-defined channels.
The equivalent PCFs are MQCMD_CHANGE_CHANNEL
, MQCMD_COPY_CHANNEL
, MQCMD_CREATE_CHANNEL
,
and MQCMD_INQUIRE_CHANNEL
.
Omitting the CONNAME value on a CLUSRCVR definition
In some circumstances you can omit the CONNAME value on a CLUSRCVR definition. You must not omit the CONNAME value on z/OS.
(1415)
The generated CONNAME is always in the dotted decimal (IPv4) or hexadecimal (IPv6) form,
rather than in the form of an alphanumeric DNS host name.This facility is useful when you have machines using Dynamic Host Configuration Protocol (DHCP). If you do not supply a value for the CONNAME on a CLUSRCVR channel, you do not need to change the CLUSRCVR definition. DHCP allocates you a new IP address.
If you specify a blank for the CONNAME on the CLUSRCVR definition, WebSphere MQ generates a CONNAME from the IP address of the system. Only the generated CONNAME is stored in the repositories. Other queue managers in the cluster do not know that the CONNAME was originally blank.
If
you issue the DISPLAY CLUSQMGR
command you see the
generated CONNAME. However, if you issue the DISPLAY
CHANNEL
command from the local queue manager, you see that
the CONNAME is blank.
If the queue manager is stopped and restarted with a different IP address, because of DHCP, WebSphere MQ regenerates the CONNAME and updates the repositories accordingly.