The Request Update command message is sent from a subscriber to a broker, to request the current retained publications for the specified topic and subscription point that match the given (optional) filter.
This message is sent to SYSTEM.BROKER.CONTROL.QUEUE, the broker's control queue. Authority to put a message to this queue is required, in addition to access authority for the topic in the request update; this is set by the broker's system administrator.
This command is normally used if the subscriber specified the option PubOnReqOnly when it registered. If the broker has any matching retained publications, they are sent to the subscriber. If the broker has no matching retained publications, the request fails with return code MQRCCF_NO_RETAINED_MSG. The requester must have previously registered a subscription with the same Topic, SubPoint, and Filter values.
This property must be specified, but only one occurrence is allowed in this message.
If this property is omitted, the default subscription point is used.
The <Filter> property should have the same value as that specified on the original subscription for which you are now requesting an update.
If this property is omitted, no content filtering takes place.
The CorrelId in the message descriptor (MQMD), which must not be zero, is used when sending matching publications to the subscriber queue.
All options take their default values. This has the same effect as omitting the <RegOpt> property. If other options are specified at the same time, None is ignored.
When specified the identity of the subscriber (queue, queue manager, and correlid) is not restricted to a single userid. This differs from the existing behavior of the broker that associates the userid of the original registration message with the subscriber's identity and from then on prevents any other user using that identity. If a new subscriber tries to use the same identity, the command fails with return code MQRCCF_DUPLICATE_SUBSCRIPTION.
This allows any user to modify or deregister the subscription when they have suitable authority. Therefore, there is no need to check that the userid matches that of the original subscriber.
To add this option to an existing subscription, the command must come from the same userid as the original subscription.
If the subscription of the Request Update command has VariableUserId set, this must be set at request update time to indicate which subscription is referred to. Otherwise, the userid of the Request Update command is used to identify the subscription. This is overridden, along with the other subscriber identifiers, if a subscription name is supplied.
The default, if this property is omitted, is that no registration options are set.
If this property is omitted, the default is the ReplyToQMgr name in the message descriptor (MQMD). If the resulting name is blank, it defaults to the broker's QMgrName.
If this property is omitted, the default is the ReplyToQ name in the message descriptor (MQMD), which must not be blank in this case.
If VariableUserId is set, and the userid differs from that of the subscription, the command succeeds if the userid of the new command message has authority to browse the stream queue and put to the subscriber queue of the subscription. Otherwise, the command fails with return code MQRCCF_NOT_AUTHORIZED.
If a subscription exists that matches the traditional identity of this command, but has no SubName, theRequest Update command fails with return code MQRCCF_SUB_NAME_ERROR.
If an attempt is made to request an update for a subscription that has a SubName using a command message that matches the traditional identity, but with no SubName specified, the command succeeds.
<psc> <Command>ReqUpdate</Command> <RegOpt>CorrelAsId</RegOpt> <Topic>Sport/Soccer/State/LatestScore/#</Topic> </psc>
Notices |
Trademarks |
Downloads |
Library |
Support |
Feedback
![]() ![]() |
aq07000_ |