Author: buildbot
Date: Wed Oct 25 16:24:29 2017
New Revision: 1020038
Log:
Production update by buildbot for activemq
Modified:
websites/production/activemq/content/cache/main.pageCache
websites/production/activemq/content/per-destination-policies.html
websites/production/activemq/content/virtual-destinations.html
Modified: websites/production/activemq/content/cache/main.pageCache
==============================================================================
Binary files - no diff available.
Modified: websites/production/activemq/content/per-destination-policies.html
==============================================================================
--- websites/production/activemq/content/per-destination-policies.html
(original)
+++ websites/production/activemq/content/per-destination-policies.html Wed Oct
25 16:24:29 2017
@@ -71,7 +71,7 @@
<tbody>
<tr>
<td valign="top" width="100%">
-<div class="wiki-content maincontent"><p>We support a number of different
policies which can be attached to individual destinations (queues, topics) or
to wildcards of queue/topic hierarchies. This makes it easy to configure how
different regions of the JMS destination space are handled.</p><p>The
properties you can set on a Destination are as follows:</p><div
class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1"
rowspan="1" class="confluenceTh"><p>Common Property</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Default Value</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForConsumed</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message when a
message is consumed by a client.</p></td></tr><tr><td colspan="1" rowspan="1"
class="c
onfluenceTd"><p><code>advisoryForDelivery</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Send an advisory message when a message is
sent to a client.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForFastProducers</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message if a
producer is deemed fast.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForSlowConsumers</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message if a
consumer is deemed slow.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryWhenFull</code></p></td><td colspan="1"
rowspan="1" class="conf
luenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Send an advisory message when a limit (memory, store,
temp disk) is full.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>enableAudit</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td colspan="1"
rowspan="1"
class="confluenceTd"><p>When <strong><code>true</code></strong> the broker
will track duplicate messages. Duplicates can happen for non-persistent
messages during failover.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>gcInactiveDestinations</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Garbage collect inactive
destinations.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>inactiveTimoutBeforeGC</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd">
<p><code>5000</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The timeout (in ms) after which a destination is
considered inactive.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>includeBodyForAdvisory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Includes the body of the
original message that triggered the advisory as part of
the <strong><code>dataStructure</code></strong> field in the advisory
message (where applicable). Normally the message body is
cleared.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>maxBrowsePageSize</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>400</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The maximum number of messages to page in
from the store at one time for a browser.</p></td></tr><tr><td colspan="1"
rowspan="1" class="conflue
nceTd"><p><code>maxDestinations</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>-1</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>(v5.12) If <strong><code>0</code></strong> or
greater, sets the maximum number of destinations that can be created. This
parameter is intended to limit the number of hierarchical destinations that can
be created under a wildcard destination.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>maxPageSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>200</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The maximum number of messages
to page in from the store at one time. Increase this value to improve
performance for queue destination's that contain grouped messages that are
consumed by multiple concurrent consumers.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>memoryLimit</code></p></td><td
colspan="1" rowspan
="1" class="confluenceTd"><p><code>n/a</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The memory limit (in bytes) of the
destination's cursor.</p><p>This memory limit is subordinate to the system
level memory limit, as specified by the <a shape="rect"
href="producer-flow-control.html"><code><systemUsage>/<memoryUsage></code></a>
<span class="confluence-link">attribute</span>. There is no default for this
value; it simply acts as a child to the overall broker memory until the broker
memory is exhausted.</p><p><strong>Note</strong>: when this limit is specified
the destination's <strong><code>cursorMemoryHighWaterMark</code></strong>
will be applied against it and not
the <strong><code><systemUsage>/><memoryUsage></code></strong>
memory limit.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>minimumMessageSize</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>1024</code></p><
/td><td colspan="1" rowspan="1" class="confluenceTd"><p>For non-serialized
messages (embedded broker) - the assumed size of the message used for memory
usage calculation. Serialized messages use the serialized size as the basis for
the memory calculation.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>prioritizedMessages</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Persist message priority
information.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>producerFlowControl</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If
<strong><code>true</code></strong> the broker will throttle (flow-control) the
producer. Throttling is achieved either by withholding the producer's ACK or by
raising a <strong><code>javax.jms.ResourceAllocationExc
eption</code></strong> (that's propagated back to the client) when local
resources e.g., memory and/or storage, have been
exhausted.</p><p>If <strong><code>false</code></strong> excess messages
will be written to the message store to prevent memory exhaustion. However,
when the message store reaches capacity the producer will be throttled until
resources are freed.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>slowConsumerStrategy</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>null</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the strategy for handling
slow consumers. See <a shape="rect" class="external-link"
href="https://github.com/apache/activemq/blob/master/activemq-broker/src/main/java/org/apache/activemq/broker/region/policy/AbortSlowConsumerStrategy.java";
rel="nofollow">AbortSlowConsumerStrategy.</a></p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>storeUsageHighWat
erMark</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>100</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The percentage (%) threshold of
the <strong><code><systemUsage>/<storeUsage></code></strong>
store limit which when exceeded causes a send to block.</p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>useCache</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>
persistent messages are cached for fast retrieval from
store.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><span><code>usePrefetchExtension</code><br
clear="none"></span></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>true</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The prefetch extension is used when a message is
delivered but not ACK
'ed, such that the broker can dispatch another message, e.g.,
<code>prefetch == 0</code>, the idea being that there will always be prefetch
number of messages pending. It also allows a transaction batch to exceed the
prefetch value.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><code><span style="color: rgb(0,0,0);">sendFailIfNoSpace
</span></code></td><td colspan="1" rowspan="1" class="confluenceTd"><code><span
style="color: rgb(0,0,0);">false</span></code></td><td colspan="1" rowspan="1"
class="confluenceTd"><span style="color: rgb(0,0,0);">(v5.16.0) If true, will
cause a send to fail with a javax.jms.ResourceAllocationException when the
destination has reached is resource limits (memory or
storage)</span></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><code><span style="color:
rgb(0,0,0);">sendFailIfNoSpaceAfterTimeout</span></code></td><td colspan="1"
rowspan="1" class="confluenceTd"><code>0</code></td><td colspan="1" rowspan="1"
clas
s="confluenceTd"><span style="color: rgb(0,0,0);">(v5.16.0) if > 0, will
cause a send to fail with a javax.jms.ResourceAllocationException when the
destination resource limits (memory or storage) remain exhausted for the
configured duration in
milliseconds</span></td></tr></tbody></table></div><p>Additional properties for
a Queue</p><div class="table-wrap"><table
class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1"
class="confluenceTh"><p>Queue Only Property</p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p>Default Value</p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1"
rowspan="1"
class="confluenceTd"><p><code>allConsumersExclusiveByDefault</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p>When <strong><code>true</code></strong> all
consumers will be exclusive. See <a shape="rect" href="nms/activemq-exclus
ive-consumers.html">ActiveMQ Exclusive Consumers</a></p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>cursorMemoryHighWaterMark</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>70</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The percentage (%) threshold
applied either to
the <strong><code><systemUsage>/<memoryUsage></code></strong>
or the destination's <strong><code>memoryLimit</code></strong> (when
defined) which when exceeded will cause the destination's cursor to either
block or write to disk.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>consumersBeforeDispatchStarts</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>0</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>When the first consumer
connects, wait for specified number of consumers before message dispatching
starts.</p></td></tr><tr><td colspan="1" rowspan="1" c
lass="confluenceTd"><p><code>expireMessagesPeriod</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>30000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The period (in ms) of checks
for message expiry on queued messages, value of 0
disables.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>lazyDispatch</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Only page in from store the number of
messages that can be dispatched at time.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><pre>maxExpirePageSize</pre></td><td
colspan="1" rowspan="1" class="confluenceTd"><pre>400</pre></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The maximum number of messages to page in
when periodically expiring messages.</p><p>Messages are paged in according to
this setting if the number of messages in memory pending dis
patch is less than this value, and there are messages in the store to page in.
Messages are expired during this paging step as they are brought into memory
from the store.</p><p>Once the paging process is completed, messages are
expired from the list of those that are in memory and pending dispatch, then
from the list of those that are in memory but not yet targeted at a
subscription.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>optimizedDispatch</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Don't use a separate thread for dispatching
from a Queue.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>persistJMSRedelivered</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>(v 5.10) If true, before a
persistent message is dispatched by the br
oker for the first time, the message is rewritten to reflect the possible
delivery.</p><p>This ensures the
message <strong><code>JMSRedelivered</code></strong> header is a reliable
indication of possible duplicate delivery.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>queuePrefetch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>n/a</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the prefetch for consumers
that are using the default value.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>strictOrderDispatch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p>If <strong><code>true</code></strong> queue will
not round robin consumers, but it'll use a single one until its prefetch buffer
is full.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>timeBefore
DispatchStarts</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>0</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>When the first consumer connects, wait for specified
time (in ms) before message dispatching starts.</p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>useConsumerPriority</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Use the priority of a consumer
when dispatching messages from a
Queue.</p></td></tr></tbody></table></div><p>Additional properties for a
Topic</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th
colspan="1" rowspan="1" class="confluenceTh"><p>Topic Only Property</p></th><th
colspan="1" rowspan="1" class="confluenceTh"><p>Default Value</p></th><th
colspan="1" rowspan="1"
class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p>
<code>advisoryForDiscardingMessages</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Send an advisory when a message is discarded from a non
durable subscription.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>cursorMemoryHighWaterMark</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>70</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The percentage (%) threshold
applied to
the <strong><code><systemUsage>/<memoryUsage></code></strong>
which when exceeded will cause the destination's cursor to either block or
write to disk.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><span style="color:
rgb(0,0,0);"><code>alwaysRetroactive</code><br clear="none"></span></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confl
uenceTd"><p>Makes all subscribers retroactive negating the need to modify the
clients to enable this feature.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>durableTopicPrefetch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>n/a</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the prefetch for durable
topic consumers that are using the default value.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><span style="color:
rgb(0,0,0);"><code>expireMessagesPeriod</code><br
clear="none"></span></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>30000</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The interval (in ms) between message expiration checks
on inactive durable subscribers.</p><p><strong>Note</strong>: set to
<strong><code>0</code></strong> to disable message expiration
checking.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><co
de>topicPrefetch</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>n/a</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Sets the prefetch for topic consumers that are using
the default value.</p></td></tr></tbody></table></div><p><span
style="line-height: 1.4285715;">The following are examples of different
policies that can be customized on a per destination
basis:</span></p><ul><li><a shape="rect" href="dispatch-policies.html">Dispatch
Policies</a></li></ul><p> </p></div>
+<div class="wiki-content maincontent"><p>We support a number of different
policies which can be attached to individual destinations (queues, topics) or
to wildcards of queue/topic hierarchies. This makes it easy to configure how
different regions of the JMS destination space are handled.</p><p>The
properties you can set on a Destination are as follows:</p><div
class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1"
rowspan="1" class="confluenceTh"><p>Common Property</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Default Value</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForConsumed</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message when a
message is consumed by a client.</p></td></tr><tr><td colspan="1" rowspan="1"
class="c
onfluenceTd"><p><code>advisoryForDelivery</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Send an advisory message when a message is
sent to a client.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForFastProducers</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message if a
producer is deemed fast.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryForSlowConsumers</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Send an advisory message if a
consumer is deemed slow.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>advisoryWhenFull</code></p></td><td colspan="1"
rowspan="1" class="conf
luenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Send an advisory message when a limit (memory, store,
temp disk) is full.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>enableAudit</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td colspan="1"
rowspan="1"
class="confluenceTd"><p>When <strong><code>true</code></strong> the broker
will track duplicate messages. Duplicates can happen for non-persistent
messages during failover.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>gcInactiveDestinations</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Garbage collect inactive
destinations.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>inactiveTimoutBeforeGC</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd">
<p><code>5000</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The timeout (in ms) after which a destination is
considered inactive.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>includeBodyForAdvisory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Includes the body of the
original message that triggered the advisory as part of
the <strong><code>dataStructure</code></strong> field in the advisory
message (where applicable). Normally the message body is
cleared.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>maxBrowsePageSize</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>400</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The maximum number of messages to page in
from the store at one time for a browser.</p></td></tr><tr><td colspan="1"
rowspan="1" class="conflue
nceTd"><p><code>maxDestinations</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>-1</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>(v5.12) If <strong><code>0</code></strong> or
greater, sets the maximum number of destinations that can be created. This
parameter is intended to limit the number of hierarchical destinations that can
be created under a wildcard destination.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>maxPageSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>200</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The maximum number of messages
to page in from the store at one time. Increase this value to improve
performance for queue destination's that contain grouped messages that are
consumed by multiple concurrent consumers.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>memoryLimit</code></p></td><td
colspan="1" rowspan
="1" class="confluenceTd"><p><code>n/a</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The memory limit (in bytes) of the
destination's cursor.</p><p>This memory limit is subordinate to the system
level memory limit, as specified by the <a shape="rect"
href="producer-flow-control.html"><code><systemUsage>/<memoryUsage></code></a>
<span class="confluence-link">attribute</span>. There is no default for this
value; it simply acts as a child to the overall broker memory until the broker
memory is exhausted.</p><p><strong>Note</strong>: when this limit is specified
the destination's <strong><code>cursorMemoryHighWaterMark</code></strong>
will be applied against it and not
the <strong><code><systemUsage>/><memoryUsage></code></strong>
memory limit.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>minimumMessageSize</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>1024</code></p><
/td><td colspan="1" rowspan="1" class="confluenceTd"><p>For non-serialized
messages (embedded broker) - the assumed size of the message used for memory
usage calculation. Serialized messages use the serialized size as the basis for
the memory calculation.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>prioritizedMessages</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Persist message priority
information.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>producerFlowControl</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If
<strong><code>true</code></strong> the broker will throttle (flow-control) the
producer. Throttling is achieved either by withholding the producer's ACK or by
raising a <strong><code>javax.jms.ResourceAllocationExc
eption</code></strong> (that's propagated back to the client) when local
resources e.g., memory and/or storage, have been
exhausted.</p><p>If <strong><code>false</code></strong> excess messages
will be written to the message store to prevent memory exhaustion. However,
when the message store reaches capacity the producer will be throttled until
resources are freed.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>slowConsumerStrategy</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>null</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the strategy for handling
slow consumers. See <a shape="rect" class="external-link"
href="https://github.com/apache/activemq/blob/master/activemq-broker/src/main/java/org/apache/activemq/broker/region/policy/AbortSlowConsumerStrategy.java";
rel="nofollow">AbortSlowConsumerStrategy.</a></p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>storeUsageHighWat
erMark</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>100</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The percentage (%) threshold of
the <strong><code><systemUsage>/<storeUsage></code></strong>
store limit which when exceeded causes a send to block.</p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>useCache</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>
persistent messages are cached for fast retrieval from
store.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><span><code>usePrefetchExtension</code><br
clear="none"></span></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>true</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The prefetch extension is used when a message is
delivered but not ACK
'ed, such that the broker can dispatch another message, e.g.,
<code>prefetch == 0</code>, the idea being that there will always be prefetch
number of messages pending. It also allows a transaction batch to exceed the
prefetch value.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><code><span style="color: rgb(0,0,0);">sendFailIfNoSpace
</span></code></td><td colspan="1" rowspan="1" class="confluenceTd"><code><span
style="color: rgb(0,0,0);">false</span></code></td><td colspan="1" rowspan="1"
class="confluenceTd"><span style="color: rgb(0,0,0);">(v5.16.0) If true, will
cause a send to fail with a javax.jms.ResourceAllocationException when the
destination has reached is resource limits (memory or
storage)</span></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><code><span style="color:
rgb(0,0,0);">sendFailIfNoSpaceAfterTimeout</span></code></td><td colspan="1"
rowspan="1" class="confluenceTd"><code>0</code></td><td colspan="1" rowspan="1"
clas
s="confluenceTd"><span style="color: rgb(0,0,0);">(v5.16.0) if > 0, will
cause a send to fail with a javax.jms.ResourceAllocationException when the
destination resource limits (memory or storage) remain exhausted for the
configured duration in
milliseconds</span></td></tr></tbody></table></div><p>Additional properties for
a Queue</p><div class="table-wrap"><table
class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1"
class="confluenceTh"><p>Queue Only Property</p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p>Default Value</p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1"
rowspan="1"
class="confluenceTd"><p><code>allConsumersExclusiveByDefault</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p>When <strong><code>true</code></strong> all
consumers will be exclusive. See <a shape="rect" href="nms/activemq-exclus
ive-consumers.html">ActiveMQ Exclusive Consumers</a></p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>cursorMemoryHighWaterMark</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>70</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The percentage (%) threshold
applied either to
the <strong><code><systemUsage>/<memoryUsage></code></strong>
or the destination's <strong><code>memoryLimit</code></strong> (when
defined) which when exceeded will cause the destination's cursor to either
block or write to disk.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>consumersBeforeDispatchStarts</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>0</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>When the first consumer
connects, wait for specified number of consumers before message dispatching
starts.</p></td></tr><tr><td colspan="1" rowspan="1" c
lass="confluenceTd"><p><code>expireMessagesPeriod</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>30000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The period (in ms) of checks
for message expiry on queued messages, value of 0
disables.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>lazyDispatch</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Only page in from store the number of
messages that can be dispatched at time.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><pre>maxExpirePageSize</pre></td><td
colspan="1" rowspan="1" class="confluenceTd"><pre>400</pre></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>The maximum number of messages to page in
when periodically expiring messages.</p><p>Messages are paged in according to
this setting if the number of messages in memory pending dis
patch is less than this value, and there are messages in the store to page in.
Messages are expired during this paging step as they are brought into memory
from the store.</p><p>Once the paging process is completed, messages are
expired from the list of those that are in memory and pending dispatch, then
from the list of those that are in memory but not yet targeted at a
subscription.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>optimizedDispatch</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p>Don't use a separate thread for dispatching
from a Queue.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>persistJMSRedelivered</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>(v 5.10) If true, before a
persistent message is dispatched by the br
oker for the first time, the message is rewritten to reflect the possible
delivery.</p><p>This ensures the
message <strong><code>JMSRedelivered</code></strong> header is a reliable
indication of possible duplicate delivery.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>queuePrefetch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>n/a</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the prefetch for consumers
that are using the default value.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>strictOrderDispatch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p>If <strong><code>true</code></strong> queue will
not round robin consumers, but it'll use a single one until its prefetch buffer
is full.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>timeBefore
DispatchStarts</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>0</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>When the first consumer connects, wait for specified
time (in ms) before message dispatching starts.</p></td></tr><tr><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>useConsumerPriority</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Use the priority of a consumer
when dispatching messages from a
Queue.</p></td></tr></tbody></table></div><p>Additional properties for a
Topic</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th
colspan="1" rowspan="1" class="confluenceTh"><p>Topic Only Property</p></th><th
colspan="1" rowspan="1" class="confluenceTh"><p>Default Value</p></th><th
colspan="1" rowspan="1"
class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p>
<code>advisoryForDiscardingMessages</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Send an advisory when a message is discarded from a non
durable subscription.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>cursorMemoryHighWaterMark</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>70</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The percentage (%) threshold
applied to
the <strong><code><systemUsage>/<memoryUsage></code></strong>
which when exceeded will cause the destination's cursor to either block or
write to disk.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><span style="color:
rgb(0,0,0);"><code>alwaysRetroactive</code><br clear="none"></span></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confl
uenceTd"><p>Makes all subscribers retroactive negating the need to modify the
clients to enable this feature.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>durableTopicPrefetch</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>n/a</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Sets the prefetch for durable
topic consumers that are using the default value.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><span style="color:
rgb(0,0,0);"><code>expireMessagesPeriod</code><br
clear="none"></span></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>30000</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>The interval (in ms) between message expiration checks
on inactive durable subscribers.</p><p><strong>Note</strong>: set to
<strong><code>0</code></strong> to disable message expiration
checking.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><co
de>topicPrefetch</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>n/a</code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p>Sets the prefetch for topic consumers that are using
the default value.</p></td></tr></tbody></table></div><p><span
style="line-height: 1.4285715;">The following are examples of different
policies that can be customized on a per destination
basis:</span></p><ul><li><a shape="rect" href="dispatch-policies.html">Dispatch
Policies</a></li></ul><pre> </pre><p>An example from the demos <a
shape="rect" class="external-link"
href="https://git-wip-us.apache.org/repos/asf?p=activemq.git;a=blob;f=assembly/src/release/examples/conf/activemq-demo.xml;hb=HEAD";>https://git-wip-us.apache.org/repos/asf?p=activemq.git;a=blob;f=assembly/src/release/examples/conf/activemq-demo.xml;hb=HEAD</a>: </p><p><code
class="xml plain"><</code><code class="xml keyword">beans</code> <code
class="xml color1">xmlns</code><code class="xml pl
ain">=</code><code class="xml string">"<a shape="rect" class="external-link"
href="http://www.springframework.org/schema/beans";
rel="nofollow">http://www.springframework.org/schema/beans</a>"</code></p><div
class="line number2 index1 alt1"><code class="xml
spaces">       </code><code class="xml
color1">xmlns:amq</code><code class="xml plain">=</code><code class="xml
string">"<a shape="rect" class="external-link"
href="http://activemq.apache.org/schema/core";>http://activemq.apache.org/schema/core</a>"</code></div><div
class="line number3 index2 alt2"><code class="xml
spaces">       </code><code class="xml
color1">xmlns:xsi</code><code class="xml plain">=</code><code class="xml
string">"<a shape="rect" class="external-link"
href="http://www.w3.org/2001/XMLSchema-instance";
rel="nofollow">http://www.w3.org/2001/XMLSchema-instance</a>"</code></div><div
class="line number4 index3 alt1"><code class="xml spaces"> 
60;     </code><code class="xml
plain">xsi:schemaLocation="<a shape="rect" class="external-link"
href="http://www.springframework.org/schema/beans";
rel="nofollow">http://www.springframework.org/schema/beans</a> <a shape="rect"
class="external-link"
href="http://www.springframework.org/schema/beans/spring-beans-2.0.xsd";
rel="nofollow">http://www.springframework.org/schema/beans/spring-beans-2.0.xsd</a></code></div><div
class="line number5 index4 alt2"><code class="xml
spaces">                           </code><code
class="xml plain"><a shape="rect" class="external-link"
href="http://activemq.apache.org/schema/core";>http://activemq.apache.org/schema/core</a>
<a shape="rect" class="external-link"
href="http://activemq.apache.org/schema/core/activemq-core.xsd";>http://activemq.apache.org/schema/core/activemq-core.xsd</a>"></cod
e></div><div class="line number6 index5 alt1"> </div><div class="line
number7 index6 alt2"><code class="xml spaces">  </code><code
class="xml plain"><</code><code class="xml keyword">bean</code> <code
class="xml color1">class</code><code class="xml plain">=</code><code class="xml
string">"org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"</code><code
class="xml plain">/></code></div><div class="line number8 index7
alt1"> </div><div class="line number9 index8 alt2"><code class="xml
spaces">  </code><code class="xml plain"><</code><code class="xml
keyword">broker</code> <code class="xml color1">persistent</code><code
class="xml plain">=</code><code class="xml string">"false"</code> <code
class="xml color1">brokerName</code><code class="xml plain">=</code><code
class="xml string">"${brokername}"</code> <code class="xml
color1">xmlns</code><code class="xml plain">=</code><code class="xml
string">"<a shape="rect" class="external
-link"
href="http://activemq.apache.org/schema/core";>http://activemq.apache.org/schema/core</a>"</code><code
class="xml plain">></code></div><div class="line number10 index9
alt1"><code class="xml spaces">    </code><code class="xml
comments"><!--  lets define the dispatch policy --></code></div><div
class="line number11 index10 alt2"><code class="xml
spaces">    </code><code class="xml plain"><</code><code
class="xml keyword">destinationPolicy</code><code class="xml
plain">></code></div><div class="line number12 index11 alt1"><code
class="xml spaces">      </code><code class="xml
plain"><</code><code class="xml keyword">policyMap</code><code class="xml
plain">></code></div><div class="line number13 index12 alt2"><code
class="xml spaces">        </code><code
class="xml plain"><</code><code class="xml
keyword">policyEntries</code><code class="xml
plain">></code></div><div class="line number14 index13 alt1"><code
class="xml
spaces">          </code><code
class="xml plain"><</code><code class="xml keyword">policyEntry</code>
<code class="xml plain">topic="FOO.>"></code></div><div class="line
number15 index14 alt2"><code class="xml
spaces">            </code><code
class="xml plain"><</code><code class="xml
keyword">dispatchPolicy</code><code class="xml plain">></code></div><div
class="line number16 index15 alt1"><code class="xml
spaces">              </code><code
class="xml plain"><</code><code class="xml
keyword">roundRobinDispatchPolicy</code> <code class="xml
plain">/></code></div><div class="line number17 index16 alt2"><code
class="xml
spaces">            </code><c
ode class="xml plain"></</code><code class="xml
keyword">dispatchPolicy</code><code class="xml plain">></code></div><div
class="line number18 index17 alt1"><code class="xml
spaces">            </code><code
class="xml plain"><</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><code class="xml
plain">></code></div><div class="line number19 index18 alt2"><code
class="xml
spaces">              </code><code
class="xml plain"><</code><code class="xml
keyword">lastImageSubscriptionRecoveryPolicy</code> <code class="xml
plain">/></code></div><div class="line number20 index19 alt1"><code
class="xml
spaces">            </code><code
class="xml plain"></</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><code class="xml
plain">></code></div><div class="li
ne number21 index20 alt2"><code class="xml
spaces">          </code><code
class="xml plain"></</code><code class="xml
keyword">policyEntry</code><code class="xml plain">></code></div><div
class="line number22 index21 alt1"><code class="xml
spaces">          </code> </div><div
class="line number23 index22 alt2"><code class="xml
spaces">          </code><code
class="xml plain"><</code><code class="xml keyword">policyEntry</code>
<code class="xml plain">topic="ORDERS.>"></code></div><div class="line
number24 index23 alt1"><code class="xml
spaces">            </code><code
class="xml plain"><</code><code class="xml
keyword">dispatchPolicy</code><code class="xml plain">></code></div><div
class="line number25 index24 alt2"><code class="xml spaces"> 
0;            </code><code
class="xml plain"><</code><code class="xml
keyword">strictOrderDispatchPolicy</code> <code class="xml
plain">/></code></div><div class="line number26 index25 alt1"><code
class="xml
spaces">            </code><code
class="xml plain"></</code><code class="xml
keyword">dispatchPolicy</code><code class="xml plain">></code></div><div
class="line number27 index26 alt2"> </div><div class="line number28
index27 alt1"><code class="xml
spaces">            </code><code
class="xml comments"><!--  1 minute's worth --></code></div><div
class="line number29 index28 alt2"><code class="xml
spaces">            </code><code
class="xml plain"><</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><
code class="xml plain">></code></div><div class="line number30 index29
alt1"><code class="xml
spaces">              </code><code
class="xml plain"><</code><code class="xml
keyword">timedSubscriptionRecoveryPolicy</code> <code class="xml
color1">recoverDuration</code><code class="xml plain">=</code><code class="xml
string">"60000"</code> <code class="xml plain">/></code></div><div
class="line number31 index30 alt2"><code class="xml
spaces">            </code><code
class="xml plain"></</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><code class="xml
plain">></code></div><div class="line number32 index31 alt1"><code
class="xml
spaces">          </code><code
class="xml plain"></</code><code class="xml
keyword">policyEntry</code><code class="xml plain">></code></div><div cl
ass="line number33 index32 alt2"><code class="xml
spaces">    </code> </div><div class="line number34
index33 alt1"><code class="xml
spaces">          </code><code
class="xml plain"><</code><code class="xml keyword">policyEntry</code>
<code class="xml plain">topic="PRICES.>"></code></div><div class="line
number35 index34 alt2"><code class="xml
spaces">            </code><code
class="xml comments"><!-- lets force old messages to be discarded for slow
consumers --></code></div><div class="line number36 index35 alt1"><code
class="xml
spaces">            </code><code
class="xml plain"><</code><code class="xml
keyword">pendingMessageLimitStrategy</code><code class="xml
plain">></code></div><div class="line number37 index36 alt2"><code
class="xml spaces">   
0;          </code><code
class="xml plain"><</code><code class="xml
keyword">constantPendingMessageLimitStrategy</code> <code class="xml
color1">limit</code><code class="xml plain">=</code><code class="xml
string">"10"</code><code class="xml plain">/></code></div><div class="line
number38 index37 alt1"><code class="xml
spaces">            </code><code
class="xml plain"></</code><code class="xml
keyword">pendingMessageLimitStrategy</code><code class="xml
plain">></code></div><div class="line number39 index38
alt2"> </div><div class="line number40 index39 alt1"><code class="xml
spaces">            </code><code
class="xml comments"><!--  10 seconds worth --></code></div><div
class="line number41 index40 alt2"><code class="xml
spaces">         
0;  </code><code class="xml plain"><</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><code class="xml
plain">></code></div><div class="line number42 index41 alt1"><code
class="xml
spaces">              </code><code
class="xml plain"><</code><code class="xml
keyword">timedSubscriptionRecoveryPolicy</code> <code class="xml
color1">recoverDuration</code><code class="xml plain">=</code><code class="xml
string">"10000"</code> <code class="xml plain">/></code></div><div
class="line number43 index42 alt2"><code class="xml
spaces">            </code><code
class="xml plain"></</code><code class="xml
keyword">subscriptionRecoveryPolicy</code><code class="xml
plain">></code></div><div class="line number44 index43 alt1"><code
class="xml
spaces">            </code>
 </div><div class="line number45 index44 alt2"><code class="xml
spaces">          </code><code
class="xml plain"></</code><code class="xml
keyword">policyEntry</code><code class="xml plain">></code></div><div
class="line number46 index45 alt1"><code class="xml
spaces">          </code><code
class="xml plain"><</code><code class="xml keyword">policyEntry</code>
<code class="xml color1">tempTopic</code><code class="xml plain">=</code><code
class="xml string">"true"</code> <code class="xml
color1">advisoryForConsumed</code><code class="xml plain">=</code><code
class="xml string">"true"</code> <code class="xml plain">/></code></div><div
class="line number47 index46 alt2"><code class="xml
spaces">          </code><code
class="xml plain"><</code><code class="xml keyword">policyEntry</code>
<code class="xml color1">tempQue
ue</code><code class="xml plain">=</code><code class="xml
string">"true"</code> <code class="xml color1">advisoryForConsumed</code><code
class="xml plain">=</code><code class="xml string">"true"</code> <code
class="xml plain">/></code></div><div class="line number48 index47
alt1"><code class="xml
spaces">        </code><code class="xml
plain"></</code><code class="xml keyword">policyEntries</code><code
class="xml plain">></code></div><div class="line number49 index48
alt2"><code class="xml spaces">      </code><code
class="xml plain"></</code><code class="xml keyword">policyMap</code><code
class="xml plain">></code></div><div class="line number50 index49
alt1"><code class="xml spaces">    </code><code class="xml
plain"></</code><code class="xml keyword">destinationPolicy</code><code
class="xml plain">></code></div><div class="line number51 index50
alt2"><code class="xml spa
ces">  </code><code class="xml plain"></</code><code class="xml
keyword">broker</code><code class="xml plain">></code></div><div class="line
number52 index51 alt1"><code class="xml plain"></</code><code class="xml
keyword">beans</code><code class="xml plain">></code></div></div>
</td>
<td valign="top">
<div class="navigation">
Modified: websites/production/activemq/content/virtual-destinations.html
==============================================================================
--- websites/production/activemq/content/virtual-destinations.html (original)
+++ websites/production/activemq/content/virtual-destinations.html Wed Oct 25
16:24:29 2017
@@ -71,46 +71,7 @@
<tbody>
<tr>
<td valign="top" width="100%">
-<div class="wiki-content maincontent"><p><em>Virtual Destinations</em> allow
us to create logical destinations that clients can use to produce and consume
from but which map onto one or more <em>physical destinations</em>. It allows
us to provide more flexible loosely coupled messaging configurations.</p><h2
id="VirtualDestinations-VirtualTopics">Virtual Topics</h2><p>The idea behind
<em>publish subscribe</em> is a great one. Allow producers to be decoupled from
consumers so that they do not even know how many consumers are interested in
the messages they publish. The JMS specification defines support for durable
topics however they have limitations as we will describe...</p><h3
id="VirtualDestinations-ThelimitationsofJMSdurabletopics">The limitations of
JMS durable topics</h3><p>A JMS durable subscriber MessageConsumer is created
with a unique JMS clientID and durable subscriber name. To be JMS compliant
only one JMS connection can be active at any point in time for one JMS clientI
D, and only one consumer can be active for a clientID and subscriber name.
i.e., only <strong>one</strong> thread can be actively consuming from a given
logical topic subscriber. This means we cannot implement</p><ul><li>load
balancing of messages.</li><li>fast failover of the subscriber if that one
process running that one consumer thread dies.</li></ul><p>Now <em>queue</em>
semantics in JMS offer the ability to load balance work across a number of
consumers in a reliable way - allowing many threads, processes and machines to
be used to process messages. Then we have sophisticated sticky load balancing
techniques like <a shape="rect" href="message-groups.html">Message Groups</a>
to load balance and parallelise work while maintaining ordering.</p><p>Another
added benefit of having physical queues for each logical topic subscriber is we
can them monitor the queue depths via <a shape="rect" href="jmx.html">JMX</a>
to monitor system performance together with being able to browse these
physical queues.</p><h3
id="VirtualDestinations-VirtualTopicstotherescue">Virtual Topics to the
rescue</h3><p>The idea behind virtual topics is that producers send to a topic
in the usual JMS way. Consumers can continue to use the Topic semantics in the
JMS specification. However if the topic is virtual, consumer can consume from a
physical queue for a logical topic subscription, allowing many consumers to be
running on many machines & threads to load balance the load.</p><p>E.g.,
let's say we have a topic called <strong>VirtualTopic.Orders</strong>. (Where
the prefix VirtualTopic. indicates its a virtual topic). And we logically want
to send orders to systems A and B. Now with regular durable topics we'd create
a JMS consumer for clientID_A and "A" along with clientID_B and "B".</p><p>With
virtual topics we can just go right ahead and consume to queue
<strong>Consumer.A.VirtualTopic.Orders</strong> to be a consumer for system A
or consume to <strong>Consumer.B.VirtualTopic.Orde
rs</strong> to be a consumer for system B.</p><p>We can now have a pool of
consumers for each system which then compete for messages for systems A or B
such that all the messages for system A are processed exactly once and
similarly for system B.</p><h3
id="VirtualDestinations-Customizingtheout-of-the-boxdefaults">Customizing the
out-of-the-box defaults</h3><p>The out-of-the-box defaults are described above.
Namely that the only virtual topics available must be within the
<strong>VirtualTopic.></strong> namespace and that the consumer queues are
named <strong>Consumer.*.VirtualTopic.></strong>.</p><p>You can configure
this to use whatever naming convention you wish. The following <a shape="rect"
class="external-link"
href="https://svn.apache.org/repos/asf/incubator/activemq/trunk/activemq-unit-tests/src/test/resources/org/apache/activemq/broker/virtual/global-virtual-topics.xml";>example</a>
shows how to make all topics virtual topics. The example below is using the
name <stron
g>></strong> to indicate 'match all topics'. You could use this wildcard to
apply different virtual topic policies in different hierarchies.</p><parameter
ac:name="">xml</parameter><plain-text-body><destinationInterceptors>
- <virtualDestinationInterceptor>
- <virtualDestinations>
- <virtualTopic name=">" prefix="VirtualTopicConsumers.*."
selectorAware="false"/>
- </virtualDestinations>
- </virtualDestinationInterceptor>
-</destinationInterceptors></plain-text-body><p>Note that making a topic
virtual does add a small CPU overhead when sending messages to the topic but it
is fairly small.</p><div class="table-wrap"><table
class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1"
class="confluenceTh">Option</th><th colspan="1" rowspan="1"
class="confluenceTh">Default</th><th colspan="1" rowspan="1"
class="confluenceTh">Description</th></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd">selectorAware</td><td colspan="1" rowspan="1"
class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">only messages that match one of the existing subscribers
are actually dispatched. Using this option prevents the build up of unmatched
messages when selectors are used by exclusive consumers</td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd">local</td><td colspan="1"
rowspan="1" class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, d
on't fan out messages that were received over a network</td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd">concurrentSend</td><td colspan="1"
rowspan="1" class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, use an executor to fanout such that sends occur
in parallel. This allows the journal to batch writes which will reduce disk io
(5.12)</td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd">transactedSend</td><td colspan="1" rowspan="1"
class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, use a transaction for fanout sends such that
there is a single disk sync. A local broker transaction will be created if
there is no client transaction
(5.13)</td></tr></tbody></table></div><p> </p><h2
id="VirtualDestinations-CompositeDestinations">Composite
Destinations</h2><p>Composite Destinations allow for one-to-many relationships
on individual destinations; the main use case is for <em>composit
e queues</em>. For example when a message is sent to queue A you may want to
forward it also to queues B and C and topic D. Composite destinations are then
a mapping from a virtual destination to a collection of other physical
destinations. In this case the mapping is broker side and the client is unaware
of the mapping between the destinations. This is different from client side <a
shape="rect" href="composite-destinations.html">Composite Destinations</a>
where the client uses a URL notation to specify the actual physical
destinations that a message must be sent to.</p><p>The following <a
shape="rect" class="external-link"
href="http://svn.apache.org/repos/asf/incubator/activemq/trunk/activemq-unit-tests/src/test/resources/org/apache/activemq/broker/virtual/composite-queue.xml";>example</a>
shows how to set up a <strong><compositeQueue/></strong> element in the
XML configuration so that when a message is sent to <code>MY.QUEUE</code> then
it is really forwarded to the physical
queue <code>FOO</code> and the topic <code>BAR</code>.</p><parameter
ac:name="">xml</parameter><plain-text-body><destinationInterceptors>
- <virtualDestinationInterceptor>
- <virtualDestinations>
- <compositeQueue name="MY.QUEUE">
- <forwardTo>
- <queue physicalName="FOO" />
- <topic physicalName="BAR" />
- </forwardTo>
- </compositeQueue>
- </virtualDestinations>
- </virtualDestinationInterceptor>
-</destinationInterceptors></plain-text-body><p>By default, subscribers
cannot consume messages directly from a composite queue or topic - it is a
logical construct only. Given the configuration above, subscribers can only
consume messages from <code>FOO</code> and <code>BAR</code>; but not
<code>MY.QUEUE</code>.</p><p>This behaviour can be altered to implement use
cases such as watching a queue by sending the same messages to a notification
topic (wire tapping), by setting the optionally set <code>forwardOnly</code>
attribute to false.</p><parameter
ac:name="">xml</parameter><plain-text-body><compositeQueue
name="IncomingOrders" forwardOnly="false">
- <forwardTo>
- <topic physicalName="Notifications" />
- </forwardTo>
-</compositeQueue></plain-text-body><p>Messages sent to
<code>IncomingOrders</code> will all be copied and forwarded to
<code>Notifications</code>, before being placed on the physical
<code>IncomingOrders</code> queue for consumption by subscribers.</p><p>Where
the <code>forwardOnly</code> attribute is not defined or is set to
<code>true</code>, there is no logical difference between a
<code>compositeQueue</code> and a <code>compositeTopic</code> - they can be
used interchangeably. It is only when a composite destination is made physical
through the use of <code>forwardOnly</code> that the choice of
<code>compositeTopic</code>/<code>compositeQueue</code> has an impact on
behavior.</p><h3 id="VirtualDestinations-Usingfiltereddestinations">Using
filtered destinations</h3><p>From Apache ActiveMQ <strong>4.2</strong> onwards
you can now use selectors to define virtual destinations.</p><p>You may wish to
create a virtual destination which forwards messages to multiple destinations b
ut applying a selector first to decide if the message really does have to go
to a particular destination.</p><p>The following example shows how a message
sent to the virtual destination <strong>MY.QUEUE</strong> will be forwarded to
<strong>FOO</strong> and <strong>BAR</strong> if the selectors
match</p><parameter
ac:name="">xml</parameter><plain-text-body><destinationInterceptors>
- <virtualDestinationInterceptor>
- <virtualDestinations>
- <compositeQueue name="MY.QUEUE">
- <forwardTo>
- <filteredDestination selector="odd = 'yes'"
queue="FOO"/>
- <filteredDestination selector="i = 5" topic="BAR"/>
- </forwardTo>
- </compositeQueue>
- </virtualDestinations>
- </virtualDestinationInterceptor>
-</destinationInterceptors></plain-text-body><h2
id="VirtualDestinations-AvoidingDuplicateMessageinaNetworkofBrokers">Avoiding
Duplicate Message in a Network of Brokers</h2><p>You have to make sure that the
messages sent to the <strong>Consumer.*.VirtualTopic.></strong> destination
are not forwarded when you're using both queue-based and non-queue based
subscribers to the virtual topic (that is, if you have normal topic subscribers
to the virtual topic). If you use Virtual Topics in a network of brokers, it is
likely you will get duplicate messages if you use the default network
configuration. This is because a network node will not only forward message
sent to the virtual topic, but also the associated physical queues. To fix
this, you should disable forwarding messages on the associated physical
queues.</p><p>Here is an example of how to do that:</p><parameter
ac:name="">xml</parameter><plain-text-body> <networkConnectors>
- <networkConnector uri="static://(tcp://localhost:61617)">
- <excludedDestinations>
- <queue physicalName="Consumer.*.VirtualTopic.>"/>
- </excludedDestinations>
- </networkConnector>
- </networkConnectors>
-</plain-text-body></div>
+<div class="wiki-content maincontent"><p><em>Virtual Destinations</em> allow
us to create logical destinations that clients can use to produce and consume
from but which map onto one or more <em>physical destinations</em>. It allows
us to provide more flexible loosely coupled messaging configurations.</p><h2
id="VirtualDestinations-VirtualTopics">Virtual Topics</h2><p>The idea behind
<em>publish subscribe</em> is a great one. Allow producers to be decoupled from
consumers so that they do not even know how many consumers are interested in
the messages they publish. The JMS specification defines support for durable
topics however they have limitations as we will describe...</p><h3
id="VirtualDestinations-ThelimitationsofJMSdurabletopics">The limitations of
JMS durable topics</h3><p>A JMS durable subscriber MessageConsumer is created
with a unique JMS clientID and durable subscriber name. To be JMS compliant
only one JMS connection can be active at any point in time for one JMS clientI
D, and only one consumer can be active for a clientID and subscriber name.
i.e., only <strong>one</strong> thread can be actively consuming from a given
logical topic subscriber. This means we cannot implement</p><ul><li>load
balancing of messages.</li><li>fast failover of the subscriber if that one
process running that one consumer thread dies.</li></ul><p>Now <em>queue</em>
semantics in JMS offer the ability to load balance work across a number of
consumers in a reliable way - allowing many threads, processes and machines to
be used to process messages. Then we have sophisticated sticky load balancing
techniques like <a shape="rect" href="message-groups.html">Message Groups</a>
to load balance and parallelise work while maintaining ordering.</p><p>Another
added benefit of having physical queues for each logical topic subscriber is we
can them monitor the queue depths via <a shape="rect" href="jmx.html">JMX</a>
to monitor system performance together with being able to browse these
physical queues.</p><h3
id="VirtualDestinations-VirtualTopicstotherescue">Virtual Topics to the
rescue</h3><p>The idea behind virtual topics is that producers send to a topic
in the usual JMS way. Consumers can continue to use the Topic semantics in the
JMS specification. However if the topic is virtual, consumer can consume from a
physical queue for a logical topic subscription, allowing many consumers to be
running on many machines & threads to load balance the load.</p><p>E.g.,
let's say we have a topic called <strong>VirtualTopic.Orders</strong>. (Where
the prefix VirtualTopic. indicates its a virtual topic). And we logically want
to send orders to systems A and B. Now with regular durable topics we'd create
a JMS consumer for clientID_A and "A" along with clientID_B and "B".</p><p>With
virtual topics we can just go right ahead and consume to queue
<strong>Consumer.A.VirtualTopic.Orders</strong> to be a consumer for system A
or consume to <strong>Consumer.B.VirtualTopic.Orde
rs</strong> to be a consumer for system B.</p><p>We can now have a pool of
consumers for each system which then compete for messages for systems A or B
such that all the messages for system A are processed exactly once and
similarly for system B.</p><h3
id="VirtualDestinations-Customizingtheout-of-the-boxdefaults">Customizing the
out-of-the-box defaults</h3><p>The out-of-the-box defaults are described above.
Namely that the only virtual topics available must be within the
<strong>VirtualTopic.></strong> namespace and that the consumer queues are
named <strong>Consumer.*.VirtualTopic.></strong>.</p><p>You can configure
this to use whatever naming convention you wish. The following <a shape="rect"
class="external-link"
href="https://svn.apache.org/repos/asf/incubator/activemq/trunk/activemq-unit-tests/src/test/resources/org/apache/activemq/broker/virtual/global-virtual-topics.xml";>example</a>
shows how to make all topics virtual topics. The example below is using the
name <stron
g>></strong> to indicate 'match all topics'. You could use this wildcard to
apply different virtual topic policies in different hierarchies.</p><pre><span
style="color: rgb(0,0,0);"><destinationInterceptors>
</span></pre><pre><span style="color: rgb(0,0,0);">
<virtualDestinationInterceptor> </span></pre><pre><span style="color:
rgb(0,0,0);"> <virtualDestinations> </span></pre><pre><span style="color:
rgb(0,0,0);"> <virtualTopic name=">" prefix="VirtualTopicConsumers.*."
selectorAware="false"/> </span> </pre><pre>
</virtualDestinations></pre><pre><span style="color: rgb(0,0,0);">
</virtualDestinationInterceptor> </span></pre><pre><span style="color:
rgb(0,0,0);"></destinationInterceptors></span></pre><p> </p><p>Note
that making a topic virtual does add a small CPU overhead when sending messages
to the topic but it is fairly small.</p><div class="table-wrap"><table
class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" c
lass="confluenceTh">Option</th><th colspan="1" rowspan="1"
class="confluenceTh">Default</th><th colspan="1" rowspan="1"
class="confluenceTh">Description</th></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd">selectorAware</td><td colspan="1" rowspan="1"
class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">only messages that match one of the existing subscribers
are actually dispatched. Using this option prevents the build up of unmatched
messages when selectors are used by exclusive consumers</td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd">local</td><td colspan="1"
rowspan="1" class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, don't fan out messages that were received over
a network</td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd">concurrentSend</td><td colspan="1" rowspan="1"
class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, use an executor t
o fanout such that sends occur in parallel. This allows the journal to batch
writes which will reduce disk io (5.12)</td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd">transactedSend</td><td colspan="1" rowspan="1"
class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, use a transaction for fanout sends such that
there is a single disk sync. A local broker transaction will be created if
there is no client transaction (5.13)</td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><span>dropOnResourceLimit</span></td><td colspan="1"
rowspan="1" class="confluenceTd">false</td><td colspan="1" rowspan="1"
class="confluenceTd">when true, ignore any ResourceAllocationException thrown
during fanout (see: sendFailIfNoSpace policy entry)
(5.16)</td></tr></tbody></table></div><p> </p><h2
id="VirtualDestinations-CompositeDestinations">Composite
Destinations</h2><p>Composite Destinations allow for one-to-many relationships
on individual d
estinations; the main use case is for <em>composite queues</em>. For example
when a message is sent to queue A you may want to forward it also to queues B
and C and topic D. Composite destinations are then a mapping from a virtual
destination to a collection of other physical destinations. In this case the
mapping is broker side and the client is unaware of the mapping between the
destinations. This is different from client side <a shape="rect"
href="composite-destinations.html">Composite Destinations</a> where the client
uses a URL notation to specify the actual physical destinations that a message
must be sent to.</p><p>The following <a shape="rect" class="external-link"
href="http://svn.apache.org/repos/asf/incubator/activemq/trunk/activemq-unit-tests/src/test/resources/org/apache/activemq/broker/virtual/composite-queue.xml";>example</a>
shows how to set up a <strong><compositeQueue/></strong> element in the
XML configuration so that when a message is sent to <code>MY.QUEUE<
/code> then it is really forwarded to the physical queue <code>FOO</code> and
the topic <code>BAR</code>.</p><pre><span style="color:
rgb(0,0,0);"><destinationInterceptors></span></pre><pre><span
style="color: rgb(0,0,0);"> <virtualDestinationInterceptor>
</span></pre><pre><span style="color: rgb(0,0,0);"> <virtualDestinations>
</span></pre><pre><span style="color: rgb(0,0,0);"> <compositeQueue
name="MY.QUEUE"></span></pre><pre><span style="color: rgb(0,0,0);">
<forwardTo></span></pre><pre><span style="color: rgb(0,0,0);"> <queue
physicalName="FOO" /> </span></pre><pre><span style="color: rgb(0,0,0);">
<topic physicalName="BAR" /></span></pre><pre><span style="color:
rgb(0,0,0);"> </forwardTo></span></pre><pre><span style="color:
rgb(0,0,0);"> </compositeQueue></span></pre><pre><span style="color:
rgb(0,0,0);"> </virtualDestinations></span></pre><pre><span style="color:
rgb(0,0,0);"> </virtualDestinationInterceptor></
span></pre><pre><span style="color:
rgb(0,0,0);"></destinationInterceptors></span></pre><p> </p><p>By
default, subscribers cannot consume messages directly from a composite queue or
topic - it is a logical construct only. Given the configuration above,
subscribers can only consume messages from <code>FOO</code> and
<code>BAR</code>; but not <code>MY.QUEUE</code>.</p><p>This behaviour can be
altered to implement use cases such as watching a queue by sending the same
messages to a notification topic (wire tapping), by setting the optionally set
<code>forwardOnly</code> attribute to false.</p><pre><compositeQueue
name="IncomingOrders" forwardOnly="false"> </pre><pre>
<forwardTo></pre><pre> <topic physicalName="Notifications"
/></pre><pre> </forwardTo></pre><pre>
</compositeQueue></pre><p> </p><p>Messages sent to
<code>IncomingOrders</code> will all be copied and forwarded to
<code>Notifications</code>, before being placed on the phys
ical <code>IncomingOrders</code> queue for consumption by
subscribers.</p><p>Where the <code>forwardOnly</code> attribute is not defined
or is set to <code>true</code>, there is no logical difference between a
<code>compositeQueue</code> and a <code>compositeTopic</code> - they can be
used interchangeably. It is only when a composite destination is made physical
through the use of <code>forwardOnly</code> that the choice of
<code>compositeTopic</code>/<code>compositeQueue</code> has an impact on
behavior.</p><h3 id="VirtualDestinations-Usingfiltereddestinations">Using
filtered destinations</h3><p>From Apache ActiveMQ <strong>4.2</strong> onwards
you can now use selectors to define virtual destinations.</p><p>You may wish to
create a virtual destination which forwards messages to multiple destinations
but applying a selector first to decide if the message really does have to go
to a particular destination.</p><p>The following example shows how a message
sent to the virtual destinatio
n <strong>MY.QUEUE</strong> will be forwarded to <strong>FOO</strong> and
<strong>BAR</strong> if the selectors
match</p><pre><destinationInterceptors>
<virtualDestinationInterceptor> <virtualDestinations> </pre><pre>
<compositeQueue name="MY.QUEUE"></pre><pre>
<forwardTo></pre><pre> <filteredDestination selector="odd = 'yes'"
queue="FOO"/></pre><pre> <filteredDestination selector="i = 5"
topic="BAR"/></pre><pre> </forwardTo></pre><pre>
</compositeQueue></pre><pre></virtualDestinations>
</virtualDestinationInterceptor>
</destinationInterceptors></pre><p> </p><h2
id="VirtualDestinations-AvoidingDuplicateMessageinaNetworkofBrokers">Avoiding
Duplicate Message in a Network of Brokers</h2><p>You have to make sure that the
messages sent to the <strong>Consumer.*.VirtualTopic.></strong> destination
are not forwarded when you're using both queue-based and non-queue based
subscribers to the virtu
al topic (that is, if you have normal topic subscribers to the virtual topic).
If you use Virtual Topics in a network of brokers, it is likely you will get
duplicate messages if you use the default network configuration. This is
because a network node will not only forward message sent to the virtual topic,
but also the associated physical queues. To fix this, you should disable
forwarding messages on the associated physical queues.</p><p>Here is an example
of how to do that:</p><pre><span style="color:
rgb(0,0,0);"><networkConnectors> <networkConnector uri="static://(<a
shape="rect" href="tcp://localhost:61617"
rel="nofollow">tcp://localhost:61617</a>)"></span></pre><pre><span
style="color: rgb(0,0,0);"> <excludedDestinations>
</span></pre><pre><span style="color: rgb(0,0,0);"> <queue
physicalName="Consumer.*.VirtualTopic.>"/> </span></pre><pre><span
style="color: rgb(0,0,0);"> </excludedDestinations>
</span></pre><pre><span style="color: rgb(0,0,0)
;"></networkConnector>
</networkConnectors></span></pre><p> </p></div>
</td>
<td valign="top">
<div class="navigation">
