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| Introduction |
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| <b>1.</b> |
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| Legal Notice |
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| <b>2.</b> |
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| Preface |
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| <b>3.</b> |
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| Project Info |
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| <b>4.</b> |
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| Messaging Concepts |
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| <b>5.</b> |
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| Architecture |
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| <b>6.</b> |
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| Using the Server |
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| <a href="./using-jms.html"> |
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| <b>7.</b> |
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| Using JMS |
| </a> |
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| <a href="./using-core.html"> |
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| <b>8.</b> |
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| Using Core |
| </a> |
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| </li> |
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| <li class="chapter " data-level="9" data-path="jms-core-mapping.html"> |
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| <a href="./jms-core-mapping.html"> |
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| <b>9.</b> |
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| Mapping JMS Concepts to the Core API |
| </a> |
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| </li> |
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| <li class="chapter " data-level="10" data-path="client-classpath.html"> |
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| <a href="./client-classpath.html"> |
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| <b>10.</b> |
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| The Client Classpath |
| </a> |
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| <b>11.</b> |
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| Examples |
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| <li class="chapter " data-level="12" data-path="wildcard-routing.html"> |
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| <a href="./wildcard-routing.html"> |
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| <b>12.</b> |
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| Routing Messages With Wild Cards |
| </a> |
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| </li> |
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| <li class="chapter " data-level="13" data-path="wildcard-syntax.html"> |
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| <a href="./wildcard-syntax.html"> |
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| <b>13.</b> |
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| Understanding the Apache ActiveMQ Artemis Wildcard Syntax |
| </a> |
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| </li> |
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| <li class="chapter " data-level="14" data-path="filter-expressions.html"> |
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| <a href="./filter-expressions.html"> |
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| <b>14.</b> |
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| Filter Expressions |
| </a> |
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| </li> |
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| <li class="chapter " data-level="15" data-path="persistence.html"> |
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| <a href="./persistence.html"> |
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| <b>15.</b> |
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| Persistence |
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| <li class="chapter " data-level="16" data-path="configuring-transports.html"> |
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| <a href="./configuring-transports.html"> |
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| <b>16.</b> |
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| Configuring Transports |
| </a> |
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| </li> |
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| <li class="chapter " data-level="17" data-path="connection-ttl.html"> |
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| <a href="./connection-ttl.html"> |
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| <b>17.</b> |
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| Detecting Dead Connections |
| </a> |
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| </li> |
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| <li class="chapter " data-level="18" data-path="slow-consumers.html"> |
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| <a href="./slow-consumers.html"> |
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| <b>18.</b> |
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| Detecting Slow Consumers |
| </a> |
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| </li> |
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| <li class="chapter " data-level="19" data-path="transaction-config.html"> |
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| <a href="./transaction-config.html"> |
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| <b>19.</b> |
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| Resource Manager Configuration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="20" data-path="flow-control.html"> |
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| <a href="./flow-control.html"> |
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| <b>20.</b> |
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| Flow Control |
| </a> |
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| </li> |
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| <li class="chapter " data-level="21" data-path="send-guarantees.html"> |
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| <a href="./send-guarantees.html"> |
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| <b>21.</b> |
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| Guarantees of sends and commits |
| </a> |
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| </li> |
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| <li class="chapter " data-level="22" data-path="undelivered-messages.html"> |
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| <a href="./undelivered-messages.html"> |
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| <b>22.</b> |
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| Message Redelivery and Undelivered Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="23" data-path="message-expiry.html"> |
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| <a href="./message-expiry.html"> |
| <i class="fa fa-check"></i> |
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| <b>23.</b> |
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| Message Expiry |
| </a> |
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| </li> |
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| <li class="chapter " data-level="24" data-path="large-messages.html"> |
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| <a href="./large-messages.html"> |
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| <b>24.</b> |
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| Large Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="25" data-path="paging.html"> |
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| <a href="./paging.html"> |
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| <b>25.</b> |
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| Paging |
| </a> |
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| </li> |
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| <li class="chapter " data-level="26" data-path="queue-attributes.html"> |
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| <a href="./queue-attributes.html"> |
| <i class="fa fa-check"></i> |
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| <b>26.</b> |
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| Queue Attributes |
| </a> |
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| </li> |
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| <li class="chapter " data-level="27" data-path="scheduled-messages.html"> |
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| <a href="./scheduled-messages.html"> |
| <i class="fa fa-check"></i> |
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| <b>27.</b> |
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| Scheduled Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="28" data-path="last-value-queues.html"> |
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| <a href="./last-value-queues.html"> |
| <i class="fa fa-check"></i> |
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| <b>28.</b> |
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| Last-Value Queues |
| </a> |
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| </li> |
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| <li class="chapter active" data-level="29" data-path="message-grouping.html"> |
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| <a href="./message-grouping.html"> |
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| <b>29.</b> |
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| Message Grouping |
| </a> |
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| </li> |
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| <li class="chapter " data-level="30" data-path="pre-acknowledge.html"> |
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| <a href="./pre-acknowledge.html"> |
| <i class="fa fa-check"></i> |
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| <b>30.</b> |
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| Extra Acknowledge Modes |
| </a> |
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| </li> |
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| <li class="chapter " data-level="31" data-path="management.html"> |
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| <a href="./management.html"> |
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| <b>31.</b> |
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| Management |
| </a> |
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| </li> |
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| <li class="chapter " data-level="32" data-path="security.html"> |
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| <a href="./security.html"> |
| <i class="fa fa-check"></i> |
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| <b>32.</b> |
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| Security |
| </a> |
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| </li> |
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| <li class="chapter " data-level="33" data-path="resource-limits.html"> |
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| <a href="./resource-limits.html"> |
| <i class="fa fa-check"></i> |
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| <b>33.</b> |
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| Resource Limits |
| </a> |
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| </li> |
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| <li class="chapter " data-level="34" data-path="jms-bridge.html"> |
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| <a href="./jms-bridge.html"> |
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| <b>34.</b> |
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| The JMS Bridge |
| </a> |
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| </li> |
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| <li class="chapter " data-level="35" data-path="client-reconnection.html"> |
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| <a href="./client-reconnection.html"> |
| <i class="fa fa-check"></i> |
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| <b>35.</b> |
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| Client Reconnection and Session Reattachment |
| </a> |
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| </li> |
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| <li class="chapter " data-level="36" data-path="diverts.html"> |
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| <a href="./diverts.html"> |
| <i class="fa fa-check"></i> |
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| <b>36.</b> |
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| Diverting and Splitting Message Flows |
| </a> |
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| </li> |
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| <li class="chapter " data-level="37" data-path="core-bridges.html"> |
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| <a href="./core-bridges.html"> |
| <i class="fa fa-check"></i> |
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| <b>37.</b> |
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| Core Bridges |
| </a> |
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| </li> |
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| <li class="chapter " data-level="38" data-path="duplicate-detection.html"> |
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| <a href="./duplicate-detection.html"> |
| <i class="fa fa-check"></i> |
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| <b>38.</b> |
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| Duplicate Message Detection |
| </a> |
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| </li> |
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| <li class="chapter " data-level="39" data-path="clusters.html"> |
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| <a href="./clusters.html"> |
| <i class="fa fa-check"></i> |
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| <b>39.</b> |
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| Clusters |
| </a> |
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| </li> |
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| <li class="chapter " data-level="40" data-path="ha.html"> |
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| <a href="./ha.html"> |
| <i class="fa fa-check"></i> |
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| <b>40.</b> |
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| High Availability and Failover |
| </a> |
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| </li> |
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| <li class="chapter " data-level="41" data-path="graceful-shutdown.html"> |
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| <a href="./graceful-shutdown.html"> |
| <i class="fa fa-check"></i> |
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| <b>41.</b> |
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| Graceful Server Shutdown |
| </a> |
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| </li> |
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| <li class="chapter " data-level="42" data-path="libaio.html"> |
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| <a href="./libaio.html"> |
| <i class="fa fa-check"></i> |
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| <b>42.</b> |
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| Libaio Native Libraries |
| </a> |
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| </li> |
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| <li class="chapter " data-level="43" data-path="thread-pooling.html"> |
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| <a href="./thread-pooling.html"> |
| <i class="fa fa-check"></i> |
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| <b>43.</b> |
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| Thread management |
| </a> |
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| </li> |
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| <li class="chapter " data-level="44" data-path="logging.html"> |
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| <a href="./logging.html"> |
| <i class="fa fa-check"></i> |
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| <b>44.</b> |
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| Logging |
| </a> |
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| </li> |
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| <li class="chapter " data-level="45" data-path="rest.html"> |
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| <a href="./rest.html"> |
| <i class="fa fa-check"></i> |
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| <b>45.</b> |
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| REST Interface |
| </a> |
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| </li> |
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| <li class="chapter " data-level="46" data-path="embedding-activemq.html"> |
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| <a href="./embedding-activemq.html"> |
| <i class="fa fa-check"></i> |
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| <b>46.</b> |
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| Embedding Apache ActiveMQ Artemis |
| </a> |
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| </li> |
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| <li class="chapter " data-level="47" data-path="spring-integration.html"> |
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| <a href="./spring-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>47.</b> |
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| Spring Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="48" data-path="aerogear-integration.html"> |
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| <a href="./aerogear-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>48.</b> |
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| AeroGear Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="49" data-path="vertx-integration.html"> |
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| <a href="./vertx-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>49.</b> |
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| VertX Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="50" data-path="intercepting-operations.html"> |
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| <a href="./intercepting-operations.html"> |
| <i class="fa fa-check"></i> |
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| <b>50.</b> |
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| Intercepting Operations |
| </a> |
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| </li> |
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| <li class="chapter " data-level="51" data-path="protocols-interoperability.html"> |
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| <a href="./protocols-interoperability.html"> |
| <i class="fa fa-check"></i> |
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| <b>51.</b> |
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| Protocols and Interoperability |
| </a> |
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| </li> |
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| <li class="chapter " data-level="52" data-path="tools.html"> |
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| <a href="./tools.html"> |
| <i class="fa fa-check"></i> |
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| <b>52.</b> |
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| Tools |
| </a> |
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| </li> |
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| <li class="chapter " data-level="53" data-path="maven-plugin.html"> |
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| <a href="./maven-plugin.html"> |
| <i class="fa fa-check"></i> |
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| <b>53.</b> |
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| Maven Plugin |
| </a> |
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| </li> |
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| <li class="chapter " data-level="54" data-path="perf-tuning.html"> |
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| <a href="./perf-tuning.html"> |
| <i class="fa fa-check"></i> |
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| <b>54.</b> |
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| Troubleshooting and Performance Tuning |
| </a> |
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| |
| |
| </li> |
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| <li class="chapter " data-level="55" data-path="configuration-index.html"> |
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| <a href="./configuration-index.html"> |
| <i class="fa fa-check"></i> |
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| <b>55.</b> |
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| Configuration Reference |
| </a> |
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| </li> |
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| <!-- Title --> |
| <h1> |
| <i class="fa fa-circle-o-notch fa-spin"></i> |
| <a href="./" >ActiveMQ Artemis Documentation</a> |
| </h1> |
| </div> |
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| |
| |
| <section class="normal" id="section-"> |
| |
| <h1 id="message-grouping">Message Grouping</h1> |
| <p>Message groups are sets of messages that have the following |
| characteristics:</p> |
| <ul> |
| <li><p>Messages in a message group share the same group id, i.e. they have |
| same group identifier property (<code>JMSXGroupID</code> for JMS, |
| <code>_AMQ_GROUP_ID</code> for Apache ActiveMQ Artemis Core API).</p> |
| </li> |
| <li><p>Messages in a message group are always consumed by the same |
| consumer, even if there are many consumers on a queue. They pin all |
| messages with the same group id to the same consumer. If that |
| consumer closes another consumer is chosen and will receive all |
| messages with the same group id.</p> |
| </li> |
| </ul> |
| <p>Message groups are useful when you want all messages for a certain value |
| of the property to be processed serially by the same consumer.</p> |
| <p>An example might be orders for a certain stock. You may want orders for |
| any particular stock to be processed serially by the same consumer. To |
| do this you can create a pool of consumers (perhaps one for each stock, |
| but less will work too), then set the stock name as the value of the |
| _AMQ_GROUP_ID property.</p> |
| <p>This will ensure that all messages for a particular stock will always be |
| processed by the same consumer.</p> |
| <blockquote> |
| <p><strong>Note</strong></p> |
| <p>Grouped messages can impact the concurrent processing of non-grouped |
| messages due to the underlying FIFO semantics of a queue. For example, |
| if there is a chunk of 100 grouped messages at the head of a queue |
| followed by 1,000 non-grouped messages then all the grouped messages |
| will need to be sent to the appropriate client (which is consuming |
| those grouped messages serially) before any of the non-grouped |
| messages can be consumed. The functional impact in this scenario is a |
| temporary suspension of concurrent message processing while all the |
| grouped messages are processed. This can be a performance bottleneck |
| so keep it in mind when determining the size of your message groups, |
| and consider whether or not you should isolate your grouped messages |
| from your non-grouped messages.</p> |
| </blockquote> |
| <h2 id="using-core-api">Using Core API</h2> |
| <p>The property name used to identify the message group is <code>"_AMQ_GROUP_ID"</code> |
| (or the constant <code>MessageImpl.HDR_GROUP_ID</code>). Alternatively, you can set |
| <code>autogroup</code> to true on the <code>SessionFactory</code> which will pick a random |
| unique id.</p> |
| <h2 id="using-jms">Using JMS</h2> |
| <p>The property name used to identify the message group is <code>JMSXGroupID</code>.</p> |
| <pre><code> // send 2 messages in the same group to ensure the same |
| // consumer will receive both |
| Message message = ... |
| message.setStringProperty("JMSXGroupID", "Group-0"); |
| producer.send(message); |
| |
| message = ... |
| message.setStringProperty("JMSXGroupID", "Group-0"); |
| producer.send(message); |
| </code></pre><p>Alternatively, you can set <code>autogroup</code> to true on the |
| <code>ActiveMQConnectonFactory</code> which will pick a random unique id. This can |
| also be set in the JNDI context environment, e.g. <code>jndi.properties</code>. |
| Here's a simple example using the "ConnectionFactory" connection factory |
| which is available in the context by default</p> |
| <pre><code>java.naming.factory.initial=org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory |
| connectionFactory.myConnectionFactory=tcp://localhost:61616?autoGroup=true |
| </code></pre><p>Alternatively you can set the group id via the connection factory. All |
| messages sent with producers created via this connection factory will |
| set the <code>JMSXGroupID</code> to the specified value on all messages sent. This |
| can also be set in the JNDI context environment, e.g. <code>jndi.properties</code>. |
| Here's a simple example using the "ConnectionFactory" connection factory |
| which is available in the context by default:</p> |
| <pre><code>java.naming.factory.initial=org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory |
| connectionFactory.myConnectionFactory=tcp://localhost:61616?roupID=Group-0 |
| </code></pre><h2 id="example">Example</h2> |
| <p>See the [examples](examples.md} chapter for an example which shows how message groups are configured and used with JMS and via a connection factory.</p> |
| <h2 id="clustered-grouping">Clustered Grouping</h2> |
| <p>Using message groups in a cluster is a bit more complex. This is because |
| messages with a particular group id can arrive on any node so each node |
| needs to know about which group id's are bound to which consumer on |
| which node. The consumer handling messages for a particular group id may |
| be on a different node of the cluster, so each node needs to know this |
| information so it can route the message correctly to the node which has |
| that consumer.</p> |
| <p>To solve this there is the notion of a grouping handler. Each node will |
| have its own grouping handler and when a messages is sent with a group |
| id assigned, the handlers will decide between them which route the |
| message should take.</p> |
| <p>There are 2 types of handlers; Local and Remote. Each cluster should |
| choose 1 node to have a local grouping handler and all the other nodes |
| should have remote handlers- it's the local handler that actually makes |
| the decision as to what route should be used, all the other remote |
| handlers converse with this. Here is a sample config for both types of |
| handler, this should be configured in the <em>broker.xml</em> |
| file.</p> |
| <pre><code><grouping-handler name="my-grouping-handler"> |
| <type>LOCAL</type> |
| <address>jms</address> |
| <timeout>5000</timeout> |
| </grouping-handler> |
| |
| <grouping-handler name="my-grouping-handler"> |
| <type>REMOTE</type> |
| <address>jms</address> |
| <timeout>5000</timeout> |
| </grouping-handler> |
| </code></pre><p>The <em>address</em> attribute refers to a <a href="#clusters.address">cluster connection and the address |
| it uses</a>, refer to the clustering section on how to |
| configure clusters. The <em>timeout</em> attribute referees to how long to wait |
| for a decision to be made, an exception will be thrown during the send |
| if this timeout is reached, this ensures that strict ordering is kept.</p> |
| <p>The decision as to where a message should be routed to is initially |
| proposed by the node that receives the message. The node will pick a |
| suitable route as per the normal clustered routing conditions, i.e. |
| round robin available queues, use a local queue first and choose a queue |
| that has a consumer. If the proposal is accepted by the grouping |
| handlers the node will route messages to this queue from that point on, |
| if rejected an alternative route will be offered and the node will again |
| route to that queue indefinitely. All other nodes will also route to the |
| queue chosen at proposal time. Once the message arrives at the queue |
| then normal single server message group semantics take over and the |
| message is pinned to a consumer on that queue.</p> |
| <p>You may have noticed that there is a single point of failure with the |
| single local handler. If this node crashes then no decisions will be |
| able to be made. Any messages sent will be not be delivered and an |
| exception thrown. To avoid this happening Local Handlers can be |
| replicated on another backup node. Simple create your back up node and |
| configure it with the same Local handler.</p> |
| <h2 id="clustered-grouping-best-practices">Clustered Grouping Best Practices</h2> |
| <p>Some best practices should be followed when using clustered grouping:</p> |
| <ol> |
| <li><p>Make sure your consumers are distributed evenly across the different |
| nodes if possible. This is only an issue if you are creating and |
| closing consumers regularly. Since messages are always routed to the |
| same queue once pinned, removing a consumer from this queue may |
| leave it with no consumers meaning the queue will just keep |
| receiving the messages. Avoid closing consumers or make sure that |
| you always have plenty of consumers, i.e., if you have 3 nodes have |
| 3 consumers.</p> |
| </li> |
| <li><p>Use durable queues if possible. If queues are removed once a group |
| is bound to it, then it is possible that other nodes may still try |
| to route messages to it. This can be avoided by making sure that the |
| queue is deleted by the session that is sending the messages. This |
| means that when the next message is sent it is sent to the node |
| where the queue was deleted meaning a new proposal can successfully |
| take place. Alternatively you could just start using a different |
| group id.</p> |
| </li> |
| <li><p>Always make sure that the node that has the Local Grouping Handler |
| is replicated. These means that on failover grouping will still |
| occur.</p> |
| </li> |
| <li><p>In case you are using group-timeouts, the remote node should have a |
| smaller group-timeout with at least half of the value on the main |
| coordinator. This is because this will determine how often the |
| last-time-use value should be updated with a round trip for a |
| request to the group between the nodes.</p> |
| </li> |
| </ol> |
| <h2 id="clustered-grouping-example">Clustered Grouping Example</h2> |
| <p>See the <a href="examples.html">examples</a> chapter for an example of how to configure message groups with a ActiveMQ Artemis Cluster.</p> |
| |
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