<div class="wiki-content maincontent"><h2 id="FAQ-FAQ">FAQ</h2>

<p>Here are a list of commonly asked questions and answers. If you have any questions which are not on this list, please talk to us on the <a shape="rect" href="discussion-forums.xml">forums</a>. </p>

<p>We <a shape="rect" href="contributing.xml">welcome contributions</a> and this entire website is a <a shape="rect" href="how-does-the-website-work.xml">wiki that you can edit</a> so please join in and help us make the documentation better!</p>

<h3 id="FAQ-General"><a shape="rect" href="general.xml">General</a></h3>


<p>General questions about ActiveMQ</p>

<ul class="childpages-macro"><li><a shape="rect" href="can-i-get-commercial-support.xml">Can I get commercial support</a></li><li><a shape="rect" href="how-can-i-get-help.xml">How can I get help</a></li><li><a shape="rect" href="how-can-i-get-the-source-code-from-subversion.xml">How can I get the source code from subversion</a></li><li><a shape="rect" href="how-does-activemq-compare-to-amqp.xml">How does ActiveMQ compare to AMQP</a></li><li><a shape="rect" href="how-does-activemq-compare-to-artemis.xml">How does ActiveMQ compare to Artemis</a></li><li><a shape="rect" href="how-does-activemq-compare-to-fuse-message-broker.xml">How does ActiveMQ compare to Fuse Message Broker</a></li><li><a shape="rect" href="how-does-activemq-compare-to-jbossmq.xml">How does ActiveMQ compare to JBossMQ</a></li><li><a shape="rect" href="how-does-activemq-compare-to-mantaray.xml">How does ActiveMQ compare to Mantaray</a></li><li><a shape="rect" href="how-does-activemq-compare-to-mule.xml">How does ActiveMQ compare to Mule</a></li><li><a shape="rect" href="how-does-activemq-compare-to-spread-toolkit.xml">How does ActiveMQ compare to Spread Toolkit</a></li><li><a shape="rect" href="how-does-openwire-compare-to-stomp.xml">How does OpenWire compare to Stomp</a></li><li><a shape="rect" href="how-does-the-website-work.xml">How does the website work</a></li><li><a shape="rect" href="how-do-i-avoid-maven-downloading-latest-jars.xml">How do I avoid Maven downloading latest jars</a></li><li><a shape="rect" href="how-do-i-build-but-disable-the-unit-tests.xml">How do I build but disable the unit tests</a></li><li><a shape="rect" href="how-do-i-compile-from-the-source.xml">How do I compile from the source</a></li><li><a shape="rect" href="how-do-i-edit-the-website.xml">How do I edit the website</a></li><li><a shape="rect" href="how-fast-is-activemq.xml">How fast is ActiveMQ</a></li><li><a shape="rect" href="should-i-run-activemq-on-windows-in-a-directory-with-spaces.xml">Should I run ActiveMQ on Windows in a directory with spaces</a></li><li><a shape="rect" href="what-is-activemq.xml">What is ActiveMQ</a></li><li><a shape="rect" href="what-is-the-license.xml">What is the license</a></li><li><a shape="rect" href="what-jars-do-i-need.xml">What jars do I need</a></li><li><a shape="rect" href="what-open-source-integration-solution-works-best-with-activemq.xml">What open source integration solution works best with ActiveMQ</a></li><li><a shape="rect" href="what-platforms-does-activemq-support.xml">What platforms does ActiveMQ support</a></li><li><a shape="rect" href="what-version-should-i-use.xml">What version should I use</a></li></ul>

<h3 id="FAQ-JMS"><a shape="rect" href="jms.xml">JMS</a></h3>


<p>Questions on using the JMS API and <a shape="rect" href="mom.xml">MOM</a> in general</p>

<ul class="childpages-macro"><li><a shape="rect" href="can-i-modify-messages-on-a-queue.xml">Can I modify messages on a queue</a></li><li><a shape="rect" href="can-i-send-and-receive-messages-concurrently-on-one-jms-connection.xml">Can I send and receive messages concurrently on one JMS Connection</a></li><li><a shape="rect" href="can-you-browse-a-topic.xml">Can you browse a topic</a></li><li><a shape="rect" href="how-do-durable-queues-and-topics-work.xml">How do durable queues and topics work</a></li><li><a shape="rect" href="how-does-a-queue-compare-to-a-topic.xml">How does a Queue compare to a Topic</a></li><li><a shape="rect" href="how-does-connectionfactory-relate-to-the-broker.xml">How does ConnectionFactory relate to the Broker</a></li><li><a shape="rect" href="how-does-jms-compare-with-email.xml">How does JMS compare with email</a></li><li><a shape="rect" href="how-do-i-consume-a-specific-message.xml">How do I consume a specific message</a></li><li><a shape="rect" href="how-do-i-get-started-with-jms.xml">How do I get started with JMS</a></li><li><a shape="rect" href="how-do-i-make-messages-durable.xml">How do I make messages durable</a></li><li><a shape="rect" href="how-do-i-send-messages-to-different-destinations-from-a-single-messageproducer.xml">How do I send messages to different Destinations from a single MessageProducer</a></li><li><a shape="rect" href="how-do-i-use-jms-efficiently.xml">How do I use JMS efficiently</a></li><li><a shape="rect" href="how-should-i-implement-request-response-with-jms.xml">How should I implement request response with JMS</a></li><li><a shape="rect" href="how-to-unit-test-jms-code.xml">How To Unit Test JMS Code</a></li><li><a shape="rect" href="multiple-consumers-on-a-queue.xml">Multiple consumers on a queue</a></li><li><a shape="rect" href="should-i-use-transactions.xml">Should I use transactions</a></li><li><a shape="rect" href="should-i-use-xa.xml">Should I use XA</a></li><li><a shape="rect" href="what-are-administered-objects.xml">What are administered objects</a></li></ul>

<h3 id="FAQ-UsingApacheActiveMQ"><a shape="rect" href="using-apache-activemq.xml">Using Apache ActiveMQ</a></h3>

Questions on using Apache ActiveMQ

<ul class="childpages-macro"><li><a shape="rect" href="activemq-command-line-tools-reference.xml">ActiveMQ Command Line Tools Reference</a></li><li><a shape="rect" href="are-destinations-case-sensitive.xml">Are destinations case sensitive</a></li><li><a shape="rect" href="can-i-send-really-large-files-over-activemq.xml">Can I send really large files over ActiveMQ</a></li><li><a shape="rect" href="can-i-use-activemq-5x-or-later-on-java-14.xml">Can I use ActiveMQ 5.x or later on Java 1.4</a></li><li><a shape="rect" href="can-two-brokers-share-the-same-database.xml">Can two brokers share the same database</a></li><li><a shape="rect" href="does-activemq-support-clustering.xml">Does ActiveMQ support clustering</a></li><li><a shape="rect" href="how-can-i-avoid-serialization-of-objects-in-objectmessage.xml">How can I avoid serialization of Objects in ObjectMessage</a></li><li><a shape="rect" href="how-can-i-get-a-list-of-the-topics-and-queues-in-a-broker.xml">How can I get a list of the topics and queues in a broker</a></li><li><a shape="rect" href="how-can-i-make-activemq-faster.xml">How can I make ActiveMQ faster</a></li><li><a shape="rect" href="how-can-i-monitor-activemq.xml">How can I monitor ActiveMQ</a></li><li><a shape="rect" href="how-can-i-monitor-the-connection-with-the-broker.xml">How can I monitor the connection with the broker</a></li><li><a shape="rect" href="how-can-i-see-what-destinations-are-used.xml">How can I see what destinations are used</a></li><li><a shape="rect" href="how-can-i-support-auto-reconnection.xml">How can I support auto reconnection</a></li><li><a shape="rect" href="how-can-i-support-priority-queues.xml">How can I support priority queues</a></li><li><a shape="rect" href="how-can-i-use-different-network-protocols.xml">How can I use different network protocols</a></li><li><a shape="rect" href="how-do-distributed-queues-work.xml">How do distributed queues work</a></li><li><a shape="rect" href="how-do-i-access-activemq-from-c.xml">How do I access ActiveMQ from C</a></li><li><a shape="rect" href="how-do-i-access-activemq-from-csharp-or-dotnet.xml">How do I access ActiveMQ from CSharp or dotNet</a></li><li><a shape="rect" href="how-do-i-access-activemq-from-ruby-perl-python-php.xml">How do I access ActiveMQ from Ruby, Perl, Python, PHP</a></li><li><a shape="rect" href="how-do-i-bridge-different-jms-providers.xml">How do I bridge different JMS providers</a></li><li><a shape="rect" href="how-do-i-change-dispatch-policy.xml">How do I change dispatch policy</a></li><li><a shape="rect" href="how-do-i-change-the-logging.xml">How do I change the logging</a></li><li><a shape="rect" href="how-do-i-connect-to-one-of-a-number-of-message-brokers.xml">How do I connect to one of a number of message brokers</a></li><li><a shape="rect" href="how-do-i-create-new-destinations.xml">How do I create new destinations</a></li><li><a shape="rect" href="how-do-i-delete-a-destination.xml">How do I delete a destination</a></li><li><a shape="rect" href="how-do-i-disable-logging.xml">How do I disable logging</a></li><li><a shape="rect" href="how-do-i-embed-a-broker-inside-a-connection.xml">How do I embed a Broker inside a Connection</a></li><li><a shape="rect" href="how-do-i-enable-asynchronous-sending.xml">How do I enable asynchronous sending</a></li><li><a shape="rect" href="how-do-i-enable-debug-logging.xml">How do I enable debug logging</a></li><li><a shape="rect" href="how-do-i-find-the-size-of-a-queue.xml">How do I find the Size of a Queue</a></li><li><a shape="rect" href="how-do-i-preserve-order-of-messages.xml">How do I preserve order of messages</a></li><li><a shape="rect" href="how-do-i-purge-a-queue.xml">How do I purge a queue</a></li><li><a shape="rect" href="how-do-i-restart-embedded-broker.xml">How do I restart embedded broker</a></li><li><a shape="rect" href="how-do-i-restrict-connections-from-creating-new-queues-or-topics.xml">How do I restrict connections from creating new queues or topics</a></li><li><a shape="rect" href="how-do-i-run-a-broker.xml">How do I run a broker</a></li><li><a shape="rect" href="how-do-i-set-the-message-expiration.xml">How do I set the message expiration</a></li><li><a shape="rect" href="how-do-i-turn-off-creating-an-embedded-activemq-broker-when-using-the-vm-transport.xml">How do I turn off creating an embedded ActiveMQ broker when using the VM transport</a></li><li><a shape="rect" href="how-do-i-unack-the-message-with-stomp.xml">How do I unack the message with Stomp</a></li><li><a shape="rect" href="how-do-i-use-activemq-using-in-jvm-messaging.xml">How do I use ActiveMQ using in JVM messaging</a></li><li><a shape="rect" href="how-do-i-use-durable-subscribers-in-a-network-of-brokers.xml">How do I use durable subscribers in a network of brokers</a></li><li><a shape="rect" href="how-do-i-use-ivy-with-activemq.xml">How do I use Ivy with ActiveMQ</a></li><li><a shape="rect" href="how-do-i-use-log4j-jms-appender-with-activemq.xml">How do I use log4j JMS appender with ActiveMQ</a></li><li><a shape="rect" href="how-do-i-use-ssl.xml">How do I use SSL</a></li><li><a shape="rect" href="how-do-message-groups-compare-to-selectors.xml">How do Message Groups compare to Selectors</a></li><li><a shape="rect" href="how-do-multiple-transports-work.xml">How do multiple transports work</a></li><li><a shape="rect" href="how-do-transactions-work.xml">How Do Transactions Work</a></li><li><a shape="rect" href="how-lightweight-is-sending-a-message.xml">How lightweight is sending a message</a></li><li><a shape="rect" href="how-should-i-package-applications-using-camel-and-activemq.xml">How should I package applications using Camel and ActiveMQ</a></li><li><a shape="rect" href="how-should-i-use-the-vm-transport.xml">How should I use the VM transport</a></li><li><a shape="rect" href="how-to-deal-with-large-number-of-threads-in-clients.xml">How to deal with large number of threads in clients</a></li><li><a shape="rect" href="how-to-disable-auto-destination-creation.xml">How to disable auto destination creation</a></li><li><a shape="rect" href="i-see-nc-client-ids-what-does-that-mean.xml">I see NC_ client-ids, what does that mean</a></li><li><a shape="rect" href="should-i-deploy-enterprise-integration-patterns-in-the-broker-or-another-application.xml">Should I deploy Enterprise Integration Patterns in the broker or another application</a></li><li><a shape="rect" href="should-i-deploy-the-broker-inside-my-jvm-or-appserver.xml">Should I deploy the broker inside my JVM or AppServer</a></li><li><a shape="rect" href="what-are-those-topics-activemqadvisory.xml">What are those topics ActiveMQ.Advisory</a></li><li><a shape="rect" href="what-happens-with-a-fast-producer-and-slow-consumer.xml">What happens with a fast producer and slow consumer</a></li><li><a shape="rect" href="what-is-the-difference-between-a-virtual-topic-and-a-composite-destination.xml">What is the difference between a Virtual Topic and a Composite Destination</a></li><li><a shape="rect" href="what-is-the-difference-between-discovery-multicast-and-zeroconf.xml">What is the difference between discovery, multicast and zeroconf</a></li><li><a shape="rect" href="what-is-the-prefetch-limit-for.xml">What is the Prefetch Limit For?</a></li><li><a shape="rect" href="while-posting-large-binary-file-to-activemq-is-there-a-way-to-measure-its-progress.xml">While posting large binary file to activeMQ, is there a way to measure its progress</a></li></ul>

<h3 id="FAQ-Configuration"><a shape="rect" href="configuration.xml">Configuration</a></h3>


<p>Questions on configuring ActiveMQ's JMS client or the Message Broker</p>

<ul class="childpages-macro"><li><a shape="rect" href="how-can-i-enable-detailed-logging.xml">How can I enable detailed logging</a></li><li><a shape="rect" href="how-does-xbean-compare-to-spring-2.xml">How does XBean compare to Spring 2</a></li><li><a shape="rect" href="how-do-i-configure-10s-of-1000s-of-queues-in-a-single-broker.xml">How do I configure 10s of 1000s of Queues in a single broker</a></li><li><a shape="rect" href="how-do-i-configure-activemq-to-hold-100s-of-millions-of-queue-messages.xml">How do I configure ActiveMQ to hold 100s of millions of Queue Messages</a></li><li><a shape="rect" href="how-do-i-configure-activemq-to-use-aio-server-transport.xml">How do I configure ActiveMQ to use AIO server transport</a></li><li><a shape="rect" href="how-do-i-configure-automatic-reconnection.xml">How do I configure automatic reconnection</a></li><li><a shape="rect" href="how-do-i-configure-distributed-queues-or-topics.xml">How do I configure distributed queues or topics</a></li><li><a shape="rect" href="how-do-i-configure-the-queues-i-want.xml">How do I configure the queues I want</a></li><li><a shape="rect" href="how-do-i-define-a-local-address-and-local-port-for-tcp-or-ssl.xml">How do I define a local address and local port for TCP or SSL</a></li><li><a shape="rect" href="how-do-i-disable-persistence.xml">How do I disable persistence</a></li><li><a shape="rect" href="how-do-i-run-activemq-under-the-kaffe-jvm.xml">How do I run ActiveMQ under the Kaffe JVM</a></li><li><a shape="rect" href="how-to-configure-a-new-database.xml">How to configure a new database</a></li><li><a shape="rect" href="how-to-deploy-activemq-ra-versionrar-to-weblogic.xml">How to deploy activemq-ra-version.rar to weblogic</a></li><li><a shape="rect" href="how-to-disable-multicast-discovery.xml">How to disable multicast discovery</a></li></ul>

<h3 id="FAQ-PersistenceQuestions"><a shape="rect" href="persistence-questions.xml">Persistence Questions</a></h3>

Questions relating to long term persistence of messages.

<ul class="childpages-macro"><li><a shape="rect" href="are-messages-read-directly-from-the-journal.xml">Are messages read directly from the journal</a></li><li><a shape="rect" href="does-activemq-support-my-sql-database.xml">Does ActiveMQ support my SQL database</a></li><li><a shape="rect" href="how-does-journaling-work-with-multiple-brokers.xml">How does journaling work with multiple brokers</a></li><li><a shape="rect" href="how-does-the-journal-work.xml">How does the journal work</a></li><li><a shape="rect" href="how-do-i-back-up-kahadb.xml">How do I back-up KahaDB</a></li><li><a shape="rect" href="how-do-i-change-the-message-store-directory-for-an-embedded-broker.xml">How do I change the message store directory for an embedded broker</a></li><li><a shape="rect" href="is-there-a-specified-size-of-the-journal.xml">Is there a specified size of the journal</a></li><li><a shape="rect" href="what-happens-when-the-journal-size-is-exceeded.xml">What happens when the journal size is exceeded</a></li><li><a shape="rect" href="what-is-the-difference-between-persistent-and-non-persistent-delivery.xml">What is the difference between persistent and non-persistent delivery</a></li></ul>

<h3 id="FAQ-Errors"><a shape="rect" href="errors.xml">Errors</a></h3>


<p>Questions on specific kinds of errors. If you have seen a specific exception then check the <a shape="rect" href="exceptions.xml">Exceptions</a></p>

<ul class="childpages-macro"><li><a shape="rect" href="could-not-find-packetreader-for-packet-type-unknown-packet-type.xml">Could not find PacketReader for packet type - UNKNOWN PACKET TYPE</a></li><li><a shape="rect" href="exceptions.xml">Exceptions</a><ul class="childpages-macro"><li><a shape="rect" href="certificateunknown.xml">certificate_unknown</a></li><li><a shape="rect" href="ioexception-could-not-find-class-for-resource.xml">IOException - could not find class for resource</a></li><li><a shape="rect" href="javaiointerruptedioexception.xml">java.io.InterruptedIOException</a></li><li><a shape="rect" href="javaioioexception-failed-to-create-database-derbydb-see-the-next-exception-for-details.xml">java.io.IOException Failed to create database 'derbydb', see the next exception for details</a></li><li><a shape="rect" href="javalangnosuchmethoderror.xml">java.lang.NoSuchMethodError</a></li><li><a shape="rect" href="javalangnosuchmethodexception-orgactivemqraactivemqresourceadaptersetuseembeddedbroker.xml">java.lang.NoSuchMethodException org.activemq.ra.ActiveMQResourceAdapter.setUseEmbeddedBroker</a></li><li><a shape="rect" href="javalangoutofmemory.xml">java.lang.OutOfMemory</a></li><li><a shape="rect" href="javaxjmsjmsexception-wire-format-negociation-timeout-peer-did-not-send-his-wire-format.xml">javax.jms.JMSException - Wire format negociation timeout - peer did not send his wire format.</a></li><li><a shape="rect" href="jaxb-20-api-is-being-loaded-from-the-bootstrap-classloader-but-this-ri-needs-21-api.xml">JAXB 2.0 API is being loaded from the bootstrap classloader, but this RI () needs 2.1 API.</a></li><li><a shape="rect" href="jaxb-20-api-is-being-loaded-from-the-bootstrap-classloader-but-this-ri-xxx-needs-21-api.xml">JAXB 2.0 API is being loaded from the bootstrap classloader, but this RI (xxx) needs 2.1 API</a></li><li><a shape="rect" href="journal-is-already-opened-by-this-application.xml">Journal is already opened by this application</a></li><li><a shape="rect" href="noclassdeffounderror-orgspringframeworkcoreioresource.xml">NoClassDefFoundError - org.springframework.core.io.Resource</a></li><li><a shape="rect" href="no-suitable-driver.xml">No suitable driver</a></li></ul></li><li><a shape="rect" href="i-am-having-problems-with-the-spring-jmstemplate.xml">I am having problems with the Spring JmsTemplate</a></li><li><a shape="rect" href="i-am-not-receiving-any-messages-what-is-wrong.xml">I am not receiving any messages, what is wrong</a></li><li><a shape="rect" href="i-cannot-connect-to-activemq-from-jconsole.xml">I cannot connect to ActiveMQ from JConsole</a></li><li><a shape="rect" href="i-do-not-receive-messages-in-my-second-consumer.xml">I do not receive messages in my second consumer</a></li><li><a shape="rect" href="i-get-errors-building-the-code-whats-wrong.xml">I get errors building the code whats wrong</a></li><li><a shape="rect" href="log4j-warn-no-appenders-could-be-found-for-logger.xml">log4j-WARN No appenders could be found for logger</a></li><li><a shape="rect" href="multicast-watch-out-for-ipv6-vs-ipv4-support-on-your-operating-system-or-distribution-or-network.xml">Multicast - Watch out for IPV6 vs IPV4 support on your operating system or distribution or network</a></li><li><a shape="rect" href="my-producer-blocks.xml">My producer blocks</a></li><li><a shape="rect" href="onmessage-method-of-messagelistener-is-never-called.xml">onMessage method of MessageListener is never called</a></li><li><a shape="rect" href="resource-adapter-does-not-seem-to-pool-connections.xml">Resource Adapter does not seem to pool connections</a></li><li><a shape="rect" href="slow-networks-drop-large-messages.xml">Slow networks drop large messages</a></li><li><a shape="rect" href="the-broker-will-not-start.xml">The Broker will not start</a></li><li><a shape="rect" href="the-vm-transport-starts-a-broker-before-my-configured-broker-starts.xml">The vm transport starts a broker before my configured broker starts</a></li><li><a shape="rect" href="why-do-i-not-get-all-of-the-messages-i-sent.xml">Why do I not get all of the messages I sent</a></li><li><a shape="rect" href="why-do-i-not-receive-messages-on-my-durable-topic-subscription.xml">Why do I not receive messages on my durable topic subscription</a></li><li><a shape="rect" href="why-do-kahadb-log-files-remain-after-cleanup.xml">Why do KahaDB log files remain after cleanup</a></li></ul>

<h3 id="FAQ-DevelopingActiveMQ"><a shape="rect" href="developing-activemq.xml">Developing ActiveMQ</a></h3>

Questions for developers wishing to extend or enhance Apache ActiveMQ

<ul class="childpages-macro"><li><a shape="rect" href="how-can-i-add-a-new-type-of-transport.xml">How can I add a new type of transport</a></li><li><a shape="rect" href="how-can-i-contribute.xml">How can I contribute</a></li><li><a shape="rect" href="how-do-i-add-my-own-plugins.xml">How do I add my own plugins</a></li><li><a shape="rect" href="how-do-i-debug-activemq-from-my-ide.xml">How do I debug ActiveMQ from my IDE</a></li></ul>

<h3 id="FAQ-Terminology"><a shape="rect" href="terminology.xml">Terminology</a></h3>

<p>A list of the various messaging related terms and acronyms.</p>

<ul class="childpages-macro"><li><a shape="rect" href="dr.xml">DR</a></li><li><a shape="rect" href="ha.xml">HA</a></li><li><a shape="rect" href="latency.xml">Latency</a></li><li><a shape="rect" href="mom.xml">MOM</a></li><li><a shape="rect" href="qos.xml">QoS</a></li><li><a shape="rect" href="seda.xml">SEDA</a></li><li><a shape="rect" href="throughput.xml">Throughput</a></li></ul>

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