activemq-artemis/docs/user-manual/en/examples.xml

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<chapter id="examples">
<title>Examples</title>
<para>The HornetQ distribution comes with over 70 run out-of-the-box examples demonstrating many
of the features.</para>
<para>The examples are available in the distribution, in the <literal>examples</literal>
directory. Examples are split into JMS and core examples. JMS examples show how a particular
feature can be used by a normal JMS client. Core examples show how the equivalent feature
can be used by a core messaging client.</para>
<para>A set of Java EE examples are also provided which need WildFly
installed to be able to run.</para>
<section>
<title>JMS Examples</title>
<para>To run a JMS example, simply <literal>cd</literal> into the appropriate example
directory and type <literal>mvn verify</literal> (For details please read the readme.html
in each example directory).</para>
<para>Here's a listing of the examples with a brief description.</para>
<section id="examples.aerogear">
<title>JMS AeroGear</title>
<para>This example shows how you can send a message to a mobile device by leveraging
AeroGears push technology which provides support for different push notification technologies
like Google Cloud Messaging, Apple's APNs or Mozilla's SimplePush.</para>
</section>
<section id="examples.applet">
<title>Applet</title>
<para>This example shows you how to send and receive JMS messages from an Applet.</para>
</section>
<section id="application-level-failover">
<title>Application-Layer Failover</title>
<para>HornetQ also supports Application-Layer failover, useful in the case that
replication is not enabled on the server side.</para>
<para>With Application-Layer failover, it's up to the application to register a JMS
<literal>ExceptionListener</literal> with HornetQ which will be called by
HornetQ in the event that connection failure is detected.</para>
<para>The code in the <literal>ExceptionListener</literal> then recreates the JMS
connection, session, etc on another node and the application can continue.</para>
<para>Application-layer failover is an alternative approach to High Availability (HA).
Application-layer failover differs from automatic failover in that some client side
coding is required in order to implement this. Also, with Application-layer
failover, since the old session object dies and a new one is created, any
uncommitted work in the old session will be lost, and any unacknowledged messages
might be redelivered.</para>
</section>
<section id="examples.bridge">
<title>Core Bridge Example</title>
<para>The <literal>bridge</literal> example demonstrates a core bridge deployed on one
server, which consumes messages from a local queue and forwards them to an address
on a second server.</para>
<para>Core bridges are used to create message flows between any two HornetQ servers
which are remotely separated. Core bridges are resilient and will cope with
temporary connection failure allowing them to be an ideal choice for forwarding over
unreliable connections, e.g. a WAN.</para>
</section>
<section id="examples.browsers">
<title>Browser</title>
<para>The <literal>browser</literal> example shows you how to use a JMS <literal
>QueueBrowser</literal> with HornetQ.</para>
<para>Queues are a standard part of JMS, please consult the JMS 1.1 specification for
full details.</para>
<para> A <literal>QueueBrowser</literal> is used to look at messages on the queue
without removing them. It can scan the entire content of a queue or only messages
matching a message selector.</para>
</section>
<section>
<title>Client Kickoff</title>
<para>The <literal>client-kickoff</literal> example shows how to terminate client
connections given an IP address using the JMX management API.</para>
</section>
<section>
<title>Client side failover listener</title>
<para>The <literal>client-side-failoverlistener</literal> example shows how to register a listener to monitor
failover events</para>
</section>
<section>
<title>Client-Side Load-Balancing</title>
<para>The <literal>client-side-load-balancing</literal> example demonstrates how
sessions created from a single JMS <literal>Connection</literal> can
be created to different nodes of the cluster. In other words it demonstrates how
HornetQ does client-side load-balancing of sessions across the cluster.</para>
</section>
<section id="examples.clustered.durable">
<title>Clustered Durable Subscription</title>
<para>This example demonstrates a clustered JMS durable subscription</para>
</section>
<section id="examples.clustered.grouping">
<title>Clustered Grouping</title>
<para>This is similar to the message grouping example except that it demonstrates it
working over a cluster. Messages sent to different nodes with the same group id will
be sent to the same node and the same consumer.</para>
</section>
<section id="examples.clustered.queue">
<title>Clustered Queue</title>
<para>The <literal>clustered-queue</literal> example demonstrates a JMS queue deployed
on two different nodes. The two nodes are configured to form a cluster. We then
create a consumer for the queue on each node, and we create a producer on only one
of the nodes. We then send some messages via the producer, and we verify that both
consumers receive the sent messages in a round-robin fashion.</para>
</section>
<section id="examples.clustered.jgroups">
<title>Clustering with JGroups</title>
<para>The <literal>clustered-jgroups</literal> example demonstrates how to form a two
node cluster using JGroups as its underlying topology discovery technique, rather than
the default UDP broadcasting. We then create a consumer for the queue on each node,
and we create a producer on only one of the nodes. We then send some messages via the
producer, and we verify that both consumers receive the sent messages in a round-robin fashion.</para>
</section>
<section id="examples.clustered.standalone">
<title>Clustered Standalone</title>
<para>The <literal>clustered-standalone</literal> example demonstrates how to configure
and starts 3 cluster nodes on the same machine to form a cluster. A subscriber for a
JMS topic is created on each node, and we create a producer on only one of the
nodes. We then send some messages via the producer, and we verify that the 3
subscribers receive all the sent messages.</para>
</section>
<section id="examples.clustered.static.discovery">
<title>Clustered Static Discovery</title>
<para>This example demonstrates how to configure a cluster using a list of connectors rather
than UDP for discovery</para>
</section>
<section id="examples.clustered.static.oneway">
<title>Clustered Static Cluster One Way</title>
<para>This example demonstrates how to set up a cluster where cluster connections are one way,
i.e. server A -> Server B -> Server C</para>
</section>
<section>
<title>Clustered Topic</title>
<para>The <literal>clustered-topic</literal> example demonstrates a JMS topic deployed
on two different nodes. The two nodes are configured to form a cluster. We then
create a subscriber on the topic on each node, and we create a producer on only one
of the nodes. We then send some messages via the producer, and we verify that both
subscribers receive all the sent messages.</para>
</section>
<section id="examples.consumer-rate-limit">
<title>Message Consumer Rate Limiting</title>
<para>With HornetQ you can specify a maximum consume rate at which a JMS MessageConsumer
will consume messages. This can be specified when creating or deploying the
connection factory.</para>
<para>If this value is specified then HornetQ will ensure that messages are never
consumed at a rate higher than the specified rate. This is a form of consumer
throttling.</para>
</section>
<section id="examples.dead-letter">
<title>Dead Letter</title>
<para>The <literal>dead-letter</literal> example shows you how to define and deal with
dead letter messages. Messages can be delivered unsuccessfully (e.g. if the
transacted session used to consume them is rolled back). </para>
<para>Such a message goes back to the JMS destination ready to be redelivered. However,
this means it is possible for a message to be delivered again and again without any
success and remain in the destination, clogging the system.</para>
<para>To prevent this, messaging systems define dead letter messages: after a specified
unsuccessful delivery attempts, the message is removed from the destination and put
instead in a dead letter destination where they can be consumed for further
investigation.</para>
</section>
<section id="examples.delayed-redelivery">
<title>Delayed Redelivery</title>
<para>The <literal>delayed-redelivery</literal> example demonstrates how HornetQ can be
configured to provide a delayed redelivery in the case a message needs to be
redelivered.</para>
<para>Delaying redelivery can often be useful in the case that clients regularly fail or
roll-back. Without a delayed redelivery, the system can get into a "thrashing"
state, with delivery being attempted, the client rolling back, and delivery being
re-attempted in quick succession, using up valuable CPU and network
resources.</para>
</section>
<section id="divert-example">
<title>Divert</title>
<para>HornetQ diverts allow messages to be transparently "diverted" or copied from one
address to another with just some simple configuration defined on the server
side.</para>
</section>
<section>
<title>Durable Subscription</title>
<para>The <literal>durable-subscription</literal> example shows you how to use a durable
subscription with HornetQ. Durable subscriptions are a standard part of JMS, please
consult the JMS 1.1 specification for full details.</para>
<para>Unlike non-durable subscriptions, the key function of durable subscriptions is
that the messages contained in them persist longer than the lifetime of the
subscriber - i.e. they will accumulate messages sent to the topic even if there is
no active subscriber on them. They will also survive server restarts or crashes.
Note that for the messages to be persisted, the messages sent to them must be marked
as durable messages. </para>
</section>
<section id="examples.embedded.jms">
<title>Embedded</title>
<para>The <literal>embedded</literal> example shows how to embed JMS
within your own code using POJO instantiation and no config files.</para>
</section>
<section id="examples.embedded.jms.simple">
<title>Embedded Simple</title>
<para>The <literal>embedded</literal> example shows how to embed JMS within your own code using regular HornetQ XML files.</para>
</section>
<section id="examples.expiry">
<title>Message Expiration</title>
<para>The <literal>expiry</literal> example shows you how to define and deal with
message expiration. Messages can be retained in the messaging system for a limited
period of time before being removed. JMS specification states that clients should
not receive messages that have been expired (but it does not guarantee this will not
happen).</para>
<para>HornetQ can assign an expiry address to a given queue so that when messages
are expired, they are removed from the queue and sent to the expiry address.
These "expired" messages can later be consumed from the expiry address for
further inspection.</para>
</section>
<section id="examples.hornetq-ra-rar">
<title>HornetQ Resource Adapter example</title>
<para>This examples shows how to build the hornetq resource adapters a rar for deployment in other Application
Server's</para>
</section>
<section>
<title>HTTP Transport</title>
<para>The <literal>http-transport</literal> example shows you how to configure HornetQ
to use the HTTP protocol as its transport layer.</para>
</section>
<section>
<title>Instantiate JMS Objects Directly</title>
<para>Usually, JMS Objects such as <literal>ConnectionFactory</literal>, <literal
>Queue</literal> and <literal>Topic</literal> instances are looked up from JNDI
before being used by the client code. This objects are called "administered objects"
in JMS terminology.</para>
<para>However, in some cases a JNDI server may not be available or desired. To come to
the rescue HornetQ also supports the direct instantiation of these administered
objects on the client side so you don't have to use JNDI for JMS.</para>
</section>
<section id="examples.interceptor">
<title>Interceptor</title>
<para>HornetQ allows an application to use an interceptor to hook into the messaging
system. Interceptors allow you to handle various message events in HornetQ.</para>
</section>
<section id="examples.jaas">
<title>JAAS</title>
<para>The <literal>jaas</literal> example shows you how to configure HornetQ to use JAAS
for security. HornetQ can leverage JAAS to delegate user authentication and
authorization to existing security infrastructure.</para>
</section>
<section id="examples.jms.auto-closeable">
<title>JMS Auto Closable</title>
<para>The <literal>jms-auto-closeable</literal> example shows how JMS resources, such
as connections, sessions and consumers, in JMS 2 can be automatically closed on error.</para>
</section>
<section id="examples.jms.completion-listener">
<title>JMS Completion Listener</title>
<para>The <literal>jms-completion-listener</literal> example shows how to send a message
asynchronously to HornetQ and use a CompletionListener to be notified of the Broker
receiving it.</para>
</section>
<section id="examples.jms.jms-bridge">
<title>JMS Bridge</title>
<para>The <literal>jms-brige</literal> example shows how to setup a bridge
between two standalone HornetQ servers.</para>
</section>
<section id="examples.jms.jms-context">
<title>JMS Context</title>
<para>The <literal>jms-context</literal> example shows how to send and receive a message
to a JMS Queue using HornetQ by using a JMS Context.</para>
<para>A JMSContext is part of JMS 2.0 and combines the JMS Connection and Session Objects
into a simple Interface.</para>
</section>
<section id="examples.jms.jms-shared-consumer">
<title>JMS Shared Consumer</title>
<para>The <literal>jms-shared-consumer</literal> example shows you how can use shared
consumers to share a subscription on a topic. In JMS 1.1 this was not allowed and so caused
a scalability issue. In JMS 2 this restriction has been lifted so you can share the load
across different threads and connections.</para>
</section>
<section id="examples.jmx">
<title>JMX Management</title>
<para>The <literal>jmx</literal> example shows how to manage HornetQ using JMX.</para>
</section>
<section id="examples.large-message">
<title>Large Message</title>
<para>The <literal>large-message</literal> example shows you how to send and receive
very large messages with HornetQ. HornetQ supports the sending and receiving of huge
messages, much larger than can fit in available RAM on the client or server.
Effectively the only limit to message size is the amount of disk space you have on
the server.</para>
<para>Large messages are persisted on the server so they can survive a server restart.
In other words HornetQ doesn't just do a simple socket stream from the sender to the
consumer.</para>
</section>
<section id="examples.last-value-queue">
<title>Last-Value Queue</title>
<para>The <literal>last-value-queue</literal> example shows you how to define and deal
with last-value queues. Last-value queues are special queues which discard any
messages when a newer message with the same value for a well-defined last-value
property is put in the queue. In other words, a last-value queue only retains the
last value.</para>
<para>A typical example for last-value queue is for stock prices, where you are only
interested by the latest price for a particular stock.</para>
</section>
<section id="examples.management">
<title>Management</title>
<para>The <literal>management</literal> example shows how to manage HornetQ using JMS
Messages to invoke management operations on the server.</para>
</section>
<section id="examples.management-notifications">
<title>Management Notification</title>
<para>The <literal>management-notification</literal> example shows how to receive
management notifications from HornetQ using JMS messages. HornetQ servers emit
management notifications when events of interest occur (consumers are created or
closed, addresses are created or deleted, security authentication fails,
etc.).</para>
</section>
<section id="examples.message-counters">
<title>Message Counter</title>
<para>The <literal>message-counters</literal> example shows you how to use message
counters to obtain message information for a JMS queue.</para>
</section>
<section id="examples.message-group">
<title>Message Group</title>
<para>The <literal>message-group</literal> example shows you how to configure and use
message groups with HornetQ. Message groups allow you to pin messages so they are
only consumed by a single consumer. Message groups are sets of messages that has the
following characteristics:</para>
<para>
<itemizedlist>
<listitem>
<para>Messages in a message group share the same group id, i.e. they have
same JMSXGroupID string property values</para>
</listitem>
<listitem>
<para>The consumer that receives the first message of a group will receive
all the messages that belongs to the group</para>
</listitem>
</itemizedlist>
</para>
</section>
<section id="examples.message-group2">
<title>Message Group</title>
<para>The <literal>message-group2</literal> example shows you how to configure and use
message groups with HornetQ via a connection factory.</para>
</section>
<section id="examples.message-priority">
<title>Message Priority</title>
<para>Message Priority can be used to influence the delivery order for messages.</para>
<para>It can be retrieved by the message's standard header field 'JMSPriority' as
defined in JMS specification version 1.1. </para>
<para>The value is of type integer, ranging from 0 (the lowest) to 9 (the highest). When
messages are being delivered, their priorities will effect their order of delivery.
Messages of higher priorities will likely be delivered before those of lower
priorities. </para>
<para>Messages of equal priorities are delivered in the natural order of their arrival
at their destinations. Please consult the JMS 1.1 specification for full
details.</para>
</section>
<section id="examples.multiple.failover">
<title>Multiple Failover</title>
<para>This example demonstrates how to set up a live server with multiple backups</para>
</section>
<section id="examples.multiple.failover.failback">
<title>Multiple Failover Failback</title>
<para>This example demonstrates how to set up a live server with multiple backups but
forcing failover back to the original live server</para>
</section>
<section id="examples.no-consumer-buffering">
<title>No Consumer Buffering</title>
<para>By default, HornetQ consumers buffer messages from the server in a client side
buffer before you actually receive them on the client side. This improves
performance since otherwise every time you called receive() or had processed the
last message in a <literal>MessageListener onMessage()</literal> method, the HornetQ
client would have to go the server to request the next message, which would then get
sent to the client side, if one was available.</para>
<para>This would involve a network round trip for every message and reduce performance.
Therefore, by default, HornetQ pre-fetches messages into a buffer on each
consumer.</para>
<para>In some case buffering is not desirable, and HornetQ allows it to be switched off.
This example demonstrates that.</para>
</section>
<section id="examples.non-transaction-failover">
<title>Non-Transaction Failover With Server Data Replication</title>
<para>The <literal>non-transaction-failover</literal> example demonstrates two servers coupled
as a live-backup pair for high availability (HA), and a client using a <emphasis>non-transacted
</emphasis> JMS session failing over from live to backup when the live server is
crashed.</para>
<para>HornetQ implements failover of client connections between
live and backup servers. This is implemented by the replication of state between
live and backup nodes. When replication is configured and a live node crashes, the
client connections can carry and continue to send and consume messages. When non-transacted
sessions are used, once and only once message delivery is not guaranteed and it is possible
that some messages will be lost or delivered twice.</para>
</section>
<section id="examples.openwire">
<title>OpenWire</title>
<para>The <literal>Openwire</literal> example shows how to configure a HornetQ
server to communicate with an ActiveMQ JMS client that uses open-wire protocol.</para>
</section>
<section id="examples.paging">
<title>Paging</title>
<para>The <literal>paging</literal> example shows how HornetQ can support huge queues
even when the server is running in limited RAM. It does this by transparently
<emphasis>paging</emphasis> messages to disk, and <emphasis>depaging</emphasis>
them when they are required.</para>
</section>
<section id="examples.pre-acknowledge">
<title>Pre-Acknowledge</title>
<para>Standard JMS supports three acknowledgement modes:<literal>
AUTO_ACKNOWLEDGE</literal>, <literal>CLIENT_ACKNOWLEDGE</literal>, and <literal
>DUPS_OK_ACKNOWLEDGE</literal>. For a full description on these modes please
consult the JMS specification, or any JMS tutorial.</para>
<para>All of these standard modes involve sending acknowledgements from the client to
the server. However in some cases, you really don't mind losing messages in event of
failure, so it would make sense to acknowledge the message on the server before
delivering it to the client. This example demonstrates how HornetQ allows this with
an extra acknowledgement mode.</para>
</section>
<section id="producer-rate-limiting-example">
<title>Message Producer Rate Limiting</title>
<para>The <literal>producer-rte-limit</literal> example demonstrates how, with HornetQ,
you can specify a maximum send rate at which a JMS message producer will send
messages.</para>
</section>
<section id="examples.proton-qpid">
<title>Proton Qpid</title>
<para>HornetQ can be configured to accept requests from any AMQP client that supports the
1.0 version of the protocol. This <literal>proton-j</literal> example shows a simply
qpid java 1.0 client example.</para>
</section>
<section id="examples.proton-ruby">
<title>Proton Ruby</title>
<para>HornetQ can be configured to accept requests from any AMQP client that supports the
1.0 version of the protocol. This example shows a simply proton ruby client
that sends and receives messages</para>
</section>
<section id="examples.queue">
<title>Queue</title>
<para>A simple example demonstrating a JMS queue.</para>
</section>
<section id="examples.message-redistribution">
<title>Message Redistribution</title>
<para>The <literal>queue-message-redistribution</literal> example demonstrates message
redistribution between queues with the same name deployed in different nodes of a
cluster.</para>
</section>
<section id="examples.queue-requestor">
<title>Queue Requestor</title>
<para>A simple example demonstrating a JMS queue requestor.</para>
</section>
<section id="examples.queue-message-selector">
<title>Queue with Message Selector</title>
<para>The <literal>queue-selector</literal> example shows you how to selectively consume
messages using message selectors with queue consumers.</para>
</section>
<section id="examples.reattach-node">
<title>Reattach Node example</title>
<para>The <literal>Reattach Node</literal> example shows how a client can try to reconnect to
the same server instead of failing the connection immediately and
notifying any user ExceptionListener objects. HornetQ can be configured to automatically
retry the connection, and reattach to the server when it becomes available again across
the network.</para>
</section>
<section id="examples.replicated-failback">
<title>Replicated Failback example</title>
<para>An example showing how failback works when using replication, In this example a live server will replicate
all its Journal to a backup server as it updates it. When the live server crashes the backup takes over
from the live server and the client reconnects and carries on from where it left off.</para>
</section>
<section id="examples.replicated-failback-static">
<title>Replicated Failback static example</title>
<para>An example showing how failback works when using replication, but this time with static connectors</para>
</section>
<section id="examples.replicated-multiple-failover">
<title>Replicated multiple failover example</title>
<para>An example showing how to configure multiple backups when using replication</para>
</section>
<section id="examples.replicated-failover-transaction">
<title>Replicated Failover transaction example</title>
<para>An example showing how failover works with a transaction when using replication</para>
</section>
<section id="examples.request-reply">
<title>Request-Reply example</title>
<para>A simple example showing the JMS request-response pattern.</para>
</section>
<section id="examples.rest">
<title>Rest example</title>
<para>An example showing how to use the HornetQ Rest API</para>
</section>
<section id="examples.scheduled-message">
<title>Scheduled Message</title>
<para>The <literal>scheduled-message</literal> example shows you how to send a scheduled
message to a JMS Queue with HornetQ. Scheduled messages won't get delivered until a
specified time in the future.</para>
</section>
<section id="examples.security">
<title>Security</title>
<para>The <literal>security</literal> example shows you how configure and use role based
queue security with HornetQ.</para>
</section>
<section id="asynchronous-send-acknowledgements-example">
<title>Send Acknowledgements</title>
<para>The <literal>send-acknowledgements</literal> example shows you how to use
HornetQ's advanced <emphasis>asynchronous send acknowledgements</emphasis> feature
to obtain acknowledgement from the server that sends have been received and
processed in a separate stream to the sent messages. </para>
</section>
<section id="examples.jms.spring.integration">
<title>Spring Integration</title>
<para>This example shows how to use embedded JMS using HornetQ's Spring integration.</para>
</section>
<section id="examples.ssl-transport">
<title>SSL Transport</title>
<para>The <literal>ssl-enabled</literal> shows you how to configure SSL with HornetQ to
send and receive message.</para>
</section>
<section id="examples.static-message-selector">
<title>Static Message Selector</title>
<para>The <literal>static-selector</literal> example shows you how to configure a
HornetQ core queue with static message selectors (filters).</para>
</section>
<section id="examples.static-message-selector-jms">
<title>Static Message Selector Using JMS</title>
<para>The <literal>static-selector-jms</literal> example shows you how to configure a
HornetQ queue with static message selectors (filters) using JMS.</para>
</section>
<section id="examples.stomp">
<title>Stomp</title>
<para>The <literal>stomp</literal> example shows you how to configure a
HornetQ server to send and receive Stomp messages.</para>
</section>
<section id="examples.stomp1.1">
<title>Stomp1.1</title>
<para>The <literal>stomp</literal> example shows you how to configure a
HornetQ server to send and receive Stomp messages via a Stomp 1.1 connection.</para>
</section>
<section id="examples.stomp1.2">
<title>Stomp1.2</title>
<para>The <literal>stomp</literal> example shows you how to configure a
HornetQ server to send and receive Stomp messages via a Stomp 1.2 connection.</para>
</section>
<section id="examples.stomp-web-socket">
<title>Stomp Over Web Sockets</title>
<para>The <literal>stomp-websockets</literal> example shows you how to configure a
HornetQ server to send and receive Stomp messages directly from Web browsers (provided
they support Web Sockets).</para>
</section>
<section id="examples.symmetric-cluster">
<title>Symmetric Cluster</title>
<para>The <literal>symmetric-cluster</literal> example demonstrates a symmetric cluster
set-up with HornetQ.</para>
<para>HornetQ has extremely flexible clustering which allows you to set-up servers in
many different topologies. The most common topology that you'll perhaps be familiar
with if you are used to application server clustering is a symmetric cluster.</para>
<para>With a symmetric cluster, the cluster is homogeneous, i.e. each node is configured
the same as every other node, and every node is connected to every other node in the
cluster.</para>
</section>
<section id="examples.temporary-queue">
<title>Temporary Queue</title>
<para>A simple example demonstrating how to use a JMS temporary queue.</para>
</section>
<section id="examples.topic">
<title>Topic</title>
<para>A simple example demonstrating a JMS topic.</para>
</section>
<section id="topic-hierarchy-example">
<title>Topic Hierarchy</title>
<para>HornetQ supports topic hierarchies. With a topic hierarchy you can register a
subscriber with a wild-card and that subscriber will receive any messages sent to an
address that matches the wild card.</para>
</section>
<section id="examples.topic-selector-1">
<title>Topic Selector 1</title>
<para>The <literal>topic-selector-example1</literal> example shows you how to send
message to a JMS Topic, and subscribe them using selectors with HornetQ.</para>
</section>
<section id="examples.topic-selector-2">
<title>Topic Selector 2</title>
<para>The <literal>topic-selector-example2</literal> example shows you how to
selectively consume messages using message selectors with topic consumers.</para>
</section>
<section id="examples.transaction-failover">
<title>Transaction Failover</title>
<para>The <literal>transaction-failover</literal> example demonstrates two servers coupled
as a live-backup pair for high availability (HA), and a client using a transacted JMS
session failing over from live to backup when the live server is
crashed.</para>
<para>HornetQ implements failover of client connections between
live and backup servers. This is implemented by the sharing of a journal between the
servers. When a live node crashes, the
client connections can carry and continue to send and consume messages. When transacted
sessions are used, once and only once message delivery is guaranteed.</para>
</section>
<section id="examples.no-transaction-failover">
<title>Failover Without Transactions</title>
<para>The <literal>stop-server-failover</literal> example demonstrates failover of the
JMS connection from one node to another when the live server crashes using a JMS
non-transacted session.</para>
</section>
<section id="examples.transactional-session">
<title>Transactional Session</title>
<para>The <literal>transactional</literal> example shows you how to use a transactional
Session with HornetQ.</para>
</section>
<section>
<title>XA Heuristic</title>
<para>The <literal>xa-heuristic</literal> example shows you how to make an XA heuristic
decision through HornetQ Management Interface. A heuristic decision is a unilateral
decision to commit or rollback an XA transaction branch after it has been
prepared.</para>
</section>
<section>
<title>XA Receive</title>
<para>The <literal>xa-receive</literal> example shows you how message receiving behaves
in an XA transaction in HornetQ.</para>
</section>
<section>
<title>XA Send</title>
<para>The <literal>xa-send</literal> example shows you how message sending behaves in an
XA transaction in HornetQ.</para>
</section>
<section>
<title>XA with Transaction Manager</title>
<para>The <literal>xa-with-jta</literal> example shows you how to use JTA interfaces to
control transactions with HornetQ.</para>
</section>
</section>
<section>
<title>Core API Examples</title>
<para>To run a core example, simply <literal>cd</literal> into the appropriate example
directory and type <literal>ant</literal></para>
<section id="examples.embedded">
<title>Embedded</title>
<para>The <literal>embedded</literal> example shows how to embed the HornetQ server
within your own code.</para>
</section>
</section>
<section>
<title>Java EE Examples</title>
<para>Most of the Java EE examples can be run the following way. Simply navigate into the
appropriate example directory and type <literal>mvn verify</literal>. This will use Arquillian to run the Application
Server and deploy the application. Note that you must have WildFly installed and the JBOSS_HOME environment
variable set. Please refer to the examples documentation for further instructions.</para>
<note>
<para>When running the Java EE examples you may see warning messages in the WildFly log about incompatible client and
server versions. This is normal if a newer version of the HornetQ project is being used with a version of WildFly that
ships an older version of HornetQ. These examples should still complete without any functional errors.</para>
</note>
<section>
<title>EJB/JMS Transaction</title>
<para>An example that shows using an EJB and JMS together within a transaction.</para>
</section>
<section>
<title>Resource Adapter Configuration</title>
<para>This example demonstrates how to configure several properties on the HornetQ JCA
resource adaptor.</para>
</section>
<section>
<title>Resource Adapter Remote Server Configuration</title>
<para>This example demonstrates how to configure the HornetQ resource adapter to talk to a remote HornetQ server</para>
</section>
<section id="examples.javaee.jms-bridge">
<title>JMS Bridge</title>
<para>An example demonstrating the use of the HornetQ JMS bridge.</para>
</section>
<section>
<title>MDB (Message Driven Bean)</title>
<para>A simple set of examples of message driven beans, including failover examples.</para>
</section>
<section>
<title>Servlet Transport</title>
<para>An example of how to use the HornetQ servlet transport.</para>
</section>
<section>
<title>Servlet SSL Transport</title>
<para>An example of how to use the HornetQ servlet transport over SSL.</para>
</section>
<section id="xa-recovery-example">
<title>XA Recovery</title>
<para>An example of how XA recovery works within the JBoss Application server using
HornetQ.</para>
</section>
</section>
</chapter>