| <div class="docbook"><div class="navheader"><table summary="Navigation header" width="100%"><tr><th align="center" colspan="3">Chapter 4. Concepts</th></tr><tr><td align="left" width="20%"><a accesskey="p" href="Java-Broker-Getting-Started-CommandLine.html">Prev</a> </td><th align="center" width="60%"> </th><td align="right" width="20%"> <a accesskey="n" href="Java-Broker-Concepts-Broker.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a id="Java-Broker-Concepts"></a>Chapter 4. Concepts</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="Java-Broker-Concepts.html#Java-Broker-Concepts-Overview">4.1. Overview</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Broker.html">4.2. Broker</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Virtualhost-Nodes.html">4.3. Virtualhost Nodes</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-RemoteReplicationNodes.html">4.4. Remote Replication Nodes</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Virtualhosts.html">4.5. Virtualhosts</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Exchanges.html">4.6. Exchanges</a></span></dt><dd><dl><dt><span class="section"><a href="Java-Broker-Concepts-Exchanges.html#Java-Broker-Concepts-Exchanges-Predeclared">4.6.1. Predeclared Exchanges</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Exchanges.html#Java-Broker-Concepts-Exchanges-Types">4.6.2. Exchange Types</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Exchanges.html#Java-Broker-Concepts-Exchanges-BindingArguments">4.6.3. Binding Arguments</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Exchanges.html#Java-Broker-Concepts-Exchanges-UnroutableMessage">4.6.4. Unrouteable Messages</a></span></dt></dl></dd><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html">4.7. Queues</a></span></dt><dd><dl><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queues-Types">4.7.1. Types</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queues-Message-Grouping">4.7.2. Messaging Grouping</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queue-EnsureNonDestructiveConsumers">4.7.3. Forcing all consumers to be non-destructive</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queue-HoldingEntries">4.7.4. Holding messages on a Queue</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queue-OverflowPolicy">4.7.5. Controlling Queue Size</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Queues.html#Java-Broker-Concepts-Queues-SetLowPrefetch">4.7.6. Using low pre-fetch with special queue types</a></span></dt></dl></dd><dt><span class="section"><a href="Java-Broker-Concepts-Ports.html">4.8. Ports</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Authentication-Providers.html">4.9. Authentication Providers</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html">4.10. Other Services</a></span></dt><dd><dl><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html#Java-Broker-Concepts-Access-Control-Providers">4.10.1. Access Control Providers</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html#Java-Broker-Concepts-Group-Providers">4.10.2. Group Providers</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html#Java-Broker-Concepts-Keystores">4.10.3. Keystores</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html#Java-Broker-Concepts-Truststores">4.10.4. Truststores</a></span></dt><dt><span class="section"><a href="Java-Broker-Concepts-Other-Services.html#Java-Broker-Concepts-Loggers">4.10.5. Loggers</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Java-Broker-Concepts-Overview"></a>4.1. Overview</h2></div></div></div><p>The Broker comprises a number of entities. This section summaries the purpose of each of | |
| the entities and describes the relationships between them. These details are developed further | |
| in the sub-sections that follow.</p><p>The most important entity is the <span class="emphasis"><em>Virtualhost</em></span>. A virtualhost is an | |
| independent container in which messaging is performed. A <span class="emphasis"><em>virtualhost</em></span> exists | |
| in a container called a <span class="emphasis"><em>virtualhost node</em></span>. A virtualhost node has exactly | |
| one virtualhost.</p><p>An <span class="emphasis"><em>Exchange</em></span> accepts messages from a producer application and routes these | |
| to one or more <span class="emphasis"><em>Queues</em></span> according to pre-arranged criteria called | |
| <span class="emphasis"><em>bindings</em></span>. Exchange are an AMQP 0-8, 0-9, 0-9-1, 0-10 concept. They exist to | |
| produce useful messaging behaviours such as fanout. When using AMQP 0-8, 0-9, 0-9-1, or 0-10, the | |
| exchange is the only way ingressing a message into the virtualhost. When using AMQP | |
| 1.0, the application may route messages using an exchange (to take advantage of advanced behaviours) | |
| or it may publish messages direct to a queue. | |
| </p><p><span class="emphasis"><em>Queue</em></span>s are named entities that hold/buffer messages for later delivery to | |
| consumer applications. | |
| </p><p><span class="emphasis"><em>Ports</em></span> accept connections for messaging and management. The Broker | |
| supports any number of ports. When connecting for messaging, the user specifies a virtualhost | |
| name to indicate the virtualhost to which it is to be connected.</p><p><span class="emphasis"><em>Authentication Providers</em></span> assert the identity of the user as it connects | |
| for messaging or management. The Broker supports any number of authentication providers. Each | |
| port is associated with exactly one authentication provider. The port uses the authentication | |
| provider to assert the identity of the user as new connections are received.</p><p><span class="emphasis"><em>Group Providers</em></span> provide mechanisms that provide grouping of users. A | |
| Broker supports zero or more group providers.</p><p><span class="emphasis"><em>Access Control Provider</em></span> allows the abilities of users (or groups of | |
| users) to be restrained. A Broker can have zero or one access control providers.</p><p><span class="emphasis"><em>Keystores</em></span> provide a repositories of certificates and are used when the | |
| Broker accepts SSL connections. Any number of keystore providers can be defined. Keystores are | |
| be associated with Ports defined to accepts SSL.</p><p><span class="emphasis"><em>Truststores</em></span> provide a repositories of trust and are used to validate a | |
| peer. Any number of truststore provides can be defined. Truststores can be associated with Ports | |
| and other entities that form SSL connections.</p><p><span class="emphasis"><em>Remote Replication Nodes</em></span> are used when the high availability feature is | |
| in use. It is the remote representation of other virtualhost nodes that form part of the same | |
| group.</p><p><span class="emphasis"><em>Loggers</em></span>, at this point in the hierarchy, are responsible for the | |
| production of a log for the Broker.</p><p>These concepts will be developed over the forthcoming pages. The diagrams below also help | |
| put these entities in context of one and other.</p><p> | |
| </p><div class="figure"><a id="d0e399"></a><p class="title"><strong>Figure 4.1. Message Flow through Key Entities</strong></p><div class="figure-contents"><div class="mediaobject"><img alt="Message Flow through the Key Entities of the Broker" src="images/Broker-MessageFlow.png" /></div></div></div><p><br class="figure-break" /> | |
| </p><p> | |
| </p><div class="figure"><a id="d0e411"></a><p class="title"><strong>Figure 4.2. Broker Structure showing major entities</strong></p><div class="figure-contents"><div class="mediaobject"><img alt="Broker Structure" src="images/Broker-Model.png" /></div></div></div><p><br class="figure-break" /> | |
| </p></div></div><div class="navfooter"><hr /><table summary="Navigation footer" width="100%"><tr><td align="left" width="40%"><a accesskey="p" href="Java-Broker-Getting-Started-CommandLine.html">Prev</a> </td><td align="center" width="20%"> </td><td align="right" width="40%"> <a accesskey="n" href="Java-Broker-Concepts-Broker.html">Next</a></td></tr><tr><td align="left" valign="top" width="40%">3.5. Using the command line </td><td align="center" width="20%"><a accesskey="h" href="Apache-Qpid-Broker-J-Book.html">Home</a></td><td align="right" valign="top" width="40%"> 4.2. Broker</td></tr></table></div></div> |