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			105 lines
		
	
	
		
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			HTML
		
	
	
	
	
	
<html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Architecture - Architecture Overview</title><meta name="author" value="Yoav Shapira"><meta name="email" value="yoavs@apache.org"></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img src="../images/tomcat.gif" align="right" alt="
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      The Apache Tomcat Servlet/JSP Container
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    " border="0"></a></td><td><font face="arial,helvetica,sanserif"><h1>Apache Tomcat 6.0</h1></font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="../images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap="true"><p><strong>Links</strong></p><ul><li><a href="../index.html">Docs Home</a></li></ul><p><strong>Contents</strong></p><ul><li><a href="index.html">Contents</a></li><li><a href="overview.html">Overview</a></li><li><a href="startup.html">Server Startup</a></li><li><a href="requestProcess.html">Request Process</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left"><table border="0" width="100%" cellspacing="4"><tr><td align="left" valign="top"><h1>Apache Tomcat Architecture</h1><h2>Architecture Overview</h2></td><td align="right" valign="top" nowrap="true"><small><a href="printer/overview.html"><img src="../images/printer.gif" border="0" alt="Printer Friendly Version"><br>print-friendly<br>version
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                    </a></small></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Overview"><strong>Overview</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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This page provides an overview of the Tomcat server architecture.
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</p>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Terms"><strong>Terms</strong></a></font></td></tr><tr><td><blockquote>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Server"><strong>Server</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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In the Tomcat world, a
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<a href="../config/server.html">Server</a> represents the whole container.
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Tomcat provides a default implementation of the 
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<a href="../catalina/docs/api/org/apache/catalina/Server.html">Server interface.</a>,
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and this is rarely customized by users.
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</p>
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</blockquote></td></tr></table>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Service"><strong>Service</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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A <a href="../config/service.html">Service</a> is an intermediate component
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which lives inside a Server and ties one or more Connectors to exactly one
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Engine.  The Service element is rarely customized by users, as the default
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implementation is simple and sufficient:
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<a href="../catalina/docs/api/org/apache/catalina/Service.html">Service interface</a>.
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</p>
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</blockquote></td></tr></table>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Engine"><strong>Engine</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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An
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<a href="../config/engine.html">Engine</a> represents request processing
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pipeline for a specific Service.  As a Service may have multiple Connectors,
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the Engine received and processes all requests from these connectors, handing
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the response back to the appropriate connector for transmission to the client.
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The <a href="../catalina/docs/api/org/apache/catalina/Engine.html">Engine interface</a>
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may be implemented to supply custom Engines, though this is uncommon.
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</p>
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<p>
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Note that the Engine may be used for Tomcat server clustering via the
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jvmRoute parameter.  Read the Clustering documentation for more information.
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</p>
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</blockquote></td></tr></table>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Host"><strong>Host</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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A <a href="../config/host.html">Host</a> is an association of a network name,
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e.g. www.yourcompany.com, to the Tomcat server.  An Engine may contain
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multiple hosts, and the Host element also supports network aliases such as
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yourcompany.com and abc.yourcompany.com.  Users rarely create custom
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<a href="../catalina/docs/api/org/apache/catalina/Host.html">Hosts</a>
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because the 
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<a href="../catalina/docs/api/org/apache/catalina/core/StandardHost.html">StandardHost
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implementation</a> provides significant additional functionality.
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</p>
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</blockquote></td></tr></table>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Connector"><strong>Connector</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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A Connector handles communications with the client.  There are multiple
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connectors available with Tomcat, all of which implement the 
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<a href="../catalina/docs/api/org/apache/catalina/Connector.html">Connector
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interface.</a>  These include the
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<a href="../config/coyote.html">Coyote connector</a> which is used for
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most HTTP traffic, especially when running Tomcat as a standalone server, 
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and the <a href="../config/jk2.html">JK2 connector</a> which implements
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the AJP procotol used when connecting Tomcat to an Apache HTTPD server.
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Creating a customized connector is a significant effort.
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</p>
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</blockquote></td></tr></table>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Context"><strong>Context</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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A
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<a href="../config/context.html">Context</a>
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represents a web application.  A Host may contain multiple
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contexts, each with a unique path.  The
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<a href="../catalina/docs/api/org/apache/catalina/Context.html">Context
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interface</a> may be implemented to create custom Contexts, but
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this is rarely the case because the
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<a href="../catalina/docs/api/org/apache/catalina/core/StandardContext.html">
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StandardContext</a> provides significant additional functionality.
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</p>
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</blockquote></td></tr></table>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Comments"><strong>Comments</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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Tomcat is designed to be a fast and efficient implementation of the
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Servlet Specification.  Tomcat came about as the reference implementation
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of this specification, and has remained rigorous in adhering to the
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specification.  At the same time, significant attention has been paid
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to Tomcat's performance and it is now on par with other servlet containers,
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including commercial ones.
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</p>
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<p>
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In recent releases of Tomcat, mostly starting with Tomcat 5,
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we have begun effots to make more aspects of Tomcat managable via
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JMX.  In addition, the Manager and Admin webapps have been greatly
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enhanced and improved.  Managability is a primary area of concern
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for us as the product matures and the specification becomes more
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stable.
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</p>
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</blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font color="#525D76" size="-1"><em>
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        Copyright © 1999-2006, Apache Software Foundation
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