| <html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Architecture (6.0.39) - Architecture Overview</title><meta name="author" content="Yoav Shapira"><style type="text/css" media="print"> | |
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| </style></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=" | |
| The Apache Tomcat Servlet/JSP Container | |
| " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 6.0</font></h1><font face="arial,helvetica,sanserif">Version 6.0.39, Jan 27 2014</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="nowrap" class="noPrint"><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" id="mainBody"><h1>Apache Tomcat Architecture</h1><h2>Architecture Overview</h2><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> | |
| <p> | |
| This page provides an overview of the Tomcat server architecture. | |
| </p> | |
| </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> | |
| <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> | |
| <p> | |
| In the Tomcat world, a | |
| <a href="../config/server.html">Server</a> represents the whole container. | |
| Tomcat provides a default implementation of the | |
| <a href="../api/org/apache/catalina/Server.html">Server interface</a> | |
| which is rarely customized by users. | |
| </p> | |
| </blockquote></td></tr></table> | |
| <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> | |
| <p> | |
| A <a href="../config/service.html">Service</a> is an intermediate component | |
| which lives inside a Server and ties one or more Connectors to exactly one | |
| Engine. The Service element is rarely customized by users, as the default | |
| implementation is simple and sufficient: | |
| <a href="../api/org/apache/catalina/Service.html">Service interface</a>. | |
| </p> | |
| </blockquote></td></tr></table> | |
| <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> | |
| <p> | |
| An | |
| <a href="../config/engine.html">Engine</a> represents request processing | |
| pipeline for a specific Service. As a Service may have multiple Connectors, | |
| the Engine receives and processes all requests from these connectors, handing | |
| the response back to the appropriate connector for transmission to the client. | |
| The <a href="../api/org/apache/catalina/Engine.html">Engine interface</a> | |
| may be implemented to supply custom Engines, though this is uncommon. | |
| </p> | |
| <p> | |
| Note that the Engine may be used for Tomcat server clustering via the | |
| jvmRoute parameter. Read the Clustering documentation for more information. | |
| </p> | |
| </blockquote></td></tr></table> | |
| <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> | |
| <p> | |
| A <a href="../config/host.html">Host</a> is an association of a network name, | |
| e.g. www.yourcompany.com, to the Tomcat server. An Engine may contain | |
| multiple hosts, and the Host element also supports network aliases such as | |
| yourcompany.com and abc.yourcompany.com. Users rarely create custom | |
| <a href="../api/org/apache/catalina/Host.html">Hosts</a> | |
| because the | |
| <a href="../api/org/apache/catalina/core/StandardHost.html">StandardHost | |
| implementation</a> provides significant additional functionality. | |
| </p> | |
| </blockquote></td></tr></table> | |
| <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> | |
| <p> | |
| A Connector handles communications with the client. There are multiple | |
| connectors available with Tomcat. These include the | |
| <a href="../config/http.html">HTTP connector</a> which is used for | |
| most HTTP traffic, especially when running Tomcat as a standalone server, | |
| and the <a href="../config/ajp.html">AJP connector</a> which implements | |
| the AJP procotol used when connecting Tomcat to a web server such as | |
| Apache HTTPD server. Creating a customized connector is a significant | |
| effort. | |
| </p> | |
| </blockquote></td></tr></table> | |
| <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> | |
| <p> | |
| A | |
| <a href="../config/context.html">Context</a> | |
| represents a web application. A Host may contain multiple | |
| contexts, each with a unique path. The | |
| <a href="../api/org/apache/catalina/Context.html">Context | |
| interface</a> may be implemented to create custom Contexts, but | |
| this is rarely the case because the | |
| <a href="../api/org/apache/catalina/core/StandardContext.html"> | |
| StandardContext</a> provides significant additional functionality. | |
| </p> | |
| </blockquote></td></tr></table> | |
| </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> | |
| <p> | |
| Tomcat is designed to be a fast and efficient implementation of the | |
| Servlet Specification. Tomcat came about as the reference implementation | |
| of this specification, and has remained rigorous in adhering to the | |
| specification. At the same time, significant attention has been paid | |
| to Tomcat's performance and it is now on par with other servlet containers, | |
| including commercial ones. | |
| </p> | |
| <p> | |
| In recent releases of Tomcat, mostly starting with Tomcat 5, | |
| we have begun efforts to make more aspects of Tomcat manageable via | |
| JMX. In addition, the Manager and Admin webapps have been greatly | |
| enhanced and improved. Manageability is a primary area of concern | |
| for us as the product matures and the specification becomes more | |
| stable. | |
| </p> | |
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