| 1 | <html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Architecture - Architecture Overview</title><meta value="Yoav Shapira" name="author"><meta value="yoavs@apache.org" name="email"></head><body vlink="#525D76" alink="#525D76" link="#525D76" text="#000000" bgcolor="#ffffff"><table cellspacing="0" width="100%" border="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img border="0" alt=" |
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| 2 | The Apache Tomcat Servlet/JSP Container |
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| 3 | " align="right" src="../images/tomcat.gif"></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 border="0" alt="Apache Logo" align="right" src="../images/asf-logo.gif"></a></td></tr></table><table cellspacing="4" width="100%" border="0"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr size="1" noshade></td></tr><tr><!--LEFT SIDE NAVIGATION--><td nowrap="true" valign="top" width="20%"><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 align="left" valign="top" width="80%"><table cellspacing="4" width="100%" border="0"><tr><td valign="top" align="left"><h1>Apache Tomcat Architecture</h1><h2>Architecture Overview</h2></td><td nowrap="true" valign="top" align="right"><small><a href="printer/overview.html"><img alt="Printer Friendly Version" border="0" src="../images/printer.gif"><br>print-friendly<br>version |
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| 4 | </a></small></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Overview"><strong>Overview</strong></a></font></td></tr><tr><td><blockquote> |
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| 5 | <p> |
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| 6 | This page provides an overview of the Tomcat server architecture. |
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| 7 | </p> |
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| 8 | </blockquote></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Terms"><strong>Terms</strong></a></font></td></tr><tr><td><blockquote> |
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| 9 | |
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| 10 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Server"><strong>Server</strong></a></font></td></tr><tr><td><blockquote> |
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| 11 | <p> |
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| 12 | In the Tomcat world, a |
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| 13 | <a href="../config/server.html">Server</a> represents the whole container. |
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| 14 | Tomcat provides a default implementation of the |
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| 15 | <a href="../catalina/docs/api/org/apache/catalina/Server.html">Server interface.</a>, |
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| 16 | and this is rarely customized by users. |
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| 17 | </p> |
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| 18 | </blockquote></td></tr></table> |
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| 19 | |
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| 20 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Service"><strong>Service</strong></a></font></td></tr><tr><td><blockquote> |
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| 21 | <p> |
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| 22 | A <a href="../config/service.html">Service</a> is an intermediate component |
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| 23 | which lives inside a Server and ties one or more Connectors to exactly one |
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| 24 | Engine. The Service element is rarely customized by users, as the default |
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| 25 | implementation is simple and sufficient: |
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| 26 | <a href="../catalina/docs/api/org/apache/catalina/Service.html">Service interface</a>. |
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| 27 | </p> |
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| 28 | </blockquote></td></tr></table> |
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| 29 | |
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| 30 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Engine"><strong>Engine</strong></a></font></td></tr><tr><td><blockquote> |
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| 31 | <p> |
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| 32 | An |
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| 33 | <a href="../config/engine.html">Engine</a> represents request processing |
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| 34 | pipeline for a specific Service. As a Service may have multiple Connectors, |
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| 35 | the Engine received and processes all requests from these connectors, handing |
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| 36 | the response back to the appropriate connector for transmission to the client. |
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| 37 | The <a href="../catalina/docs/api/org/apache/catalina/Engine.html">Engine interface</a> |
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| 38 | may be implemented to supply custom Engines, though this is uncommon. |
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| 39 | </p> |
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| 40 | <p> |
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| 41 | Note that the Engine may be used for Tomcat server clustering via the |
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| 42 | jvmRoute parameter. Read the Clustering documentation for more information. |
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| 43 | </p> |
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| 44 | </blockquote></td></tr></table> |
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| 45 | |
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| 46 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Host"><strong>Host</strong></a></font></td></tr><tr><td><blockquote> |
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| 47 | <p> |
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| 48 | A <a href="../config/host.html">Host</a> is an association of a network name, |
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| 49 | e.g. www.yourcompany.com, to the Tomcat server. An Engine may contain |
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| 50 | multiple hosts, and the Host element also supports network aliases such as |
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| 51 | yourcompany.com and abc.yourcompany.com. Users rarely create custom |
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| 52 | <a href="../catalina/docs/api/org/apache/catalina/Host.html">Hosts</a> |
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| 53 | because the |
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| 54 | <a href="../catalina/docs/api/org/apache/catalina/core/StandardHost.html">StandardHost |
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| 55 | implementation</a> provides significant additional functionality. |
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| 56 | </p> |
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| 57 | </blockquote></td></tr></table> |
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| 58 | |
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| 59 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Connector"><strong>Connector</strong></a></font></td></tr><tr><td><blockquote> |
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| 60 | <p> |
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| 61 | A Connector handles communications with the client. There are multiple |
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| 62 | connectors available with Tomcat, all of which implement the |
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| 63 | <a href="../catalina/docs/api/org/apache/catalina/Connector.html">Connector |
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| 64 | interface.</a> These include the |
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| 65 | <a href="../config/coyote.html">Coyote connector</a> which is used for |
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| 66 | most HTTP traffic, especially when running Tomcat as a standalone server, |
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| 67 | and the <a href="../config/jk2.html">JK2 connector</a> which implements |
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| 68 | the AJP procotol used when connecting Tomcat to an Apache HTTPD server. |
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| 69 | Creating a customized connector is a significant effort. |
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| 70 | </p> |
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| 71 | </blockquote></td></tr></table> |
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| 72 | |
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| 73 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Context"><strong>Context</strong></a></font></td></tr><tr><td><blockquote> |
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| 74 | <p> |
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| 75 | A |
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| 76 | <a href="../config/context.html">Context</a> |
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| 77 | represents a web application. A Host may contain multiple |
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| 78 | contexts, each with a unique path. The |
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| 79 | <a href="../catalina/docs/api/org/apache/catalina/Context.html">Context |
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| 80 | interface</a> may be implemented to create custom Contexts, but |
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| 81 | this is rarely the case because the |
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| 82 | <a href="../catalina/docs/api/org/apache/catalina/core/StandardContext.html"> |
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| 83 | StandardContext</a> provides significant additional functionality. |
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| 84 | </p> |
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| 85 | </blockquote></td></tr></table> |
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| 86 | </blockquote></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Comments"><strong>Comments</strong></a></font></td></tr><tr><td><blockquote> |
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| 87 | <p> |
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| 88 | Tomcat is designed to be a fast and efficient implementation of the |
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| 89 | Servlet Specification. Tomcat came about as the reference implementation |
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| 90 | of this specification, and has remained rigorous in adhering to the |
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| 91 | specification. At the same time, significant attention has been paid |
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| 92 | to Tomcat's performance and it is now on par with other servlet containers, |
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| 93 | including commercial ones. |
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| 94 | </p> |
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| 95 | <p> |
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| 96 | In recent releases of Tomcat, mostly starting with Tomcat 5, |
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| 97 | we have begun effots to make more aspects of Tomcat managable via |
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| 98 | JMX. In addition, the Manager and Admin webapps have been greatly |
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| 99 | enhanced and improved. Managability is a primary area of concern |
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| 100 | for us as the product matures and the specification becomes more |
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| 101 | stable. |
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| 102 | </p> |
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| 103 | </blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr size="1" noshade></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font size="-1" color="#525D76"><em> |
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| 104 | Copyright © 1999-2008, Apache Software Foundation |
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| 105 | </em></font></div></td></tr></table></body></html> |
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