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| <!DOCTYPE document [ |
| <!ENTITY project SYSTEM "project.xml"> |
| ]> |
| <document url="overview.html"> |
| |
| &project; |
| |
| <properties> |
| <author email="yoavs@apache.org">Yoav Shapira</author> |
| <title>Architecture Overview</title> |
| </properties> |
| |
| <body> |
| |
| |
| <section name="Overview"> |
| <p> |
| This page provides an overview of the Tomcat server architecture. |
| </p> |
| </section> |
| |
| <section name="Terms"> |
| |
| <subsection name="Server"> |
| <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> |
| </subsection> |
| |
| <subsection name="Service"> |
| <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> |
| </subsection> |
| |
| <subsection name="Engine"> |
| <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> |
| </subsection> |
| |
| <subsection name="Host"> |
| <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> |
| </subsection> |
| |
| <subsection name="Connector"> |
| <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 protocol used when connecting Tomcat to a web server such as |
| Apache HTTPD server. Creating a customized connector is a significant |
| effort. |
| </p> |
| </subsection> |
| |
| <subsection name="Context"> |
| <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> |
| </subsection> |
| </section> |
| |
| <section name="Comments"> |
| <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> |
| </section> |
| |
| </body> |
| </document> |