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    <title>2.2&nbsp;What is the Virgo Tomcat Server?</title><link rel="stylesheet" href="css/stylesheet.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="Virgo Programmer Guide"><link rel="up" href="ch02.html" title="2.&nbsp;Introduction to the Virgo Tomcat Server"><link rel="prev" href="ch02.html" title="2.&nbsp;Introduction to the Virgo Tomcat Server"><link rel="next" href="ch02s03.html" title="2.3&nbsp;Why the Virgo Tomcat Server?"><!--Begin Google Analytics code--><script type="text/javascript">
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 	  	    The Virgo Tomcat Server, or VTS for short, is the runtime portion of the Virgo Server.
 	        It is a lightweight, modular, OSGi-based runtime that provides a complete packaged solution for developing,
 	        deploying, and managing enterprise applications.
 			By leveraging several best-of-breed technologies and improving upon
 			them, the VTS offers a compelling solution to develop and deploy
 			enterprise applications.
 		</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="introduction-constituents"></a>What Makes up the Virgo Tomcat Server?</h3></div></div></div><p>
 				The Virgo Tomcat Server is built on top of the following core technologies:
 			</p><div class="itemizedlist"><ul type="disc"><li><a class="ulink" href="http://www.springframework.org/" target="_top">Spring Framework</a>, obviously!</li><li><a class="ulink" href="http://tomcat.apache.org/" target="_top">Tomcat</a> as the web container.</li><li><a class="ulink" href="http://www.osgi.org/Specifications/HomePage" target="_top">OSGi R4.3</a>.</li><li><a class="ulink" href="http://www.eclipse.org/equinox/" target="_top">Equinox</a> as the OSGi implementation.</li><li><a class="ulink" href="http://www.springframework.org/osgi/" target="_top">Spring Dynamic Modules for OSGi</a> for working with OSGi in a Spring application.</li><li><a class="ulink" href="http://www.springsource.com/products/sts" target="_top">SpringSource Tool Suite</a> for developing applications.</li></ul></div><p>
 				Note, however, that the Virgo Tomcat Server isn&#8217;t just a combination
 				of these technologies. Rather, it integrates and extends these
 				technologies to provide many features essential for developing,
 				deploying, and managing today&#8217;s enterprise Java applications.
 			</p></div><p>
 			The following diagram presents a high-level overview of the VTS&#8217;s architecture.
 		</p><p>
 			<img src="images/introduction-architecture.png">
 		</p><p>
 			At the heart of the Virgo Tomcat Server is the Virgo Kernel or VK.
 			The VK is an OSGi-based kernel that takes full advantage of the modularity
 			and versioning of the OSGi platform. The VK builds on Equinox and extends its capabilities for
 			provisioning and library management, as well as providing core functionality for the VTS.
 		</p><p>
 			To maintain a minimal runtime footprint, OSGi bundles are installed on demand by the
 			VK. This allows for an application to be installed into a running
 			VTS and for its dependencies to be satisfied from an external repository. Not only
 			does this remove the need to manually install all your application dependencies, which
 			would be tedious, but it also keeps memory usage to a minimum.
 		</p><p>
 			As shown in the figure, VK runs on top of Equinox within a standard Java
 			Virtual Machine. Above the VK further layers contribute functionality
 			to the VTS. Such as management, serviceability and web application support.
 		</p><p>
 			Version 3.0.3.RELEASE of the Virgo Tomcat Server supports <span class="emphasis"><em>bundle</em></span>,
 			<span class="emphasis"><em>plan</em></span>, <span class="emphasis"><em>PAR</em></span>, <span class="emphasis"><em>configuration</em></span>,
 			<span class="emphasis"><em>Web Application Bundle (WAB)</em></span>, and <span class="emphasis"><em>WAR</em></span> artifacts, which enable
 			you to build sophisticated web applications. This includes support for
 			standard Java EE WARs, "shared library" WARs, and "shared services" WARs, each of
 			which will be covered in greater detail in <a class="xref" href="ch03.html" title="3.&nbsp;Deployment Architecture">Chapter&nbsp;3, <i>Deployment Architecture</i></a>.
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	</script><!--End Google Analytics code--></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.2 What is the Virgo Tomcat Server?</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch02.html">Prev</a> </td><th width="60%" align="center">2. Introduction to the Virgo Tomcat Server</th><td width="20%" align="right"> <a accesskey="n" href="ch02s03.html">Next</a></td></tr></table><hr></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="introduction-what"></a>2.2 What is the Virgo Tomcat Server?</h2></div></div></div><p>
	The Virgo Tomcat Server, or VTS for short, is the runtime portion of the Virgo Server.
	It is a lightweight, modular, OSGi-based runtime that provides a complete packaged solution for developing,
	deploying, and managing enterprise applications.
	By leveraging several best-of-breed technologies and improving upon
	them, the VTS offers a compelling solution to develop and deploy
	enterprise applications.
	</p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="introduction-constituents"></a>What Makes up the Virgo Tomcat Server?</h3></div></div></div><p>
	The Virgo Tomcat Server is built on top of the following core technologies:
	</p><div class="itemizedlist"><ul type="disc"><li><a class="ulink" href="http://www.springframework.org/" target="_top">Spring Framework</a>, obviously!</li><li><a class="ulink" href="http://tomcat.apache.org/" target="_top">Tomcat</a> as the web container.</li><li><a class="ulink" href="http://www.osgi.org/Specifications/HomePage" target="_top">OSGi R4.3</a>.</li><li><a class="ulink" href="http://www.eclipse.org/equinox/" target="_top">Equinox</a> as the OSGi implementation.</li><li><a class="ulink" href="http://www.springframework.org/osgi/" target="_top">Spring Dynamic Modules for OSGi</a> for working with OSGi in a Spring application.</li><li><a class="ulink" href="http://www.springsource.com/products/sts" target="_top">SpringSource Tool Suite</a> for developing applications.</li></ul></div><p>
	Note, however, that the Virgo Tomcat Server isn’t just a combination
	of these technologies. Rather, it integrates and extends these
	technologies to provide many features essential for developing,
	deploying, and managing today’s enterprise Java applications.
	</p></div><p>
	The following diagram presents a high-level overview of the VTS’s architecture.
	</p><p>
	<img src="images/introduction-architecture.png">
	</p><p>
	At the heart of the Virgo Tomcat Server is the Virgo Kernel or VK.
	The VK is an OSGi-based kernel that takes full advantage of the modularity
	and versioning of the OSGi platform. The VK builds on Equinox and extends its capabilities for
	provisioning and library management, as well as providing core functionality for the VTS.
	</p><p>
	To maintain a minimal runtime footprint, OSGi bundles are installed on demand by the
	VK. This allows for an application to be installed into a running
	VTS and for its dependencies to be satisfied from an external repository. Not only
	does this remove the need to manually install all your application dependencies, which
	would be tedious, but it also keeps memory usage to a minimum.
	</p><p>
	As shown in the figure, VK runs on top of Equinox within a standard Java
	Virtual Machine. Above the VK further layers contribute functionality
	to the VTS. Such as management, serviceability and web application support.
	</p><p>
	Version 3.0.3.RELEASE of the Virgo Tomcat Server supports <span class="emphasis"><em>bundle</em></span>,
	<span class="emphasis"><em>plan</em></span>, <span class="emphasis"><em>PAR</em></span>, <span class="emphasis"><em>configuration</em></span>,
	<span class="emphasis"><em>Web Application Bundle (WAB)</em></span>, and <span class="emphasis"><em>WAR</em></span> artifacts, which enable
	you to build sophisticated web applications. This includes support for
	standard Java EE WARs, "shared library" WARs, and "shared services" WARs, each of
	which will be covered in greater detail in <a class="xref" href="ch03.html" title="3. Deployment Architecture">Chapter 3, <i>Deployment Architecture</i></a>.
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