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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 Web 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 Web 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 Web Server?</h2></div></div></div><p> | |
| The Virgo Web Server, or VWS for short, is the runtime portion of the Virgo Runtime Environment. | |
| 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 VWS 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 Web Server?</h3></div></div></div><p> | |
| The Virgo Web 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 R4.2</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 Web 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 VWS’s architecture. | |
| </p><p> | |
| <img src="images/introduction-architecture.png"> | |
| </p><p> | |
| At the heart of the Virgo Web 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 VWS. | |
| </p><p> | |
| To maintain a minimal runtime footprint, OSGi bundles are installed on demand by the | |
| VK provisioning subsystem. This allows for an application to be installed into a running | |
| VWS 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 is a layer of subsystems which contribute functionality | |
| to the VWS. Subsystems typically provide additional services to the basic OSGi container | |
| such as serviceability, management, and specific artifact deployment such as web application. | |
| </p><p> | |
| Version 2.1.1.RELEASE of the Virgo Web 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</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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