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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">5.2 The User Region</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch05.html">Prev</a> </td><th width="60%" align="center">5. Overview of the Virgo Kernel and User Region</th><td width="20%" align="right"> <a accesskey="n" href="ch06.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="user-region-overview"></a>5.2 The User Region</h2></div></div></div><p> | |
| The user region isolates the kernel from deployed applications, | |
| including both your own user applications and the user-oriented | |
| VWS applications such as the Admin Console. This means | |
| that the kernel is mostly invisible to applications and to application | |
| management. This is because most of the kernel bundles are not | |
| installed in the user region (apart from a few needed for region | |
| management). The necessary function to support the kernel runs in the | |
| OSGi framework, but the user region applications cannot see it, except | |
| for the services that are normally offered. | |
| </p><p> | |
| This way of implementing VWS greatly simplifies | |
| the administration tasks you perform. In particular, when you use the | |
| Admin Console to manage Web Server, you do not see | |
| the many bundles that are internal to the kernel. The only exceptions | |
| are the kernel bundles that VWS uses for region | |
| management, which are required to be installed in the user region. | |
| </p><p>This isolation has many other benefits. For example, it is no longer necessary for the kernel and user applications to use the same version of the Spring Framework. In fact the kernel installs only those parts of the Spring Framework that it needs. If you update the kernel, it is far less likely that you will also need to upgrade or adjust the applications to accomodate a new version of the kernel. The kernel implementation is therefore much more stable and resilient and applications are much more likely to survive kernel upgrades between releases. </p><p>When you install VWS, the kernel creates a single user region. | |
| The kernel and the user region are configured independently of each other; see <a class="link" href="ch11.html" title="11. Configuration">Configuring VWS</a> for details. | |
| </p><p>Finally, the isolation provided by the user region together with scoped applications and plans solve common dependency problems that occur when using OSGi. </p></div><!--Begin LoopFuse code--><script src="http://loopfuse.net/webrecorder/js/listen.js" type="text/javascript"></script><script type="text/javascript"> | |
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