Conceptually, VTS can be divided into two separate subsystems, one of which actually encompases the other:
- The kernel, which is the heart of VTS. It makes up most of the VTS, except for the part that supports Web applications. In other words, the kernel provides full OSGi modular support for your applications, as long as they are not Web-based.
See The Virgo Kernel for additional information.
- The user region is the subsystem that manages user applications. It deliberately isolates the kernel from both your applications and those of the VTS itself, such as the Admin Console, making it much easier for you to administer VTS.
See The User Region for additional information.
When you download and install Virgo Tomcat Server you get both the kernel and web server support (configured in the user region). You can also download and use the kernel on its own if you do not plan on deploying Web applications or using the web-based Admin Console and you'll get the kernel and a minimal user region (with no web support).
The following graphic shows how the kernel and user region make up VTS:
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The Virgo Kernel encapsulates almost all of VTS except for the deployment of Web applications. In sum, the kernel provides the following VTS features:
Deployment of non-Web artifacts, such as OSGi bundles, PARs, plans, and configuration artifacts.
Local and hosted repositories
Scoping
Hot deployment
User region
Auto-provisioning
System and application tracing and dump support
Spring beans and Spring DM support
See Configuring VTS for details about configuring the kernel to better suit your environment.