In Milestone M5, for the first time, dm Kernel is available standalone. You can get it from here.

What is dm Kernel?

Basically, dm Kernel is everything good about dm Server except support for web applications. So, there are no web apps supplied (not even Admin Console or Splash) and no Tomcat —just the kernel.

Essentially, dm Kernel provides you with all that is good about dm Server’s OSGi support, including:

• scoping
• hot deployment
• pars
• bundles
• plans
• configuration properties
• auto-provisioning
• repositories
  • all repository types: watched, external and remote
  • chain support (the chain is empty by default)
• easy configurability
• the user region
• full system and application tracing and dump support
• oh, and of course, Spring beans and Spring DM support as usual,

but no web stuff.

If you want OSGi modular support for your system apps, but don’t want or need to host web applications, then dm Kernel is what you want.

This is exactly the same kernel that is shipped with a full dm Server—no modifications or adaptations. Being able to deploy and run the kernel by itself is yet another demonstration of the clean, modular design of dm Server.

Small print

How do I administer a dm Kernel without the Admin Console? (I can almost hear you ask.) Well, the answer is also provided in M5—use the Shell either locally or remotely (over ssh). You’d think we planned this, or something.

Enjoy.

(updated 15Oct2009) Beginning in milestone M5, dm Server 2.0 employs regions to isolate the kernel from users’ applications. This means that the kernel implementation is almost completely invisible to applications and to application management.

Also in milestone M5, support for cloning is completely removed. Region isolation and scoped plans between them offer much simpler and more manageable solutions to the most common problems that cloning was intended to address.

In the following two sections I outline these changes, and the reasons we made them.

The regional news

A Region is just like an OSGi framework—it is where applications are installed, resolved and run.

dm Kernel creates a single User Region in which to run applications and all applications (including the ones that dm Server supplies—Splash, Admin, Web and Hosted Repository) are deployed into the User Region…

In Rob's dm Server Roadmap blog entry, last April, we introduced two new artefact types: “plan” and “configuration file”.

Here is a short screencast demonstrating configuration files, in particular we show how to reference them from a plan.

First, a small web application picks up properties from a configuration properties file—deployed separately from the application. Second, the application and the properties are placed in the repository and a plan is constructed and deployed which installs and starts both the web application and its properties in one step.

Configuration Properties (5:59)

• QuickTime Screencast (42.9 MB)

Source Code

The repository configuration-properties in the samples project contains all the code shown in the demonstration.

Git - git://git.springsource.org…