JKernel overview

The J-Kernel is a portable, Java-based system that extends the underlying Java Virtual Machine (JVM) to provide multiple protection domains and well-defined communication channels between the domains. The primary target application domain for the J-Kernel is customizable servers. The J-Kernel can be built into services to allow users to up custom extensions into them in a secure yet flexible manner. Just as Java currently allows content providers to safely download applets into Web browsers, the J-Kernel allows users to safely upload code into Internet servers.

The J-Kernel core is written entirely in Java and relies on properties of the language, on custom class loaders, and on "on-the-fly" bytecode rewriting techniques to implement multiple protection domains. The core runs on Sun's VM as well as on Microsoft's.

Documentation:

• The J-Kernel Tutorial comes in four parts and demonstrates how to run the kernel, how to write simple tasks. It also explains how tasks, capabilities, and class resolvers work.
• The J-Kernel API is JavaDoc generated documentation for the API exported by the J-Kernel to developers.
• The J-Kernel internals is also JavaDoc generated documentation but for all classes forming the J-Kernel, including the internal ones. This JavaDoc also contains links to the source code.

More background information can also be found in our Usenix 98 paper. Some changes in the API have been made since the paper was published. In particular, what the paper called "protection domains" are now called "tasks", because the term "protection domain" is used by other systems with different meanings.