Building the Module

Overview

For those of you with a daring side to your personality, this chapter introduces Resin HardCore. Written as a Linux kernel module, Resin HardCore brings Web server functionality directly into the Linux kernel for handling HTTP requests with very little overhead.

We cannot stress enough that the techniques we discuss in this chapter are experimental. The kernel module supports only GET HTTP requests, logging, load balancing, and caching. Other major features aren't supported, and if there is a failure in the module, you risk crashing your entire Linux system.

The module works by forwarding all HTTP GET requests to an appropriate Resin servlet engine. The servlet engine is responsible for executing the request and returning the results to the module. Since the module is running in kernel space, the initial processing of the request and transfer to the servlet engine is very fast. Unlike a traditional Web server, though, the module does not do any page processing. The module is an ideal candidate for an easy-to-build load balancer.