Inline C can offer more than just simple extensions. I've extended Varnish 2.1.* to include a custom authentication layer that basically means I can drop multi

Inline C can offer more than just simple extensions. I've extended Varnish 2.1.* to include a custom authentication layer that basically means I can drop multiple different applications behind Varnish and have the equivalent of a Web Account (of the ilk of Google Account, Yahoo Account, etc). The functions provided by the shared library I've written require a whole load of VCL to grab hold of parts of the cookie and to pass things into the functions, before then handling the return values and re-writing headers (that the backend servers then look for). It all works really well, and I haven't found VCL to be an ugly domain specific language to work with, especially when you consider that it translates directly to C which is then compiled. When I think of what it took to write an Nginx mod, VCL with Inline C is a dream.