At the moment, the mruby handler API is based on mod_mruby / ngx_mruby, which is based on the handler API of the Apache HTTP server. However, the API is unfamiliar to developers (compared to the huge number of users familiar with Ruby). It is also hard to maintain compatibility as we add features to the handler. OTOH, Rack exists as a very popular API for writing HTTP handlers. It is well-known, w