I was thinking a bit different. To extend compatibility to other service, I plan to let service to create their own handler. Like we could have a rabbitmq_proxy.rb says

    class ServiceMgmt
       post '/rabbitmq' do
           ...
       end
     end

And this file requires 'rabbitmq_proxy.rb' . The reason is the service may have to do more than extracting parameters. Like rabbit set cookie here is for auto-login the native UI. But this only works for 3.0 but not rabbit 2.8. While other services may have different plan here.