See http://blog.nodejs.org/2011/03/23/npm-1-0-global-vs-local-installation

For modules you use in the shell, npm install -g is the way to go, but if you're using a module in an application by requireing it, it should be installed locally (that is to say, without -g

I also did not get aphlict to run by only installing ws globally. I had to install it locally, in support/aphlict/server - which was the second option the docs, but probably is the only option that works reliably.