How to create a scala based service daemon which can be called by a web app?

How could I write a service in scala such that a web application wo开发者_高级运维uld be able to call out to its endpoints?

How would it run as a daemon?

You could use Lift to build a REST-style web service. The Lift wiki explains it quite well.

You should take a look at BlueEyes and Scalatra if all you want is an efficient/scalable RESTful service, without the extra bells and whistles that Lift gives you.