For a little educational project intended as a community resource to help people learn Scala I am looking for a simple way to serve and process web pages in a background thread.
Minimal background: Scalatron is a multi-player game in which players pit bot programs (written in Scala) against each other. It is accompanied by a step-by-step Scala tutorial. Currently players need to use an IDE on their local machines to compile bots, which are then published into the game by copying them into a shared network directory. This is cumbersome. For the next version it would be nice to offer browser-based bot editing and publishing to maximally simplify the setup for both organizers and players.
I already got a background thread working that will compile Scala source code arriving on the server on the fly (obviating the need for a full IDE). Next I have to run a tiny web server to provide an access point for players and to handle bot uploads (this gets rid of the network share).
The requirements are very basic: initially I envisage serving a single page with an edit box and a “Go” button (= upload to server, compile & publish into game); I expect no more than 20 concurrent users with not more than one bot upload across all users every 5 or 10 seconds; I need to hold minimal state for each users (just a name) and I need to return compiler error messages to the user. Note that game screen updates would NOT be displayed in the browser but on a projector attached to the server machine. And primarily to allow for the simplest possible setup (double click on the game server .jar) I think it would be nice to run the web server in a background thread within the existing game server.
What is the most appropriate way to do this? Should I use some existing framework, like Play or Lift? Is there existing code for doing something very similar to this? Is it even reasonable to plan to run a web server in a background thread like this? Any advice is appreciated.
One of the most used small, embeddable web servers / servlet containers in the Java world is Jetty. Since Scala can easily use Java libraries, it should be easy to use this from Scala.
This page shows some simple examples (in Java) on how to start it as an embedded HTTP server.