Scala Cookbook

15.5. Creating Web Services with Scalatra

Problem

You want to be able to build new web services with Scalatra, a lightweight Scala web framework similar to the Ruby Sinatra library.

Solution

The recommended approach to create a new Scalatra project is to use Giter8, a great tool for building SBT directories for new projects.

Assuming you have Giter8 installed, use the g8 command to create a new project with a Scalatra template:

$ g8 scalatra/scalatra-sbt
organization [com.example]: com.alvinalexander
package [com.example.app]: com.alvinalexander.app
name [My Scalatra Web App]:
scalatra_version [2.2.0]:
servlet_name [MyScalatraServlet]:
scala_version [2.10.0]:
version [0.1.0-SNAPSHOT]:

Template applied in ./my-scalatra-web-app

When Giter8 finishes, move into the new directory it created:

$ cd my-scalatra-web-app

Start SBT in that directory, and then issue the container:start command to start the Jetty server:

$ sbt

> container:start
// a lot of output here ...
[info] Started SelectChannelConnector@0.0.0.0:8080
[success] Total time: 11 s, completed May 13, 2013 4:32:08 PM

Then use the following command to enable continuous compilation:

> ~ ;copy-resources;aux-compile
1. Waiting for source changes... (press enter to interrupt)

That command is nice; it automatically recompiles your source code when it changes.

The Jetty server starts on port 8080 by default. If you switch to a browser and go to the URL http://localhost:8080/, you should see some default “Hello, world” output, indicating that Scalatra ...