Jan 21, 2010

Fast REST API prototyping with Crochet and Scala

I just finished committing the last changes to Crochet and tagged version 0.1.4vcli now publicly available on GitHub (http://github.com/xllora/Crochet). Also feel free to visit the issues page in case you run into question/problems/bugs.

Motivation

Crochet is a light weight web framework oriented to rapid prototyping of REST APIs. If you are looking for a Rails like framework written in Scala, please take a look at Lift at http://liftweb.net/ instead. Crochet targets quick prototyping of REST APIs relying on the flexibility of the Scala language. The initial ideas for Crochet were inspired while reading Gabriele Renzi post on creating the STEP picoframework with Scala and the need for quickly prototyping APIs for pilot projects. Crochet also provides mechanisms to hide repetitive tasks involved with default responses and authentication/authorization piggybacking on the mechanics provided by application servers.

Who uses Crochet?

Crochet was born from the need for quickly prototyping REST APIs which required exposing legacy code written in Java. I have been actively using Crochet to provide REST APIs for a variety of projects developed at the National Center for Supercomputing Applications. One of the primary adopters and movers of Crochet is the Meandre Infrastructure for data-intensive computing developed under the SEASR project.

Crochet in 2 minutes

Before you start please check you have Scala installed on your system. You can find more information on how to get Scala up and running here.

Get the latest Crochet jar from the Downloads section at GitHub and the third party dependencies.

Copy the following code into a file named hello-world.scala.

import crochet._
new Crochet {
    get("/message") { 
        "Hello, World!"
    }
} on 8080

Get your server up and running by running (please change the version number if needed)
```
$ scala -cp crochet-0.1.4.jar:crochet-3dparty-libraries-0.1.X.jar hello-world.scala
```

You just have your first Crochet API up and running. You can check the API working by opening your browser and pointing it to http://localhost:8080/message and you should get the message Hello World! back.

Where to go from here?

You will find more information on the Crochet wiki at GitHub. The wiki contains basic information as a QuickStart guide (which also includes how to deal with static content), descriptions of the basic concepts used in Crochet, and several examples that can get up and running fast.