Scala on Google App Engine

Eishay SmithKaChing

Who Am I

kaChing - Rocking the inventing world ! Scala @ LinkedIn Blogging http://www.eishay.comNewspipes

http://github.com/eishay/newspipeskaChing Twitter Bot

http://code.google.com/p/kaching-twitter/ Presented:

            "Absorbing Scala into Java Ecosystem"

Google App Engine

Run your web apps on Google's infrastructure. Easy to build, easy to maintain, easy to scale.  

Now with Java And a host of languages  that run on the JVM

JRuby, Groovy, Scala, Jython, ...

Tooling

EclipseGreat GAE support for Java with GWT and JDOSome problems coming to Scala

AntAll you needLonger development/test cycle

Oher IDEsNetbeansIDEA

Scala and Google Web Toolkit (GWT)

GWT - quickly build and maintain complex & performant JavaScript front-end apps written in Java (NOT Scala)

GWT actually compiles the Java source code A GWT class should not reference any Scala class

Still, GWT is super cool, use it! 

You can still have 99% of the server side in ScalaUse Java only for service interfacesUse Scala for the rest

Use interface

To buffer between Scala and GWT code

Implement using the best language

 

Use From GWT

 

One XML to bind them all

 

Regular HttpServlet

 

With Regular Binding

 

Scala @ JDO: Spelling it out

Similar to the Java JDOUsing the same annotations

Scala @ JDO: ANT

The ORM enhancer works on the class filesBytecode instrumentationDoes not matter if its Java or Scala

Scala @ JDO: Eclipse Support

Not really working since the IDE is looking for Java source files to instrumentThe solution is to use Eclipse Builders Have the ANT JDO builder building after compilationProvide an appengine.sdk path to the jar Eclipse use

More Limitations

Same limitations as in JavaIO librariesThreading

Can't open new threads => Actors in a same thread mode Lift on a single threaded Actor is happy

BuildingScalaScalac knows how to read java code !Needed for circular dependencies.

We Are Hiring !