Alphageeks IL #2 Groovy & Grails

Groovy & Grails(also) the future of Java Web Development
Yuval Goldstein,
yuvalgo@gmail.com,
@yuvalgo

Groovy, Grails, Agenda
Beyond Java
What’s groovy?
What’s grails?
How people use them?

Beyond Java
Java= Language + Classes +JVM
JEE = Robust spec to support server-driven apps
The good: OO, popular, tons of frameworks, enterprise ready (queues, transactions, web-services)
The Bad: Verbose, long turn-around, mix and match your own framework

Beyond Java
Java code > compiled into bytecode > JVM
The JVM supports other languages:
Groovy
Scala
JRuby
Jython
But WHY? : Because not every problem should be solved by a general purpose language

Groovy
Cool language, compiles into bytecode
Similar to Java, a lot of additions and improvements:
Language level support for collections
Closures and Builders
Dynamic typing
Concise syntax
Groovy2Java, Java2Groovy integration

Demo
Let’s take a Java class and show how it’s done in Groovy

Closures
A piece of code that can be passes around and executed (sort of an Anonymous class with a method)

More Closures

Demo
Let’s see some Collections and Closures working together

Groovy typing
Types can be specified and enforced
Types can unspecified and deducted (Duck Typing)

Duck Typing
Behavior of objects is determines by their own methods and members rather than by declarations

Duck Season? - Demo
Let’s see how duck typing works

Duck Typing
Sacrifice certainty for laziness, WTF?
Some application really need strict typing, other doesn’t
Frameworks generate a lot of code for you on runtime
Faster code changes
Good testing really helps
You already doing it:
HTML, CSS, SQL, JSP

Expando Classes

String Matching

Introducing Grails
Grails=Groovy + Spring + Hibernate + Sitemesh
A framework for developing web-apps with pleasure
Open-Source, supported by Spring-Source
Convention over configuration
Model-driven
Short turnaround
Good developer-testing support
A lot more…

Demo
Create an empty application
Develop a domain classes
Generate a trivial CRUD : dynamic, then static

Domain Objects and GORM
GORM: Hibernate DSL
1:1, 1:N, M:N, Object hierarchies, Versioning, Cascade, Fetch
Objects are DAOs
Automatic Query Syntax:
Object.save()
Object.get(id)
Object.findAll()

Controllers
Each closure maps to a request name
Render templates, GSP, XML, JSON
Automatic variables: param, session, flash
Support Spring Webflow
Dependency Injection support (for services)

Views
GSPs, taglibs, Templates
HTML centric
Built in Tags for: Forms and error handling , AJAX, Pagination, uploads
Pluggable Ajax support: Prototype, YUI, others
Plugins: Grails-UI, Flex, GWT, Open Lazzlo, Portlet integration

Services
Help re-use code, scope transaction, expose web-services
Different Scopes: singleton, session, prototype, request, conversation, flow
Dependency Injection support
Plugins: JMS integration, Quartz Jobs, Xfire/Spring web-services, etc…

Testing support
Built-in Unit and Integration testing
Good mockup support
Can’t do without it

(Only some) Plugins
GrailsUI
Acegi Security
Twitter
Flex
Quartz
Searchable

Groovy, Grails in the wild
Groovy:
As a scripting tool for developers
For testing plain java code
For developing swing code (special DSL)
For coding grails application
Grails:
Prototypes and back-office applications
Grails Frontend with Java backend
Grails frontend and backend

Community and support
Open-Source, use for free
Commercial training and support by spring
Grails user newsgroup on Nabble: 40-80 messages a day
IDEs: Eclipse, Intellij, Netbeans, TextMate
Books:Groovy in action, Grails in Action, Definitive Guide to Grails, Getting started with Grails, Groovy & Grails Recepies, more…
Sites:grails.org, aboutgroovy.com, grailspodcast.com, grailstutorials.com

Who use Grails?
Linkedin.com
Sky.com
twitcaps.com
blerp.com
twitsms.co.uk
Ganttzilla.com
Lot’s of community, e-commerce and twitter oriented sites

Summary
Grails is ideal for small and medium size application
Grails ~= Rails capabilities + JVM + All existing Java frameworks
0 Setup development environment
Fun to use

Thanks !