Grails 0.6 Adds Best of Breed Mix From Spring Web Flow and Rich Conversations a la JBoss

Graeme Rocher announced that Grails is moving further away from "its Rails-like beginnings" with this latest release.  Although this release was labeled as 0.6, it's clearly being modest with the amount of work that went into it. Here's the full feature list:

• Joint Groovy/Java Compilation
• Spring Web Flow Integration
• Support for Spring scopes to allow scoped services
• Improved support for REST with automatic XML/JSON marshalling and RESTful URL mappings
• New Config DSL for configuration not possible by convention
• Refreshed scaffolding interface and branding
• Support for Sitemesh inline decorators
• Controllers can now call tag libraries as methods
• New GSP tags
• Massive improvements to speed of start-up time, unit tests and generation tool

Spring Web Flow Integration

Just as Rod Johnson had proposed a new way of defining Spring-managed beans via code rather than the traditional XML markup, Graeme takes a similar approach by defining Spring Web Flow definitions with Groovy:

showCart {
    on("checkout").to "enterPersonalDetails"
    on("continueShopping").to "showCatalogue"
 }                                         
 enterPersonalDetails {
  on("submit") {
   def p = new Person(params)
   flow.person = p 
   def e = yes()
   if(p.hasErrors() || !p.validate())return error()    
  }.to "enterShipping"   
  on("return").to "showCart"
  on(Exception).to "handleError"
 }              
 enterShipping  {
  on("back").to "enterPersonalDetails"
  on("submit") {
   def a = new Address(params)                           
   flow.address = a
   if(a.hasErrors() || !a.validate()) return error()    
  }.to "enterPayment"
 }

The above snippet illustrates the concept of defining a unit of work or "conversation", as described in the JBoss Seam framework. Just as in Seam, the "flow" contains conversational state information.

Automatic XML/JSON marshalling and RESTful URL mapping

While previously using a plug-in for conversions, this release uses:

 import grails.converters.*
...

def list = {
    render Book.list() as XML
    // or render Book.list() as JSON
}