Grails 0.6 Released with Rich Conversation Support (AKA Spring Web Flow)

We've just released Grails 0.6 which takes Grails even further away from its Rails-like beginnings. Thanks to integration with the Spring Web Flow project and support for Spring scopes Grails now supports rich conversations a la Seam.

The essence of it is that we have created a Groovy builder for construction Web Flows. This is both a good thing for Grails and for the Web Flow project as the current mechanism for flow definition in Web Flow is via XML which has limited expressiveness and too many angles for my liking.

An example of a Grails Flow can be seen below:

 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"
 }

Web Flow will completely manage the state transitions and Grails integrates Hibernate into the picture to make sure you get atomic conversations.

You can also encapsulate business logic inside service classes and define services as living in a particular scope:

class BookService {
   static scope = "flow"
   ...
}

Thus allowing conversations with a particular service scoped to individual clients. It is all rather exciting stuff and extends Grails' capabilities allowing much more complex workflows.

This is not the only exciting feature in Grails 0.6. The headliners are:

* 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 tools

Checkout the full release notes for details and download here