- Groovy is a dynamic language that runs on the Java Virtual Machine and has seamless integration with Java. - Grails is an open source web application framework built on Groovy that follows conventions over configuration (CoC) and don't repeat yourself (DRY) principles. - Grails uses conventions to define a model-view-controller (MVC) structure and provides dynamic scaffolding to generate basic CRUD operations for domain classes.

1. Agile Web Development with Groovy and Grails Carol McDonald, Java Architect

2. Objective Overview of the Grails Web Platform

3. Groovy Overview

4. What is Groovy? A dynamic language written for the JVM Generates byte code Java like syntax Easy learning curve for Java developers Seamless integration with Java A Groovy object is a Java Object Groovy application can create Java objects Java objects can create Groovy objects

5. A Valid Java Program import java.util.*; public class Erase { private List<String> filterLongerThan(List<String> strings, int length) { List<String> result = new ArrayList<String>(); for (String n: strings) if (n.length() <= length) result.add(n); return (result); } public static void main(String[] args) { List<String> names = new ArrayList<String>(); names.add(&quot;Ted&quot;); names.add(&quot;Fred&quot;); names.add(&quot;Jed&quot;); names.add(&quot;Ned&quot;); System.out.println(names); Erase e = new Erase(); List shortNames = e.filterLongerThan(names, 3); System.out.println(shortNames); } }

6. A Valid Groovy Program import java.util.*; public class Erase { private List<String> filterLongerThan(List<String> strings, int length) { List<String> result = new ArrayList<String>(); for (String n: strings) if (n.length() <= length) result.add(n); return (result); } public static void main(String[] args) { List<String> names = new ArrayList<String>(); names.add(&quot;Ted&quot;); names.add(&quot;Fred&quot;); names.add(&quot;Jed&quot;); names.add(&quot;Ned&quot;); System.out.println(names); Erase e = new Erase(); List shortNames = e.filterLongerThan(names, 3); System.out.println(shortNames); } }

7. The Groovy Way def names = [&quot;Ted&quot;, &quot;Fred&quot;, &quot;Jed&quot;, &quot;Ned&quot;] println names def shortNames = names.findAll{ it.size() <= 3 } print shortNames

8. Grails Overview

9. What is Grails? An Open Source Groovy MVC framework for web applications Principles CoC – Convention over configuration DRY – Don't repeat yourself Similar to RoR but with tighter integration to the Java platform

10. Why Grails? ORM layer can be overly difficult to master and get right A return to POJO and annotations in JPA but still lots of stuff to learn Numerous layers and configuration files lead to chaos Adoption of frameworks a good thing, but too often lead to configuration file hell Ugly JSPs with scriptlets and complexity of JSP custom tags Grails addresses these without compromising their benefits

11. Grails Technology Stack

12. How To Get Started Download Grails http://grails.org Configure Netbeans 6.5 Download Groovy http://groovy.codehaus.org Set GROOVY_HOME , GRAILS_HOME Add bin to your PATH $GROOVY_HOME/bin:$GRAILS_HOME/bin For command line

13. Using Grails

14. grails create-app Will be prompted for the name of the application Generate a directory structure for Grails source Additional libraries Configurations web-app IDE runs the &quot;grails create-app&quot; command Demo

15. Grails Directory Structure Application name Additional JARs Web application Grail source

16. Netbeans Grails Project Structure Project name Grail source Additional JARs Web application

17. Configure for MySQL copy the mysql-connector-java-5.1.6-bin.jar to the lib directory Edit DataSource.groovy dataSource { pooled = true driverClassName = &quot;com.mysql.jdbc.Driver&quot; username = &quot;root&quot; password = &quot;&quot; dialect = &quot;org.hibernate.dialect.MySQL5InnoDBDialect&quot; } environments { development { dataSource { dbCreate = &quot;update&quot; // one of 'create', 'create-drop','update' url = &quot;jdbc:mysql://localhost/petcatalog&quot; } }

18. MVC and Grails Models, or domain classes, represent the problem domain

19. grails create-domain-class The Model is your application's persistent business domain objects.

20. add the domain class attributes class Item { Long id String name String description String imageurl String imagethumburl BigDecimal price } Groovy with Grails dynamically generates getters and setters and the dynamic methods Item.save(), Item.delete(), Item.list(), Item.get() to retrieve/update data from/to the db table.

21. Persistence Methods GORM automatically provides persistence methods to your object save() , get() , delete() Automatically generates addTo * () for object relationships Where * is the name of the property def item = new Item(name:'Fred') def order = new Order(orderDate: new Date(), item: 'PSP') item. addToOrders (order) item. save ()

22. Queries Dynamically generated queries list , findBy Manual queries (not discussed here) HibernateQL Examples Item.list() Item.findBy Name ('nice cat')

23. grails domain class Define relation between objects with attributes hasMany , belongsTo static hasMany = [ item: Item ] Groovy hashmap Address String street String zip static hasMany = [item:Item] 1 M Item String name String description Address address

24. Scaffolding Generates CRUD actions and views for the corresponding domain class Dynamic: Enable the scaffold property in the controller class def scaffold = true Static grails generate-all Generates a controller and views for a domain class Useful to get up and running quickly

25. Scaffolding Generates a controller and views for the domain class Demo

26. MVC and Grails Controllers control request flow, interact with models, and delegate to views.

27. grails create-controller Controller made up of action methods Grails routes requests to the action corresponding to URL mapping Default action is index class Item Controller { def index = { redirect(action:list,params:params) } def list = { if(!params.max) params.max = 10 [ itemList: Item.list( params ) ] } def show = {... Actions http://host/catalog/item/list

28. URL Mappings Default mapping from URL to action method http://host/catalog/item/list Defined in grails-app/conf/UrlMappings.groovy static mappings = { &quot;/$controller/$action ? /$id ? &quot; Application Controller Action

29. grails controller class Item Controller { def index = { redirect(action:list,params:params) } def list = { if(!params.max) params.max = 10 [ itemInstanceList: Item.list ( params ) ] } def show = {... returns an ArrayList of item objects retrieved from the item database table itemInstanceList variable is made available to the view

30. MVC and Grails Views are defined in Groovy Server Pages (GSP) and render the model

31. grails view actions usually render a Groovy Server Page in the views directory corresponding to the name of the controller and action. list.gsp <html> <table> <tbody> < g:each in=&quot;${ itemInstanceList }&quot; status=&quot;i&quot; var=&quot; itemInstance &quot;> <td> ${fieldValue (bean: itemInstance , field:' price ')}</td> </tr> </g:each> </tbody> </table> g:each Groovy Tag loops through each object in the itemInstanceList variable displays the value of the item 's price attribute

32. grails run-app Will start the embedded web server and run the application Defaults to http://localhost:8080/<app_name> Demo

33. Summary Groovy is a powerful dynamic language for the JVM Grails is a full featured web platform

34. http://weblogs.java.net/blog/caroljmcdonald/

35. Acknowldegement Thanks to Guilaume Laforge of G2One for allowing me to use and adapt some of his slides

36. Presenter’s Name [email_address] Carol McDonald Java Architect Tech Days 2009

37. Lots of Books and Online Tutorials