![Closures
• Syntax
• Must be enclosed by curly braces “{ }”
• May take a list of optional arguments
separated by “,”
• The symbol “->” separates args from body
• “it” represents single arg (-> not required)
{ [optional args ->] zero or more statements }
36](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-35-320.jpg)
![Why Groovy?
• Example:
• Define Todo Class
• Create list public class Todo {
Todo.groovy
String name
• Add 3 todo’s }
String note
• Print List def todos = [
new Todo(name:"1", note:"one"),
new Todo(name:"2", note:"two"),
new Todo(name:"3", note:"three")
• Groovy: 12 LOC ]
todos.each {
println "${it.name} ${it.note}“
}
40](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-39-320.jpg)
![Why Groovy?
• Java: 45 LOC Todo.java
import java.util.List; public void setNote(String note) {
import java.util.ArrayList; this.note = note;
import java.util.Iterator; }
public static void main(String[] args){
public class Todo { List todos = new ArrayList();
private String name; todos.add(new Todo("1", "one"));
private String note; todos.add(new Todo("2", "two"));
public Todo() {} todos.add(new Todo("3","three"));
public Todo(String name, String note){
this.name = name; for(Iterator iter =
this.note = note; todos.iterator();iter.hasNext();){
} Todo todo = (Todo)iter.next();
public String getName() { System.out.println(todo.getName() +
return name; " " + todo.getNote());
} }
public void setName(String name) { }
this.name = name; }
}
public String getNote() {
return note;
}
41](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-40-320.jpg)
![Dynamic Finders
• Looks like a static method invocation
• methods do not exist in the code
• generated at runtime based on class properties
def spkr = Speaker.findByFirstName(“Jhon”)
def spkr = Speaker.findByFirstNameAndLastName(“Jhon”, “Smith”)
def spkrs = Speaker.findByAllFirstNameLike(“J%”)
def spkrs =
Book.findAllByTitleLike(“J%",
[max:3, offset:2, sort:"title", order:"desc"])
54](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-53-320.jpg)
![Models and Views
• Returning the model
• a model is a map used by view to render
response
Explicit model map return
class BookController {
def show = {
[ book : Book.get( params.id ) ]
}
Controller properties used as model
class BookController {
List books
List authors
def list = {
books = Book.list()
authors = Author.list()
}
}
58](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-57-320.jpg)
![Models and Views
• Selecting the View
• implicit using conventions
• explicit using render
Implicit
class BookController {
def show = {
[ book : Book.get( params.id ) ]
}
}
/app-name/views/book/show.gsp
Explicit
class BookController {
def show = {
def map = [ book : Book.get( params.id ) ]
render(view:"display", model:map)
}
/app-name/views/book/display.gsp
59](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-58-320.jpg)
![Data Binding
• Binding Request Data to the Model
• Based on Spring’s binding
/book/save?book.title=The_Stand&author.name=Stephen_King
class BookController {
def save = {
def b = new Book(params[„book‟]) //implicit constructor
def a = new Author(params[„author‟]) //implicit constructor
a.addToBooks(b)
a.save()
}
def update = {
def b = Book.get(params.id)
b.properties = params
b.save()
}
}
60](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-59-320.jpg)
![Templates
• By convention _<view name> is a template
• can be rendered from a view or controller
grails-app/views/book/_bookTemplate.gsp
<div class="book" id="${book?.id}">
<div>Title: ${book?.title}</div>
<div>Author: ${book?.author?.name}</div>
</div>
grails-app/views/book/list.gsp
<g:render template="bookTemplate" model="[book:myBook]" />
<g:render template="bookTemplate" var="book“
collection="${bookList}" />
64](https://image.slidesharecdn.com/javaedge2009grailswebdevmadeeasy-12865774388426-phpapp01/85/Java-Edge-2009-Grails-Web-Dev-Made-Easy-63-320.jpg)
Java Edge.2009.Grails.Web.Dev.Made.Easy
- 1. Grails Web development made easy By: Roi Aldaag, Consultant & Architect
- 2. Agenda • Introduction • Demo • Groovy 101 • Grails • Google App Engine (GAE) 2
- 3. Introduction
- 4. Introduction • What is Grails? • Architecture • Grails Goals 4
- 5. What is Grails? • A full stack web framework • Open Source (Apache 2.0 license) • Based on Groovy • Fully compatible with Java 1.0 1.1.1 Release Release 2005 2006 02/2008 11/2008 2009 5
- 6. Architecture Grails Groovy Java EE Spring Hibernate SiteMesh The Java Development Kit The Java Language (JDK) The Java Virtual Machine 6
- 7. Design Goals / NYAJWF Full Stack Productivity Convention / Configuration Grails Agile Community Philosophy Java Solid Integration Foundations 7
- 8. Design Goals / NYAJWF • Full stack • Grails comes with a full development environment • Web server (Jetty / Tomcat) • Database (HSQLDB) • Testing (JUnit) • Command line shell • Grails console 8
- 9. Design Goals / NYAJWF • Convention / Configuration • Sensible defaults based on source code • Defaults can be overriden with no XML • Existing XML configurations can still be used 9
- 10. Design Goals / NYAJWF • Agile philosophy • Development is an interactive process • Add / modify Controllers, Domains and Views while application is running • Refresh view to test results • Zero turn-around • No deployment / server restart required • Rapid prototyping • Scaffolding 10
- 11. Design Goals / NYAJWF • Solid foundations • Built on tested and proven OS technologies • Spring framework • Hibernate ORM • SiteMesh page layout framework • AJAX libraries: script.aculo.us, Rico, prototype • HSQLDB • Junit • Minimizes learning curve • Backed up by SpringSource 11
- 12. Design Goals / NYAJWF • Java Integration • Groovy code is compiled to bytecode • Java code can be run as Groovy* • GDK -> Groovy’s extention to JDK (~ 60 enhanced classes) • GroovyClassLoader • Loads and parses Groovy classes to be used in Java classes 12
- 13. Web framework made easy Web frameworks in Java don’t have to be: 13
- 14. Web framework made easy • Frustrating 14
- 15. Web framework made easy • Slow 15
- 16. Web framework made easy • and cause you a nervous breakdown… 16
- 17. Web framework made easy • With Grails it can be like this: 17
- 18. Web framework made easy • Or maybe more like this … 18
- 19. Design Goals / NYAJWF • Productivity • Development is fun! • Develop web applications much quicker • Concentrate on business model • Get instant feedback • No XML configuration • Ready to use development environment 19
- 20. Demo Let Grails do the magic …
- 21. Demo • So here is the initial Mockup… 21
- 22. Demo • Ingredients: 1. a handful of images 2. a pinch of mockup data 22
- 23. Demo • More ingredients… 3. Five domain classes + Five controller classes 23
- 24. Demo • and let Grails do the magic… 24
- 25. Demo • It’s DEMO time! 25
- 26. Statistics 26
- 27. Demo • … and we are done! 27
- 28. Groovy 101 Quick Groovy crash course
- 29. Groovy 101 • OO dynamic programming language • A superset of the Java language • Works seamlessly with Java libraries • Most Java Code is syntactically valid Groovy • Compiled to JVM bytecode • Used as a scripting language for the JVM James Strachan's JSR 241 1.6.5 Release Weblog 1.0 Release 2003 2007 2009 29
- 30. Groovy 101 • Compilation • precompiled • direct JVM 30
- 31. Groovy 101 • Differences from Java (partial list) • GDK extends JDK (e.g. GString) • Parenthesis and Semicolons are optional • Implicit return, getters and setters • Anonymous inner classes not supported • == equality not identity • Default access of “public” • Only runtime exceptions 31
- 32. Groovy 101 • Features (very partial list…) • Dynamic typing • Closures • Operator Overloading • Native support for RegEx • Native support for markup languages • Native support for testing (JUnit) • Expressions embedded inside strings 32
- 33. Dynamic Typing • Use def keyword when defining variables (optional) • At runtime, the appropriate type will be used based on assigned value def var = 1 assert var.class in java.lang.Integer var = “Hello World” assert var.class in java.lang.String 33
- 34. Closures • What is a closure? • An anonymous block of code • Do not have to be declared in a class • An object of type groovy.lang.Closure • Assigned to variables • Passed as method arguments • Can reference variables within their scope • Executed when it’s called—not when it’s defined 35
- 35. Closures • Syntax • Must be enclosed by curly braces “{ }” • May take a list of optional arguments separated by “,” • The symbol “->” separates args from body • “it” represents single arg (-> not required) { [optional args ->] zero or more statements } 36
- 36. Closures • Definition {println “Hello World!”} // no args {message -> println message} // untyped arg {arg1, arg2 -> return arg1 + arg2} // untyped args {println it} // implicit arg • Assignment & Call def p = {println it} // assign p(“Hello World!”) // call 37
- 37. Expressions embedded inside strings (1/2) • GString evaluates expressions embedded within the string • Expression is evaluated when string is accessed • Uses ${...} notation • “…” – evaluated ‘…’ – not evaluated 38
- 38. Expressions embedded inside strings (2/2) def str = “JavaEdge2009" def hello = "Hello, ${str}" println hello // Hello JavaEdge 2009 println hello.class.name // org.codehaus.groovy. // runtime.GStringImpl def hello = „Hello, ${str}‟ println hello // Hello, ${str} println hello.class.name // java.lang.String 39
- 39. Why Groovy? • Example: • Define Todo Class • Create list public class Todo { Todo.groovy String name • Add 3 todo’s } String note • Print List def todos = [ new Todo(name:"1", note:"one"), new Todo(name:"2", note:"two"), new Todo(name:"3", note:"three") • Groovy: 12 LOC ] todos.each { println "${it.name} ${it.note}“ } 40
- 40. Why Groovy? • Java: 45 LOC Todo.java import java.util.List; public void setNote(String note) { import java.util.ArrayList; this.note = note; import java.util.Iterator; } public static void main(String[] args){ public class Todo { List todos = new ArrayList(); private String name; todos.add(new Todo("1", "one")); private String note; todos.add(new Todo("2", "two")); public Todo() {} todos.add(new Todo("3","three")); public Todo(String name, String note){ this.name = name; for(Iterator iter = this.note = note; todos.iterator();iter.hasNext();){ } Todo todo = (Todo)iter.next(); public String getName() { System.out.println(todo.getName() + return name; " " + todo.getNote()); } } public void setName(String name) { } this.name = name; } } public String getNote() { return note; } 41
- 41. Grails Setup
- 42. Setup Install JDK http://java.sun.com/ Install Grails http://www.grails.org Customize Environment GRAILS_HOME=/opt/grails Add Grails to PATH PATH=$GRAILS_HOME/bin;$PATH 43
- 43. Tools • IDE integration • Eclipse plugin • IntelliJ 8 built in support • NetBeans 44
- 44. Tools • Grails Console • run Groovy Scripts • test Domain classes 45
- 45. Tools • Grails Shell • create scripts • domain, controller, view • create and run tests • unit tests • integration test • deploy application • start server 46
- 46. Grails Features
- 47. Grails Features • Model • Application Flow • Presentation • Scaffolding • Testing • Plug-Ins 48
- 48. Model • GORM • Domain classes • Basic CRUD • Finders 49
- 49. GORM (Grails ORM) • Simplifies data access • Uses Groovy’s dynamic typing • Injects CRUD methods into the domain class • Provides dynamic finder methods • Eliminates boiler plate code implementation • No required inheritance from a persistent class • Based on Hibernate 3 50
- 50. Basic Domain Creation • Create a new domain class app-dir> grails create-domain-class speaker class Speaker { static constraints = { } } 51
- 51. Basic Domain Creation • Customize class class Speaker { String firstName String lastName String company String title static constraints = { firstName(maxSize: 20) lastName(maxSize:20) title(maxSize:50) } optimistic locking } 52
- 52. Basic CRUD Create def spkr = new Speaker(firstName: ”Jhon”, lastName: “Smith”, title: “Consultant”) spkr.save() Read def spkr = Speaker.get(id) Update def spkr = Speaker.get(id) spkr.title = “Architect” spkr.save() Delete def spkr = Speaker.get(id) spkr.delete() 53
- 53. Dynamic Finders • Looks like a static method invocation • methods do not exist in the code • generated at runtime based on class properties def spkr = Speaker.findByFirstName(“Jhon”) def spkr = Speaker.findByFirstNameAndLastName(“Jhon”, “Smith”) def spkrs = Speaker.findByAllFirstNameLike(“J%”) def spkrs = Book.findAllByTitleLike(“J%", [max:3, offset:2, sort:"title", order:"desc"]) 54
- 54. Application Flow • Controllers • Models and Views • Data Binding 55
- 55. Controllers • Handles requests • Creates or prepares the response • A new instance created for each request • Default URL Mapping: controller params.id name /app-name/speaker/update/id application action name name 56
- 56. Controller Creation • Create a new controller app-dir> grails create-controller speaker class SpeakerController { def index = { } def actionName = { // do controller logic // create model return model } def defaultAction = “actionName" } 57
- 57. Models and Views • Returning the model • a model is a map used by view to render response Explicit model map return class BookController { def show = { [ book : Book.get( params.id ) ] } Controller properties used as model class BookController { List books List authors def list = { books = Book.list() authors = Author.list() } } 58
- 58. Models and Views • Selecting the View • implicit using conventions • explicit using render Implicit class BookController { def show = { [ book : Book.get( params.id ) ] } } /app-name/views/book/show.gsp Explicit class BookController { def show = { def map = [ book : Book.get( params.id ) ] render(view:"display", model:map) } /app-name/views/book/display.gsp 59
- 59. Data Binding • Binding Request Data to the Model • Based on Spring’s binding /book/save?book.title=The_Stand&author.name=Stephen_King class BookController { def save = { def b = new Book(params[„book‟]) //implicit constructor def a = new Author(params[„author‟]) //implicit constructor a.addToBooks(b) a.save() } def update = { def b = Book.get(params.id) b.properties = params b.save() } } 60
- 60. Presentation • GSP • Grails Tags • Templates • Layouts 61
- 61. GSP (Grails Server Pages) • Similar to JSP and ASP • A mix of markup and GSP tags • Uses model passed from Controller to render view • GSP pages reside in “/grails-app/views” directory • Supports scripting of Groovy (discouraged) • Supports GSP expressions within “${ }” 62
- 62. GSP Tags • Built-in GSP tags • start with g: prefix (no tag library imports) • attributes can be expression or maps • control flow operations like in JSTL • Tags as method calls • GSP tags can be called as methods from controllers, tag libraries or GSP views <img src="<g:resource dir="images" file="logo.jpg" />" /> <img src="${resource(dir:'images', file:'logo.jpg')}" /> def imageLocation = g.resource(dir:"images", file:"logo.jpg") 63
- 63. Templates • By convention _<view name> is a template • can be rendered from a view or controller grails-app/views/book/_bookTemplate.gsp <div class="book" id="${book?.id}"> <div>Title: ${book?.title}</div> <div>Author: ${book?.author?.name}</div> </div> grails-app/views/book/list.gsp <g:render template="bookTemplate" model="[book:myBook]" /> <g:render template="bookTemplate" var="book“ collection="${bookList}" /> 64
- 64. Layouts • Based on Sitemesh • a web-page layout and decoration framework • decorates response and applies a consistent L&F • uses composite pattern • Layouts are located in grails-app/views/layouts Specifying a Layout in a Controller grails-app/views/layouts/customer.gsp class BookController { static layout = 'customer' } 65
- 65. Services • A class that ends with the convention “Service” • Re-use business logic across application • Controllers should handle request flow and redirects • Manages transaction demarcation app-dir> grails create-service simple class SimpleService { boolean transactional = true def serviceMethod() { } } 66
- 66. Dependency Injection • Use the property name representation of a service to inject it to a Controller / Domain class • Based on Spring Framework's dependency injection capability class BookController { def bookService //BookService … } class Book { … def bookService //BookService def buyBook() { bookService.buyBook(this) } } 67
- 67. Scaffolding • auto-generate a whole application for a given domain class including • GSP views • Controller actions for CRUD operations • Database schema • uses introspection • dynamic scaffolding is generated at runtime • static scaffolding is generated in source code class BookController { def scaffold = true } 68
- 68. Testing • Unit tests • Grails does not inject dynamic methods • no DB support • based on JUnit • extends GrailsUnitTestCase • provides mocking support (EasyMock): mock*() • uses assert*() app-dir> grails create-unit-test speaker app-dir> grails test-app -unit speaker 69
- 69. Testing • Integration tests • executes inside a full Grails environment • runs against a live database • uses Mock versions of the servlet request, response, and session • transaction is rolled back at the end • supports URL mappings app-dir> grails create-integration-test speaker app-dir> grails test-app speaker 70
- 70. Plug-ins • Core plugins • GORM, Controllers, WebFlow, etc. • Custom plugins • Grails Plugin Repository • http://grails.org/plugin/home • per project / global app-dir> grails list-plugins app-dir> grails install-plugin <plugin-name> 71
- 71. Performance • The bad • Dynamic is slower than static • Many abstraction layers • The good • Bottleneck is usually I/O not CPU • JDK 7 (JSR 292) • OpenJDK: Da Vinci Project 72
- 72. Google App Engine Start your engine …
- 73. Google App Engine • A platform for developing and hosting web applications in Google-managed data centers • Virtualizes applications across multiple servers and data centers (cloud computing) beta 1.0 Release 1.2.7 Release 2007 2008 2009 74
- 74. Google App Engine • Free up to a certain level of resources • Fees are charged for additional storage, bandwidth, CPU • Supports: Python and JVM languages (Java, Groovy, JRuby, Scala, Clojure) 75
- 75. Grails on AppEngine • Groovy 1.6.1 runs on AppEngine • Grails 1.1.1 adds official support • Grails AppEngine Plugin • Replaces Hibernate with JDO (soon JPA) • Integrates with AppEngine dev environment and deployment tools 76
- 76. References • Grails • http://www.grails.org/Documentation • http://old.nabble.com/grails---user-f11861.html • Groovy • http://groovy.codehaus.org/ • http://groovymag.com/ • Google App Engine • http://code.google.com/appengine/ • http://grails.org/plugin/app-engine • http://groups.google.com/group/google-appengine- java/web/will-it-play-in-app-engine?pli=1 77
- 77. Documentation • Internet • http://grails.org/Documentation • Books • 9 books on Amazon! 78