2006 JavaOne SM Conference | Session BOF-2521 | Rapid Web Application Development with Grails Graeme Rocher Managing Director Agilize it Session ID# BOF-2521

2006 JavaOne SM Conference | Session BOF-2521 | 2 Learn how to rapidly create web applications using the agile web application framework Grails Rapid Web Application Development with Grails Goal of this Talk

2006 JavaOne SM Conference | Session BOF-2521 | 3 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 4 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 5 Groovy & Grails ● Grails: MVC web framework inspired by: ● Convention over Configuration ● Don’t Repeat Yourself (DRY) ● Ruby on Rails ● Built on solid foundations: ● Spring IoC, MVC and WebFlow ● Hibernate ● SiteMesh ● Why Groovy? ● Meta-Programming ● Closure Support ● Syntactically Expressive ● Java Integration Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 6 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 7 Getting Started ● Grails available from ● Stable & Development snapshots available ● Simple installation: ● Download & extract zip ● Set GRAILS_HOME variable ● Add $GRAILS_HOME\bin to PATH variable ● Run “grails create-app” Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 8 + PROJECT_HOME + grails-app + conf + controllers + domain + i18n + services + taglib + views + lib + spring + hibernate + src + web-app Project Infrastructure Main Grails resources Additional Spring configuration Additional Hibernate mapping Web resources e.g. CSS, JavaScript etc. Java sources Jar archive libraries

2006 JavaOne SM Conference | Session BOF-2521 | 9 Command Line Targets ● Apache Ant bundled with Grails ● Many useful targets available: ● create-* (for creating Grails artifacts) ● generate-controller ● generate-views ● run-app ● test-app ● run-webtest Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 10 The Data Source // data source located in grails-app/conf Class ApplicationDataSource pooled = dbCreate = url = driverClassName = username = password = “sa” } Whether connection Pooling is enabled DB Auto creation with hbm2ddl Remaining connection settings

2006 JavaOne SM Conference | Session BOF-2521 | 11 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 12 The Application Domain ● Domain classes hold state and implement behaviour ● They are linked together via relationships (e.g. one-to-many) ● In Java domain classes have traditionally been handled by Object-Relational Mapping (ORM) ● Grails provides simple ORM built on Hibernate Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 13 Grails ORM (GORM) ● Extremely simple. No special class to extend or file to configure! class ExpenseReport Long Long relatesToMany = Set Date String employeeName } Each domain class has an ‘id’ and ‘version’ Defines one-to-many relationship to ExpenseItem

2006 JavaOne SM Conference | Session BOF-2521 | 14 Grails ORM (GORM) ● We’ve got this far, so lets define the other side! class ExpenseItem Long Long belongsTo = String Currency Integer amount } Defines the owning side of the relationship Each property maps To a column

2006 JavaOne SM Conference | Session BOF-2521 | 15 Grails Constraints ● Validation constraints can be defined using the ‘constraints’ property class ExpenseItem { constraints = { type(inList:['travel', 'accomodation']) amount(range:1..999) } Each node relates to a property Ensures the ‘type’ property Is one of the values in the list ‘amount’ must be in a range greater than 0 but less than 1000

2006 JavaOne SM Conference | Session BOF-2521 | 16 Dynamic Methods & Properties ● Grails injects methods and properties into domain classes at runtime: def r = ExpenseReport.findByEmployeeName('fred') def r = ExpenseReport.findBySubmissionDateGreaterThan(lastMonth) def reports = ExpenseReport.findAll() assert ! (new ExpenseItem().validate()) def er = new ExpenseReport(employeeName: 'Edgar').save()

2006 JavaOne SM Conference | Session BOF-2521 | 17 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 18 Controllers ● Controllers handle requests and prepare responses ● Response created by either delegating to a view or writing to the response ● A controller is a class containing closure properties that act on requests ● The convention used for the name of the controller and the actions within map to URIs. Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 19 The Controller ● The controller and action name map to the URI: /expenseReport/list class ExpenseReportController list = { [expenseReports : ExpenseReport.list()] } The name of the class is the first token in the URI Each action is a closure property An optional model is returned as a map

2006 JavaOne SM Conference | Session BOF-2521 | 20 Data Binding & Flow Control // save save = { def e = ExpenseItem.get(params.id) e.properties = params if(e.save()){ redirect(action:show,id:e.id) } else { render( view: 'create', model:[expenseItem:e] ) } Auto-type conversion from request parameters Dynamic get method Auto-type conversion To id type Example flow control via render and redirect methods

2006 JavaOne SM Conference | Session BOF-2521 | 21 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages (GSP) Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 22 Groovy Server Pages ● A view technology very similar to JSP, but with Groovy as the primary language ● More expressive and concise with support for embedded GStrings & Tags ● Layout support through integration with SiteMesh ● Ability to define dynamic tag libraries Source: Please add the source of your data here

2006 JavaOne SM Conference | Session BOF-2521 | 23 A GSP Example ● The GSP for the list action is named according to convention: grails-app/views/expenseItem/list.gsp ${it.type} – amount: ${it.amount} References the model returned by the controller Embedded GString expressions

2006 JavaOne SM Conference | Session BOF-2521 | 24 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 25 Dynamic Tag Libraries ● Easy definition of simple, logical and iterative tags: class ExpenseTagLib dateFormat = { attrs,body -> out << new SimpleDateFormat(attrs.format).format(attrs.date) } The name of the tag The body argument is a closure that can be invoked The attributes are passed as a map

2006 JavaOne SM Conference | Session BOF-2521 | 26 Dynamic Tag Libraries ● Using the tag requires no imports or configuration and can be reloaded at runtime!: Submitted: <g:dateFormat date="${report.submissionDate}" format="DD-MM-YYYY" /> <input type="hidden" name="submissionDate" value="${dateFormat( date:report.submissionDate, format:'DD-MM-YYYY')}" /> Tag called by name with the “g:” prefix Tag can also be called as a regular method!

2006 JavaOne SM Conference | Session BOF-2521 | 27 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages Tag Libraries Ajax Support Scaffolding Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 28 AJAX Support ● Built in “adaptive” tag library for Ajax ● Supports Prototype, Rico, and Yahoo (Dojo coming soon) ● Tags for remote linking, asynchronous form submission etc. ● Dynamic “render” method available for rendering XML snippets, or partial templates ● Save/Reload and dynamic tag libraries make Ajax even easier

2006 JavaOne SM Conference | Session BOF-2521 | 29 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages Tag Libraries Scaffolding Ajax Support Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 30 DEMO Scaffolding

2006 JavaOne SM Conference | Session BOF-2521 | 31 Agenda Groovy & Grails Getting Started The Application Domain Controllers Groovy Servers Pages Tag Libraries Scaffolding Ajax Support Java Integration

2006 JavaOne SM Conference | Session BOF-2521 | 32 Java Integration ● Now for the important bit, with Groovy and Grails you can: ● Call any existing Java library seamlessly ● Deploy as a WAR onto any JEE application server ● Write your domain model in Java, mapped with Hibernate, and still use dynamic methods! ● Take advantage of Hibernate’s power by mapping onto legacy systems. ● Use Spring’s dependency injection to integrate Controllers with existing services

2006 JavaOne SM Conference | Session BOF-2521 | 33 DEMO ECLIPSE INTEGRATION

2006 JavaOne SM Conference | Session BOF-2521 | 34 Summary ● With the advent on Web 2.0 agility is key ● Dynamic frameworks (Grails, Rails, Django etc.) provide this through quick iterative development with a clear productivity gain ● However, for large scale applications static- typing and IDE support is crucial ● Grails provides the ability to use a blended approach ● And most importantly it runs on the JVM!

2006 JavaOne SM Conference | Session BOF-2521 | 35 For More Information ● Groovy website – ● Grails website – ● Mailing lists – ● Graeme’s Blog – ● Upcoming books ‘The Definitive Guide to Grails’ by Apress and ‘Groovy in Action’ by Manning

2006 JavaOne SM Conference | Session BOF-2521 | 36 Q&A