Practical Grails

Practical Grails

Denver Open Source User's GroupApril 2009

Scott RyanSoaring Eagle [email protected]

Agenda

• Grails Overview• Grails Architecture• Domain Layer• Controller Layer• Service Layer• Presentation Layer• Build, Develop and Deploy• Security• Plugins

Overview

• Groovy Based

• Convention over configuration

• Don’t Repeat Yourself (DRY)

• Lots of code generation and scaffolding

• Leverages Leading Java Frameworks– Spring, Hibernate, Quartz, JSP, Ajax, Sitemesh,...

Overview• Wide IDE Support

– Intellij, Netbeans, Eclipse, ....

• Wide Server Support– Jetty, Tomcat, Websphere, Weblogic, Glassfish, Geronimo

• Very Dynamic development Environment• Two Current Versions

– 1.0.4 (Groovy 1.5) and 1.1 (Groovy 1.6)

• Huge Productivity Benefits• Leverages Java and JVM (Scalable)

Demo

• Trading system

Architecture

• Domain Layer– Gorm

• Controller Layer• Service Layer• Presentation Layer• Configuration Layer• Environment and Build layer• Plugin Layer

Domain Sample Code

• Sample Domain Code– Column Definition– Relationships (one to one, many to many, etc.)

• BelongsTo

– Constraints– Custom Hibernate Definitions

• Indexes (Simple or Complex), Blobs– Base Domain Class

Reference Data Handling

• Table Based– One or many

• String Based• Enum Based

– 1.0.4 Stores Ordinal• Temporary trick

– 1.1 Can store String• Plugins

Domain Environment Setup

• Based on environment– Runtime or Build controlled

• Sample Configuration File• Sample Bootstrap File

Transactions

• Uses Open Session in View– Modify data with care (discard)

• Spring Controlled Transactions• Can open transactions manually• Complex Transactions best done in Service

layer• Batch inserts are problematic but easily

addressed

Queries

• Dynamic Generated GORM Queries– Simple and compound

• Criteria Framework– Sorting

• Hand Coded SQL– Hibernate Based– Custom SQL

Criteria Query

// returns first 10 users who have an active

// account that has been created in the last

// 30 days and that have Grails-like

// bookmarks created in the last 7 days

def now = new Date()

def users = Bookmark.withCriteria {

comments {

like("text","%Grails%")

between("dateCreated", now-7, now)

}

between("dateCreated",now-30, now)

maxResults(10)

Controllers

• Should be light weight• Push business logic to the service layer• Remember security as REST is king• Download and upload is supported• Graphics and Reporting

Service Layer

• Reusable business logic• Complex transactions• Can be injected anywhere

– Domain, Controller, View• Spring Beans

Presentation Layer

• Layouts• Templates• Tags• Link Building• Images and CSS• Custom Taglibs

Ajax

• Built in with prototype• Can use other frameworks• Best practices to use shared templates

Build and Configuration

• Multiple Environments– 3 defaults

• Gant Based and Maven (1.1)• BIG War's but can make them smaller with

some work• Lots of targets

Security

• Use a framework to start• Remember this is a REST Application• Leverage Custom filters• Encrypt what you need to

Plugins

• Framework for adding functionality• Can be used to optimize applications• Can be used to add functionality to base

framework• Easy to install

– 1.1 improves the architecture• Hard to tell what is useful and supported

Favorite Plugins

• Spring Security• Quartz• Grails UI and Charting• Mail• Settings• Help Balloons• mor.ph• Testing (Included in 1.1)

Questions

• Contact Me– Scott Ryan– [email protected]– www.soaringeagleco.com