Java Tech & Tools | Grails in the Java Enterprise | Peter Ledbrook

Peter Ledbrook / VMware Grails in the Java EnterpriseTuesday, 1 November 11

What is Grails? Rapid Web Application Development Framework • for the JVM • with first-class Java integration Inspired by Ruby on Rails, Django and others • Convention over Configuration • Don’t Repeat Yourself (DRY) 2Tuesday, 1 November 11

What is Grails? Grails Servlet Web MVC GSP (Views) Container GORM Database I18n (Data Access) Build Test Support Doc Engine 3Tuesday, 1 November 11

What is Grails? Grails 4Tuesday, 1 November 11

What is Grails? Web Controllers The Domain Model i18n bundles Business Logic Custom View Tags Views & Layouts Libraries (JARs) Build Commands Additional Sources Tests Web Resources 5Tuesday, 1 November 11

Say bye-bye to the plumbing! 6Tuesday, 1 November 11

Demo Demo 7Tuesday, 1 November 11

Enterprise requirements Web App Messaging JEE Legacy Services Databases Is this a problem for Grails apps? 8Tuesday, 1 November 11

Integration Points Build Dependencies Database Deployment Spring 9Tuesday, 1 November 11

Build 11Tuesday, 1 November 11

Build Remember the Grails project structure? • add in build events and... Can’t build natively with other build tools! Ant Maven Gradle Grails Build System 12Tuesday, 1 November 11

Ant Integration An Ant task built in (grails.ant.GrailsTask) Template Ant build: grails integrate-with --ant • Uses Ivy for dependency management • Not compatible with Ant 1.8 ...or use ‘java’ task to call Grails command • Grails manages dependencies • Use ‘grails’ for build 13Tuesday, 1 November 11

Maven Maven Grails Plugin: https://github.com/grails/grails-maven Use Maven 2 or 3 to build Grails projects Declare dependencies in POM Works for both applications and plugins! Integration test framework: https://github.com/grails/ grails_maven_plugin_testing_tests 14Tuesday, 1 November 11

Getting Started mvn archetype-generate ... e.g. -Xmx256m mvn initialize -XX:MaxPermSize=256m Set MAVEN_OPTS Optional: add ‘pom true’ to dependency DSL 15Tuesday, 1 November 11

Packaging Types ‘war’ • Must configure execution section • Works with plugins that depend on ‘war’ ‘grails-app’ • Less configuration ‘grails-plugin’ • For plugins! 16Tuesday, 1 November 11

Maven & Grails Plugins > grails release-plugin == > mvn deploy 17Tuesday, 1 November 11

Maven & Grails Plugins Either: <dependency> <groupId>org.grails.plugins<groupId> <artifactId>hibernate</artifactId> <type>grails-plugin</type> </dependency> Use ‘mvn deploy’ or Release plugin! And ‘pom: false’ 18Tuesday, 1 November 11

Maven & Grails Plugins Or: grails.project.dependency.resolution = { ... plugins { compile ":hibernate:1.3.6" } ... } 19Tuesday, 1 November 11

Customise the Build Create new commands in <proj>/scripts Package the commands in a plugin! Create <proj>/scripts/_Events.groovy • Interact with standard build steps • Add test types • Configure embedded Tomcat 20Tuesday, 1 November 11

What the future holds... Grails 3.0 will probably move to Gradle • More powerful and more flexible • Standard, well documented API • Ant & Maven support 21Tuesday, 1 November 11

Dependencies are JARs Use any Java library you like! Full support for Maven-compatible repositories Declarative dependencies Plugins can be declared the same way 23Tuesday, 1 November 11

Dependency DSL grails.project.dependency.resolution = { inherits "global" log "warn" repositories { grailsHome() mavenCentral() mavenRepo "http://localhost:8081/..." } ... } 24Tuesday, 1 November 11

Dependency DSL grails.project.dependency.resolution = { inherits "global" log "warn" ... dependencies { compile "org.tmatesoft.svnkit:svnkit:1.3.3" test "org.gmock:gmock:0.8.1" } ... } 25Tuesday, 1 November 11

‘Legacy’ Databases Grails can create a database from your domain model... ...but what if you don’t own the database? • DBA determines structure • Company conventions • Existing ‘legacy’ database 27Tuesday, 1 November 11

Option 1: Custom ORM mapping No existing domain model Schema not too far off the beaten track class Book { ... static mapping = { table "books" title type: "books" author column: "author_ref" } } 28Tuesday, 1 November 11

Option 2: JPA annotations Existing Java/JPA domain model <?xml version=1.0 encoding=UTF-8?> <!DOCTYPE ...> <hibernate-configuration> <session-factory> <mapping class="org.ex.Book"/> <mapping class="org.ex.Author"/> ... </session-factory> </hibernate-configuration> grails-app/conf/hibernate/hibernate.cfg.xml 29Tuesday, 1 November 11

Option 3: Hibernate XML Mappings You have Java model + Hibernate mapping files Schema is way off the beaten track <?xml version=1.0 encoding=UTF-8?> <!DOCTYPE ...> <hibernate-configuration> <session-factory> <mapping resource="org.ex.Book.hbm.xml"/> <mapping resource="org.ex.Author.hbm.xml"/> ... </session-factory> </hibernate-configuration> grails-app/conf/hibernate/hibernate.cfg.xml 30Tuesday, 1 November 11

Constraints Given domain class: org.example.myapp.domain.Book Then: src/java/org/example/myapp/domain/BookConstraints.groovy constraints = { title blank: false, unique: true ... } 31Tuesday, 1 November 11

Option 4: GORM JPA Plugin GORM layer over JPA Use your own JPA provider Useful for cloud services that only work with JPA, not Hibernate 32Tuesday, 1 November 11

Option 5: Remote service back-end Don’t have to use GORM Use only controllers and services • Grails services back onto remote services Web App SOAP, RMI, HTTP Invoker, etc. Invoice Log Service ... 33Tuesday, 1 November 11

Share your model! 34Tuesday, 1 November 11

Database Management Hibernate ‘update’ + Production data = ? 35Tuesday, 1 November 11

Database Migration Plugin Pre-production, Hibernate ‘update’ or ‘create-drop’ dbm-generate-changelog dbm-changelog-sync Change domain model dbm-gorm-diff dbm-update 36Tuesday, 1 November 11

Reverse Engineering Plugin class Person { String name Integer age ... } 37Tuesday, 1 November 11

Database Management Database Migration http://grails.org/plugin/database-migration Reverse Engineering http://grails.org/plugin/database-migration 38Tuesday, 1 November 11

grails war Build properties: • grails.war.copyToWebApp • grails.war.dependencies • grails.war.resources • grails.project.war.file 40Tuesday, 1 November 11

Control of JARs grails.project.dependency.resolution = { defaultDependenciesProvided true inherits "global" log "warn" ... } grails war --nojars => WEB-INF/lib/<empty> => No Grails JARs in WEB-INF/lib 41Tuesday, 1 November 11

Data Source JNDI: dataSource { jndiName = "java:comp/env/myDataSource" } System property: dataSource { url = System.getProperty("JDBC_STRING") } 42Tuesday, 1 November 11

Data Source Config.groovy: grails.config.locations = [ "file:./${appName}-config.groovy", "classpath:${appName}-config.groovy" ] For run-app: ./<app>-config.groovy For Tomcat: tomcat/lib/<app>-config.groovy 43Tuesday, 1 November 11

Grails is Spring Spring MVC under the hood Grails provides many useful beans • e.g. grailsApplication Define your own beans! • resources.xml/groovy • In a plugin 45Tuesday, 1 November 11

Example import ... beans = { credentialMatcher(Sha1CredentialsMatcher) { storedCredentialsHexEncoded = true } sessionFactory(ConfigurableLocalSessionFactoryBean) { dataSource = ref("dataSource") hibernateProperties = [ "hibernate.hbm2ddl.auto": "create-drop", "hibernate.show_sql": true ] } } 46Tuesday, 1 November 11

Enterprise Integration Spring opens up a world of possibilities • Spring Integration/Camel • Messaging (JMS/AMQP) • ESB • RMI, HttpInvoker, etc. Web services & REST 47Tuesday, 1 November 11

Grails Plugins Routing JMS, RabbitMQ CXF, Spring-WS, WS-Client REST 48Tuesday, 1 November 11

JMS Plugin Example Add any required dependencies (BuildConfig.groovy) dependencies { compile org.apache.activemq:activemq-core:5.3.0 } Configure JMS factory (resources.groovy) jmsConnectionFactory(org.apache.activemq.ActiveMQConnectionFactory) { brokerURL = vm://localhost } 49Tuesday, 1 November 11

JMS Plugin Example Send messages import javax.jms.Message class SomeController { def jmsService def someAction = { jmsService.send(service: initial, 1) { Message msg -> msg.JMSReplyTo = createDestination(service: reply) msg } } } 50Tuesday, 1 November 11

JMS Plugin Example Listen for messages class ListeningService { static expose = [jms] def onMessage(message) { assert message == 1 } } 51Tuesday, 1 November 11

Demo Demo 52Tuesday, 1 November 11

Summary Various options for integrating Grails with: • Development/build • Deployment processes Works with many external systems • Solid support for non-Grailsy DB schemas • Flexible messaging & web service support 53Tuesday, 1 November 11

More info w: http://grails.org/ f: http://grails.org/Mailing+Lists e: pledbrook@vmware.com t: pledbrook b: http://blog.springsource.com/author/peter-ledbrook/ 54Tuesday, 1 November 11

Q&A Q&A 55Tuesday, 1 November 11

Java Tech & Tools | Grails in the Java Enterprise | Peter Ledbrook

by JAX London on Nov 08, 2011

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Java Tech & Tools | Grails in the Java Enterprise | Peter Ledbrook Presentation Transcript