Java Tech & Tools | Grails in the Java Enterprise | Peter Ledbrook
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This document discusses how to integrate Grails applications with various enterprise systems and processes. It covers integrating Grails with build tools like Ant and Maven, managing dependencies, connecting to legacy databases, deploying applications, and integrating with Spring frameworks for messaging, web services, and other enterprise features. Grails can work with many external systems through plugins, custom ORM mappings, and by treating Grails as a Spring application. This allows Grails applications to fit into a variety of enterprise environments and development processes.
![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
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![Example
import ...
beans = {
credentialMatcher(Sha1CredentialsMatcher) {
storedCredentialsHexEncoded = true
}
sessionFactory(ConfigurableLocalSessionFactoryBean) {
dataSource = ref("dataSource")
hibernateProperties = [
"hibernate.hbm2ddl.auto": "create-drop",
"hibernate.show_sql": true ]
}
}
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![JMS Plugin Example
Listen for messages
class ListeningService {
static expose = ['jms']
def onMessage(message) {
assert message == 1
}
}
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Java Tech & Tools | Grails in the Java Enterprise | Peter Ledbrook
- 1. Peter Ledbrook / VMware Grails in the Java Enterprise Tuesday, 1 November 11
- 2. 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) 2 Tuesday, 1 November 11
- 3. What is Grails? Grails Servlet Web MVC GSP (Views) Container GORM Database I18n (Data Access) Build Test Support Doc Engine 3 Tuesday, 1 November 11
- 4. What is Grails? Grails 4 Tuesday, 1 November 11
- 5. 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 5 Tuesday, 1 November 11
- 6. Say bye-bye to the plumbing! 6 Tuesday, 1 November 11
- 7. Demo Demo 7 Tuesday, 1 November 11
- 8. Enterprise requirements Web App Messaging JEE Legacy Services Databases Is this a problem for Grails apps? 8 Tuesday, 1 November 11
- 9. Integration Points Build Dependencies Database Deployment Spring 9 Tuesday, 1 November 11
- 10. Integration Points Build Dependencies Database Deployment Spring 10 Tuesday, 1 November 11
- 11. Build 11 Tuesday, 1 November 11
- 12. 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 12 Tuesday, 1 November 11
- 13. 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 13 Tuesday, 1 November 11
- 14. 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 14 Tuesday, 1 November 11
- 15. Getting Started mvn archetype-generate ... e.g. -Xmx256m mvn initialize -XX:MaxPermSize=256m Set MAVEN_OPTS Optional: add ‘pom true’ to dependency DSL 15 Tuesday, 1 November 11
- 16. Packaging Types ‘war’ • Must configure execution section • Works with plugins that depend on ‘war’ ‘grails-app’ • Less configuration ‘grails-plugin’ • For plugins! 16 Tuesday, 1 November 11
- 17. Maven & Grails Plugins > grails release-plugin == > mvn deploy 17 Tuesday, 1 November 11
- 18. 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’ 18 Tuesday, 1 November 11
- 19. Maven & Grails Plugins Or: grails.project.dependency.resolution = { ... plugins { compile ":hibernate:1.3.6" } ... } 19 Tuesday, 1 November 11
- 20. 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 20 Tuesday, 1 November 11
- 21. What the future holds... Grails 3.0 will probably move to Gradle • More powerful and more flexible • Standard, well documented API • Ant & Maven support 21 Tuesday, 1 November 11
- 22. Integration Points Build Dependencies Database Deployment Spring 22 Tuesday, 1 November 11
- 23. Dependencies are JARs Use any Java library you like! Full support for Maven-compatible repositories Declarative dependencies Plugins can be declared the same way 23 Tuesday, 1 November 11
- 24. Dependency DSL grails.project.dependency.resolution = { inherits "global" log "warn" repositories { grailsHome() mavenCentral() mavenRepo "http://localhost:8081/..." } ... } 24 Tuesday, 1 November 11
- 25. 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" } ... } 25 Tuesday, 1 November 11
- 26. Integration Points Build Dependencies Database Deployment Spring 26 Tuesday, 1 November 11
- 27. ‘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 27 Tuesday, 1 November 11
- 28. 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" } } 28 Tuesday, 1 November 11
- 29. 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 29 Tuesday, 1 November 11
- 30. 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 30 Tuesday, 1 November 11
- 31. Constraints Given domain class: org.example.myapp.domain.Book Then: src/java/org/example/myapp/domain/BookConstraints.groovy constraints = { title blank: false, unique: true ... } 31 Tuesday, 1 November 11
- 32. 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 32 Tuesday, 1 November 11
- 33. 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 ... 33 Tuesday, 1 November 11
- 34. Share your model! 34 Tuesday, 1 November 11
- 35. Database Management Hibernate ‘update’ + Production data = ? 35 Tuesday, 1 November 11
- 36. Database Migration Plugin Pre-production, Hibernate ‘update’ or ‘create-drop’ dbm-generate-changelog dbm-changelog-sync Change domain model dbm-gorm-diff dbm-update 36 Tuesday, 1 November 11
- 37. Reverse Engineering Plugin class Person { String name Integer age ... } 37 Tuesday, 1 November 11
- 38. Database Management Database Migration http://grails.org/plugin/database-migration Reverse Engineering http://grails.org/plugin/database-migration 38 Tuesday, 1 November 11
- 39. Integration Points Build Dependencies Database Deployment Spring 39 Tuesday, 1 November 11
- 40. grails war Build properties: • grails.war.copyToWebApp • grails.war.dependencies • grails.war.resources • grails.project.war.file 40 Tuesday, 1 November 11
- 41. 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 41 Tuesday, 1 November 11
- 42. Data Source JNDI: dataSource { jndiName = "java:comp/env/myDataSource" } System property: dataSource { url = System.getProperty("JDBC_STRING") } 42 Tuesday, 1 November 11
- 43. 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 43 Tuesday, 1 November 11
- 44. Integration Points Build Dependencies Database Deployment Spring 44 Tuesday, 1 November 11
- 45. 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 45 Tuesday, 1 November 11
- 46. Example import ... beans = { credentialMatcher(Sha1CredentialsMatcher) { storedCredentialsHexEncoded = true } sessionFactory(ConfigurableLocalSessionFactoryBean) { dataSource = ref("dataSource") hibernateProperties = [ "hibernate.hbm2ddl.auto": "create-drop", "hibernate.show_sql": true ] } } 46 Tuesday, 1 November 11
- 47. Enterprise Integration Spring opens up a world of possibilities • Spring Integration/Camel • Messaging (JMS/AMQP) • ESB • RMI, HttpInvoker, etc. Web services & REST 47 Tuesday, 1 November 11
- 48. Grails Plugins Routing JMS, RabbitMQ CXF, Spring-WS, WS-Client REST 48 Tuesday, 1 November 11
- 49. 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' } 49 Tuesday, 1 November 11
- 50. 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 } } } 50 Tuesday, 1 November 11
- 51. JMS Plugin Example Listen for messages class ListeningService { static expose = ['jms'] def onMessage(message) { assert message == 1 } } 51 Tuesday, 1 November 11
- 52. Demo Demo 52 Tuesday, 1 November 11
- 53. 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 53 Tuesday, 1 November 11
- 54. More info w: http://grails.org/ f: http://grails.org/Mailing+Lists e: [email protected] t: pledbrook b: http://blog.springsource.com/author/peter-ledbrook/ 54 Tuesday, 1 November 11
- 55. Q&A Q&A 55 Tuesday, 1 November 11