This document discusses various ways to integrate Grails applications into enterprise environments and processes. It covers integration points such as build systems, dependency management, databases, deployment, and the Spring framework. Specific topics include using Maven or Ant for builds, handling legacy databases through custom ORM mappings or XML files, configuring data sources and dependencies, and leveraging Spring and plugins for enterprise features like messaging and web services. Overall, the document outlines Grails' flexibility in working with external systems and processes commonly found in enterprise applications.

1. Grails in the Enterprise
Peter Ledbrook
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2. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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3. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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4. Build
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5. 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
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6. 6
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7. Maven
• Maven Grails Plugin:
https://github.com/grails/grails-maven
• Use Maven 2 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
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8. Getting Started
mvn archetype-generate ...
mvn initialize -Xmx256m
e.g.
-XX:MaxPermSize=256m
Set MAVEN_OPTS
Optional: add ‘pom true’ to dependency DSL
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9. Packaging Types
• ‘war’
– Must configure execution section
– Works with plugins that depend on ‘war’
• ‘grails-app’
– Less configuration
• ‘grails-plugin’
– For plugins!
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10. 10
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11. Maven & Grails Plugins
> grails release-plugin
==
> mvn deploy
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12. 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’
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13. Maven & Grails Plugins
Or:
grails.project.dependency.resolution = {
...
plugins {
compile ":hibernate:1.3.6"
}
...
}
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14. 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
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15. What the future holds...
• Grails 2.0 will move to Gradle
– More powerful and more flexible
– Standard, well documented API
– Ant & Maven support
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16. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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17. Dependency DSL
grails.project.dependency.resolution = {
inherits "global"
log "warn"
repositories {
grailsHome()
mavenCentral()
mavenRepo "http://localhost:8081/..."
}
...
}
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18. 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"
}
...
}
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19. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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20. ‘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
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21. Option 1: Custom ORM mapping
class Book {
...
static mapping = {
table "books"
title type: "books"
author column: "author_ref"
}
}
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22. Option 2: JPA annotations
<?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>
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23. Option 3: Hibernate XML Mappings
<?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>
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24. Constraints
Given domain class:
org.example.myapp.domain.Book
Then:
src/java/org/example/myapp/domain/BookConstraints.groovy
constraints = {
title blank: false, unique: true
...
}
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25. 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
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26. Share your model!
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27. Database Management
• Hibernate auto-DDL
– Good for dev & test
– Bad for production!
• Data migration
– http://grails.org/plugin/database-migration
• Reverse engineer a model
– http://grails.org/plugin/db-reverse-engineer
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28. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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29. grails war
• Build properties:
– grails.war.copyToWebApp
– grails.war.dependencies
– grails.war.resources
– grails.project.war.file
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30. 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
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31. Data Source
JNDI:
dataSource {
jndiName = "java:comp/env/myDataSource"
}
System property:
dataSource {
url = System.getProperty("JDBC_STRING")
}
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32. 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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33. Integration Points
• Build
• Dependencies
• Database
• Deployment
• Spring
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34. 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
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35. 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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36. Enterprise Integration
• Spring opens up a world of possibilities
– Spring Integration/Camel
– Messaging (JMS/AMQP)
– ESB
– RMI, HttpInvoker, etc.
• Web services & REST
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37. Grails Plugins
• Routing
• JMS, RabbitMQ
• CXF, Spring-WS, WS-Client
• REST
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38. 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
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39. Thank you!
Q&A
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