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Grails in the Enterprise 2010L.A. JUG April 4th 2010By Todd R. Ellermann
With Key Contributions from VT team members: • Ken Ellinwood, David Benjamin, Ari Miller
Todd R. Ellermann
B.S. Computer Engineering University of Arizona MBA Arizona State University (Certificate in
Software Engineering Management) V.P. of Engineering for VirtualTourist.com Java Certified 1998 http://www.betterwebapp.com
Wrote the same web application in 8 languages (screencast, source code, measured silly things like screen cast time and lines of code etc…)
toddecus (aim, twitter, yahoo, skype etc…) todd@virtualtourist.com
VirtualTourist.com
Expedia>TripAdvisor>VirtualTourist Online Travel Community with emphasis
on Real people writing reviews of Hotels and talking about things to do.
Monetize through advertising (CPM,CPC) VirtualTourist.com Stats:
8.4 Million Visitors 30 Million PV / Month 1.2 Million Members 1.7 Million Travel Tips 3.7 Million Photos 10 Year anniversary this year!
What we are going to cover
Why we chose Groovy/Grails
Quick “what is grails” Grails Versions Ecosystem around Grails
Plug-ins IDE/Tools Building Grails Apps
Convention/Configuration Under The Hood
Spring Hibernate Sitemesh
Use of Dynamic Language Subclass vs. Closure
GORM Multiple-data sources GSQL URL Mapping Grails Console Testing Hot Deployment Normal Java stuff still
works Deployment Environment JMX et al… Web Services VT Today
VT June 2008
PHP Batch
Intro to Groovy / Grails
Groovy ( 1.7.1 latest) Dynamic Scripting Language Runs on JVM Java Syntax - Semi-colons + Closures +
heredoc http://groovy.codehaus.com
Grails (1.2.2, or 1.3-RC1) Code By convention Framework Best in Breed Java under the hood DRY (Don’t Repeat Yourself) http://www.grails.org (SpringSource)
Do DEMO HERE
Create App Generate GORM objects Generate controllers
Def scaffold = true Generate all
Run-app show validate(), errors etc.. Passing from a map to a
domain.properties
Grails Versions
Grails 1.0 (February 4, 2008) (1.0.5 latest) Rough but stable (1.0.3 very different than 1.0.4-5) 1.0.4 probably should have been full release Intro of GORM DSL over hibernate
Grails 1.1 (March 10,2009) (1.1.2 latest) What we are on today (1.1.1) + Groovy 1.5.7 Performance improvements (GSP optimization) Testing ENUM Maven Log4j DSL
Grails 1.2 (Dec 23rd, 2009) (1.2.2 latest) HOT!!! Dependency Resolution (ivy) Named Queries Performance Improvement (io push+precompile) 2-
3x faster SPRING 3.0 + Spring Annotation Detailed Datasources Switch to Tomcat as default container (Spring
source influence) No technical reason provided other than springsource
knows tomcat better Run exact Test not all tests (improved developer
cycle)
Grails 1.3-RC1 ???? Uhhh…OK
Move to Groovy 1.7
More maven crap
Grails 2.0 ???? Not sure why I care
OSGi Plugins
dependency declaration
Security abstraction
Plug-in Ecosystem List
388 plug-ins up from 35 two years ago
Jetty/Tomcat Quartz AppEngine GrailsUI Searchable Acegi Shiro/Nimble (jSecurity) Weceem (cms) Datasources Hibernate Search
Simple commands:grails uninstall-plugin tomcatgrails install-plugin jetty
P6spy GSolr Jquery/YUI Paypal Xfire Multi-Tenant (web
hosting) Jndi Ldap Spring MVC, cache, WS Flex Gorm
VERY Easy to write we have a few internal VT plug-ins
Plug-in Ecosystem Problems
Abandoned plug-ins Compatability of two different plugins:
Multi-tenant collides with anything that gets into hibernate interception
Plug-in dependency/assumptions not clear:
Weceem imports Acegi Nimble assumes shiro, spock, compass et al…
What Version of Grails does this plug-in work with? (Getting better)
Tools IDE
IntelliJ V 8 was a little rough still V9 is useable, still a little rough in areas
VI Emacs Eclipse is WAY behind Netbeans is OK (from what I hear) Groovysh GrailsConsole
Maven/Gradle/Grapes/GANT Grapes is groovy grab() method (ibiblio etc..)
GANT is DSL on top of ANT (no more xml) Gradle is what Maven should have been (according to Gradle guys not me, verdict not in yet)
Not much tool support yet No XML Can call ANT, GANT or Maven pom goals etc..
Maven Grails Plugin (Maven 2.0.9 and above) Tool support .m2/settings.xml
<pluginGroups> <pluginGroup>org.grails</pluginGroup> </pluginGroups> Create Grails project
Grails built on Hudson with Maven Gradle (recent change)
import com.jidesoft.swing.JideSplitButton@Grab(group='com.jidesoft', module='jide-oss', version='[2.2.1,2.3.0)')public class TestClassAnnotation { public static String testMethod () { return JideSplitButton.class.name }}
mvn org.apache.maven.plugins:maven-archetype-plugin:2.0-alpha-4:generate \ -DarchetypeGroupId=org.grails \ -DarchetypeArtifactId=grails-maven-archetype \ -DarchetypeVersion=1.2.0 \ -DgroupId=example -DartifactId=my-appMvn initializeExample is from here: http://www.grails.org/Maven+Integration
Convention over configuration
Directories mean something.grails-app/conf : data sources, spring, url mapping, configs,Bootstrapgrails-app/domain : map these to the databasegrails-app/controllers : abstraction above servlet, Command Objectsgrails-app/views : GSP’s and Templatesgrails-app/taglib : custom taglib’sgrails-app/services : Singleton by default Tx or NoTx
Names mean something. FooService.groovy FooFilters.groovy FooTagLib.groovy FooController.groovy FooCommand.groovy also @Validateable
Under The Hood: Spring
/conf/resources.groovy (Spring DSL)
import org.springframework.context.*
class FooController implements ApplicationContextAware { ApplicationContext applicationContext CacheService getCacheService() { applicationContext.getBean(“cacheService”)}}
beans = { switch(GrailsUtil.environment) {
case "test": serviceLocator( com.vtourist.hotel_tool.testing.ServiceLocator4Tests) {} locationService( com.vtourist.service.location.client.MockLocationService) {}
break default: serviceLocator(com.vtourist.common.service.DefaultServiceLocator) {
jndiName = DefaultServiceLocator.DEFAULT_JNDI_NAME } locationService(com.vtourist.service.location.client.LocationServiceImpl, ref('serviceLocator'))
{} break }
locationDetailsCache( com.vtourist.service.location.client.LocationDetailsMRUCache, 1000) { locationService = ref('locationService')
} }
• Application Context Aware
15
Grails 1.2 More Spring
From Grails Release Notes: http://www.grails.org/1.2+Release+Notes
In this example, going to /hello.dispatch will execute the handleRequest() method and atempt to render either a GSP or JSP view at grails-app/views/hello.(jsp|gsp)
Under The Hood: Hibernate
location.hbm.xml override autowire domain object mapping
Dynamic Finders: def loc = Location.findByName(“El Segundo”)
There are also “by example”: def loc = Location.find( new Location(name:’San Juan’)
)
Using GORM DSL to create Criteria Query
17
Hibernate Continued
SQL Get to use Caches and automap to domain objects
Note: Use of “heredoc” style GString. Really useful with SQL and inline Templates (emails et al…)
18
Actual SQL executed
Hibernate: SELECT L.ID as ID32_0_, L.cities as cities32_0_, L.latitude as latitude32_0_, L.level as level32_0_, L.longitude as longitude32_0_, L.name as name32_0_, L.NextLevel as NextLevel32_0_, L.Parent1 as Parent8_32_0_, L.Parent2 as Parent9_32_0_, L.parent3 as parent10_32_0_, L.parent4 as parent11_32_0_, LM.Location as Location23_1_, LM.Cities as Cities23_1_, LM.HotelPics as HotelPics23_1_, LM.HotelTips as HotelTips23_1_, LM.Members as Members23_1_, LM.Pictures as Pictures23_1_, LM.Tips as Tips23_1_ FROM Location L, LocationMeta LM WHERE ID32_0_ = Location23_1_ AND Tips23_1_ >= ?Bangkok has 10656 tips
Under The Hood: Sitemesh GSP == JSP + JSTL + Grails Taglib + Groovy Taglibs are Sooo Easy
Templates sitemesh _rightWellGoogleTextLinks.gsp <g:render template=”rightWellGoogleTextLinks"
model="[’textLinksResult':textLinksResult]" />
class VirtualTouristTagLib { static namespace = ‘vt’ def locationService def locationForLocationName = { attrs, body ->
def locationName = attrs[’locationName'] def location = locationService.getLocationByName(locationName)if(location != null) { request.setAttribute(’location', location) out << body() }
}}
<vt:locationForLocationName locationName=“$[locationName]”> <h1>This city ${locationName}‘s parent location is ${location.parent.name}</h1></vt:locationForLocationName>
Dynamic Method Invocation
• Groovy allows method names to be specified in Strings – e.g., instance.”foo”() calls the instance’s foo() method.
• Can be used to simplify method dispatch.
Closures vs Subclasses
Template Method pattern revisited from GOF
abstract class BaseAlgorithm { protected int value1, value2;
public abstract int calculate();}
class SubAlgorithm extends BaseAlgorithm {{ public int caculate() { return value1 + value2; }}
1.2.3.4.5.6. 7.8.9.10.11.12.13.14.15.16.17.18.19.20.
class Algorithm { int value1, value2
int calculate( def closure) { return closure( this) }}
a = new Algorithm( value1: 40, value2: 2)
println a.calculate( { algs -> algs.value1 - algs.value2 })
Java Version
Groovy Version
GORM Datasource DSL
• Bind all domain objects to this datasource depending on environment.
• Access to hibernate directly• Cache Control• GORM will “create” tables
automatically in test,console but “validate” in other ENV’s
• Can use JNDI in Integration, QA, and Production
Datasources Plug-in
DatasourcesHow do I bind GORM objects to 2 or more datasources?
Note the binding of domain objects to different domain.Not shown. The damn tables have to also exist in our original VT schema!
Note the lack of bound domains for 3rd datasource, now we can use that for “GSQL”
Be careful with GSQL et al… not the same rules for releasing connections back to the pool.
Future: How do I have some objects bound Read/Write and some bound Read Only to a slave?
GSQL/JDBC
Be careful there are differences between getting your Sql object from jndi/ datasources vs instantiating connection live.
Grails Console
Demo Console Quick turn around to answer the
question what happens when/if?
26
Grails Controller -- Command
DTO, Details Object, or Grails Command
Unit Testing That Controller
HotDeploy
Everything not “injected” Domain out Command out
Controllers, GSP’s, Views, some services
Groovy = Java – Junk + Killer Ecosystem
Everything you can do in Java I can do better/faster or at least the same:
Logging (log4j) Quartz Annotations JNDI SpringSecurity (ACEGI) JMS Xstream JDBC Continue to abuse the J2EE label etc…
WAR on the JVM
grails [env=production] war Compiles source to byte code Includes groovyAll.jar Includes 53 other jars (grails, spring
hibernate,etc..) Precompiles gsp Creates fooApp.war with environment
settings of “production” Everyone with existing “J2EE” infrastructures is
going to love this. It’s like the linux server in the closet.
“So I skipped the EJB’s and finished a year early… does mgmt really care… No!” -- unknown
“Services”
The defaults of Grails convention-over-configuration encourage a service layer within the application
Service classes are Spring singletons(configurable) dependencies are injected by Spring IOC dependencies include other services and data access layer
"domain" objects Local clients easily access services
service singletons are injected by Spring IOC Controllers do the following to access a local service:
class AbcController { def xyzService // causes Spring to auto inject xyzService def doStuff = {
def arg1 = params.arg1….result = xyzService.businessMethod( arg1 )….
}
URL Mapping
URL DSL easy to create SEO friendly URLs or even map legacy URL’s to new controllers.
Also interestingly easy to take true RESTful approach
33
JMX example
Exposing a Grails Service to a remote client requires installing plug-ins for desired protocols
add the protocols to a static member list on your service class
class MonitorService { static expose = ['jmx'] def counter = 1 def incrementCounter() { ++counter } }
What if I could use this to tell the front end applications which service servers were currently available and prevent downtime as new code bases were deployed?
34
JMX Console
VT Today
What we covered
Why we chose grails
Grails Ecosystem and Versions
Spring Hibernate Use of Dynamic
Language
Developer cycle time GORM + GrailsConsole
Testing Java Me Too! Deployment
Resources
Sites http://www.grails.org/ http://groovy.codehaus.org/ Nabble (mailing list surfaced) IBM Mastering Grails et al…
Books The Difinitive Guide to Grails 2nd Edition Groovy In Action Beginning Groovy & Grails Novice -> Professional Its
OK not great
Mailing lists Grails About 80 messages a day Groovy
Sad attempt at Groovy Humor
class BestTravelWebsite { def domainName def parent def memberCount def photoCount def travelTipCount def UniqueVisitors def pageViews}
def virtualTourist = new BestTravelWebsite(domainName:”www.virtualtourist.com”,parent:tripAdvisor,memberCount:1,200,000,photoCount: 3,702,063,travelTipCount:1,781,378,uniqueVisitors: 8,400,000,pageViews: 32,000,000)
def expedia = new BestTravelWebsite(domainName: ”www.expedia.com et al….”, tickerSymbol: ”EXPE”)
def tripAdvisor = new BestTravelWebsite(domainName:”www.tripadvisor.com et al…”,parent:expedia)
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