Spring Northwest Usergroup Grails Presentation
- 2. What is Grails?Rapid development frameworkConvention over configurationBuilt on proven technologiesSpring IoCSpring MVCHibernateSitemeshUses groovy
- 3. What is Groovy?A scripting language which runs on the JVMGroovy Objects extend java.lang.ObjectSeamless Java integrationDesigned for the Java developerLinear learning curveFamiliar syntax
- 4. A Java Class
- 5. And A Groovy Example
- 6. What's The DifferenceNONE!Groovy lets you use Java code in your groovy classes / scriptsWe can make this groovier
- 7. A Groovy Example V2No constructor – groovy allows you to pass in a map to set variablesClosures (the each function)Null safe operations '?'Extends standard JDK classes objects (the each function)Typing optional – def keyword
- 8. GroovyAllows you to use Java + Static typing when necessaryAdds additional functionality to standard JDK classesClosuresMOP Meta Object ProtocolJava like syntaxLinear learning curve, you can start with Java and re-factor to make it groovier
- 9. GrailsUses best practices with the power of Groovy to make a rapid development environment built on proven technologies you already know
- 10. Grails ContProvides a view layer (GSP's + Sitemesh)Service layer (Service spring managed beans)Repository (GORM, Grails object relational mapping...hibernate abstraction)Unit / integration tests a key featureThe grails app structure
- 11. Grails PluginsProvide a full slice of the applicationViewsControllersDomain objectsSessionsScriptsAllow to make a application modular, great for teams working on feature sets and to reuse ability
- 12. DemoLets take a look at how easy it is to create a grails application and integrate spring librariesWe'll create a basic application to search twitter using the api, cache and display the results
- 13. Demo (contd)Create the application, type 'grails create-app twitter-search' from the command lineWe now have a fully functional web application, this can be run using 'grails run-app'
- 14. Demo (contd)Create a service bean to query twitter. 'grails create-service com.demo.TwitterService'
- 15. Demo (contd)Create a controller to query the service 'grails create-controller com.demo.TwitterSearch'Notes: 1) Spring injects the TwitterService class based on the variable name 2) Controller actions are defined as groovy closures. We returna map to the view. By convention the view will be under 'grails-app/views/${controller}/${action}‘ Iefor the above: 'grails-app/views/twitterSearch/search.gsp'
- 16. Demo (cont)Create the view 'grails-app/views/twitterSearch/seach.gsp'Note: the layout meta tag, this tells sitemesh to decorate the page using the 'grails-app/layouts/main.gsp' template
- 17. CompleteWe now have a basic web application displaying results from the twitter api
- 18. Demo (cont)Run 'grails-stats'18 lines of code !
- 19. Integrating with SpringWe've not interacted with Spring directly so farGrails has taken over in the background configuring the view resolver, url mappings / controllers for Spring MVN, injecting session beans
- 20. Spring In GrailsWe'll look at making further use of Spring in Grails by using Spring AOP to cache the search results
- 21. Spring AOP In Grails1) We place the required lib directoryaspectjrt.jar (v1.5+) aspectjweaver.jar (v1.5+)2) Create the spring config xml file 'grails-app/conf/resources.xml'Note: As of grails 1.2 the component-scan will not be needed as grails supports the@Component annotation by default
- 22. Create a AnnotationWe create a Cacheable annotation under src/java.
- 23. We create a AspectWith the above, any method with the annotation @Cacheable will be handled by the aroundAdvice method. For now we just called proceed() so the method We are intercepting is executed and we return the value
- 24. Trivial CachingAs we apply 'around' advice to our method it is trivial to cache.Check if we have a cached valueIf not execute method and store resultelse load cached itemReturn resultFor this example grails comes with the oscache libs already so I'll use that for the caching
- 26. Trivial Caching (cont)Below is the function we use to generate the cache key based on method name / arguments
- 27. ConclusionWe've seen how Grails integrates withJavaSpringThe rapidness of creating a applicationIf you have a spring application already you can import your spring beans into GrailsBoilerplate code has gone, no more days lost setting up new projects writing masses of XML
- 28. Points not DiscussedScaffoldingGrails attempts to create basic views of your domain to get you startedGORM
- 29. Questions