Andre Steingres on Grails

Transcript

1. The  Search  is  Over
2. Grails  Inside  -­‐  Grails,  Groovy  and  Related  Technologies http://andresteingress.wordpress.com
4. @sternegross Andre  Steingress
5. Hire me!
7. GRAILS
8. An  Overview
9. YAWAFW (?) Let‘s make a step backwards So you like coding stuff, huh? If yes, what coding related work bothers you the most? If no, time to leave now.
10. YAWAFW (?) Other 14 % Domain 6 % Infrastructure 80 %
11. • Ruby on Rails hits the road in 2004 • Innovative Philosophies • Convention over Configuration • Don‘t Repeat Yourself • Code Templates • Easy DB Integration • Ruby as Dynamic Programming Language YAWAFW (?)
12. YAWAFW (?) What about the Java world?
13. • Grails hits the road in 2006 • Taking full advantage of Groovy, a dynamic language for the JVM • Built on JEE, Spring, Hibernate and other popular libraries/frameworks you love (or hate) • Turbo-Charging Existing Development Knowledge • Current Version: 1.3.2
15. The  Tools
16. grails
17. • grails-app - „Convention over Configuration“ • lib - additional libraries • scripts - custom Grails scripts/commands • src - Java/Groovy source • test - integration, unit tests • web-app - CSS, images, JS, custom context.xml, etc. A Generated Grails App
18. grails create-domain-class
19. Domain Class
20. Unit Test
21. Domain Class
22. Unit Test
23. grails test-app
24. grails console
25. • Next Steps: • generate-all ... generates views + controller • run-app ... runs app in embedded tomcat • war ... generates WAR archive grails
26. grails run-app
27. grails haz command? • grails <some GAnt script name> • help, create-app, create-domain-class, etc. • implemented as GAnt scripts • $GRAILS_HOME/scripts
28. grails haz command? • default container: tomcat grails install-plugin jetty
29. IDE Integration • STS • Netbeans • IntelliJ • Textmate with Groovy/Grails tmbundle
31. The  Framework
32. • building blocks: Spring Framework, Hibernate and Groovy • GORM - Extension to Hibernate • Dynamic Finders: Blog.findByTitleLike, Blog.findByDateCreatedBetween(x, y) • Criteria DSL • HQL: Blog.findAll(„from Blog b where b.title like ?“, [title]) • GSPs, Tag Libraries, Filters • Grails provides configuration DSLs for Spring, Log4J, DataSource, WebFlow, etc. • Environments: development, test, production
33. • Bootstrap Script in conf/BootStrap.groovy • Codecs: encodeAsHtml, encodeAsJavascript, encodeAsMD5, ... • XML/JSON Marshalling • Plugin System • Dependency Management with Ivy (conf/BuildConfig.groovy)
34. Artefacts
35. • Convention over Configuration • def. Artefact: „is any object made or modified by a human“ • important Grails Artefacts: Domain Classes, Services, Controllers • subfolders: domain, controllers, services • each Grails artefact has a distinguished artefact handler • command line tools: create-domain-class, create-service, create-controller • Plugins might register other Grails artefacts: e.g. Quartz registers the „job“ artefact
36. Domain Classes • POGOs == Plain Old Groovy Objects • holds constraints and GORM configurations
37. Services • public methods run in transactional contexts • fine-grained configuration with @Transactional • scoped services: prototype, request, flash, etc.
38. Controllers • Extended persistence context aka OpenSessionInView • flash scope, logger injection, model chaining, etc.
39. So what? • Spring, Hibernate & Groovy are the underlying foundation of Grails • Java is the underlying foundation of Groovy
40. Languages
42. • DSL == Domain Specific Language • Groovy has a MOP, makes building custom DSLs super easy! • Meta Object Protocol • adaptable runtime behavior through the metaClass property • GroovyObject, ExpandoMetaClass, custom MetaClass, Categories, ... • methodMissing/propertyMissing • Support for compile-time meta-programming: AST transformations
48. • Logging DSL in conf/Config.groovy
49. • Found in Log4jConfig.groovy used by LoggingGrailsPlugin • Delegates all method calls in the DSL to Log4jConfig instance
51. • Spring DSL in conf/resources.groovy
52. So what? • Groovy‘s meta capabilities are the underlying foundation of DSLs
53. Plugins
54. • grails create-plugin BlogDomain • same directory structure as a Grails application + *Plugin.groovy
56. • Structuring applications with Grails plugins • Since 1.3: support for publishing to Maven/SVN repos • http://grails.org/plugin/home - 435 plugins, SVN based repo
57. Internals
58. • Grails application == Spring MVC web application • WEB-INF/applicationContext.xml
59. • GrailsApplication • main interface representing a running Grails application • artefact management • implements GroovyObjectSupport: application.domainClasses, application.controllerClasses etc. • GrailsRuntimeConfigurator • creates the application‘s WebApplicationContext • registers/inits additional plugin artefact handler instances • executes plugin runtime configuration: doWithSpring • loads legacy Spring application contexts from conf/spring/resources.xml
60. • It‘s spring, baby!
61. Conclusio
62. • Like • fast bootstrapping of new projects • large plugin ecosystem • component modularization with versioning out-of-the-box • Groovy, a real dynamic programming language, kicks ass • built on top of Spring Framework and Hibernate • GORM saves a lot of DAOs • Testing using a dynamic programming language is fun • Reuse existing Spring/Hibernate artefacts (resources.xml, *.hbm.xml, etc.)
63. • Dislike • tool support is needed for larger projects • Groovy means performance overhead • exaggerated use of dynamic typing needs extensive testing
64. • Resources • Source Code • Grails Documentation (http://grails.org/doc/latest/) • Mailing Lists • Twitter • Literature
65. any  questions?
69. GContracts • Design by Contract(tm) for Groovy/Grails • Features • support for pre-/postconditions, class invariants • class invariants inheritance • pre-/postcondition inheritance • old and result variable in postcondition expressions
72. Want it? • use Groovy‘s @Grab • or define a [Maven|Ivy|...] dependency • or via direct download from http://github.com/andresteingress/gcontracts