Play! Framework for JavaEE Developers

1. JavaTWO專業技術大會

2. Play!Framework for JavaEE Developers

3. Who am IExp : JSP/Servlet , Tapestry , Spring/Hibernate/JavaEE , Wicket , Android , Grails , Play! Frameworkhttp://gplus.to/smallufohttp://twitter.com/smallufosmallufo@gmail.com

4. Web Framework ExperiencesJSP/Servlet

5. Too old , cumbersome

6. Tapestry (old experience, T5 is very good)

7. Complicated , evolution/deprecation too fast

8. Wicket

9. Too elaborate , fail to see the wood for the trees

10. May lead to over-engineered architecture for OO-purism

11. Spend too much time refactoring

12. Maybe web component reuse is just a myth

13. Grails (old experience, without Groovy++)

14. Slow

15. Too many inconsistent DSLs (URL-mapping , DB , logging...)

16. Not Java , IDE unfriendlyConventional JavaEE Stack

17. Conventional JavaEE StackWant standard page ?

18. Let's define JSP/JSTL (JSR-53)

19. And let Apache (or others) to implement Jakata Taglibs

20. Want web components ?

21. Let's define Java Server Faces (JSR-127)

22. And let communities to implement MyFaces, PrimeFaces, ICEfaces...

23. Want restful ?

24. Let's define JAX-RS (JSR-311)

25. And let communities to implement CXF, Jersey, RESTEasy, Wink...Conventional JavaEE StackLots of ...

26. Specs

27. Implementations

28. Configurations

29. Tedious , Error-prone

30. Unless you use a full-fledged JavaEE Server (Glassfish or WebLogic ...)

31. Layered

32. Defined by Standards/Specs

33. Assembled by InterfacesOVER ARCHITECTED

35. Play’s App Looks Like ?conf/routesapp/App.javaGET /hello App.hellopublic class App extends Controller { public static void hello() { User user = User.findById(1L); render(user); }} views/App/hello.htmlHello World : ${user.name}http://localhost:9000/hello

36. And Play is ...A full stack framework (platform)

37. Totally independent of JavaEE environment

38. RESTful

39. No session

40. Stateless

41. Pure server side

42. Similar to Rails / Django

43. Rich domain model

44. Unlike JavaEE's anemic domain modelFull Stack Framework?Bundles compiler , embedded server , hibernate , logger , test runner , email , groovy template engine, scala...

45. Can be packaged as a WAR and deployed to servlet containersPlay! A Glued Pure Web FrameworkShallow!Most libs are directly exposed to Play! & replaceableWhere Magic Happens

46. Play! URLs are RESTful & SEO-friendlyUGLYGRACEFUL/car/1

47. /listcar/page1/count10

48. /listcar/page1?count=10

49. /listcar/page/1/count/10

50. /car.jsp?id=1

51. /listcars.jsp?page=1&count=10

52. http://www.facebook.com/ photo.php? fbid=2121715487568& set=o.172881386106136& type=1&theaterPlay is not based on ServletMany java server side frameworks (Spring MVC / Struts / Wicket / JSF / Tapestry ...) are based on servlets, but Play! is not!You cannot do such things :session.setAttribute("user" , user);

53. Use HttpSessionListener to count sessions (online users)

54. ServletFilter

55. Servlet-related securities

56. @ServletSecurity

57. <auth-constraint /> , <security-role />Play! is StatelessPlay! shares nothing between each request!

58. The most important feature you have to keep in mind

59. No session!

60. Session is the source of all problems of the JavaEE platform!

61. Session replication

62. Sticky session

63. Play uses (delegates to) memcached to eliminates such headachesPlay's Informative Error Page

64. Play's Domain Objects Are RichPlay*Spring promoted JavaEEUser extends ModelUser extends ObjectUserDao.javasave(User u)User u = new User(...)u.save()UserDaoImpl implements UserDaovoid setEntityManager(...)

65. save(User u)Client.java@Inject UserDao userDaoUser u = new User(...)userDao.save(u)VS*JPA advocates eliminating the DAO layer

66. Play's Architecture$ play new myprojmyprojappcontrollersmodelsconfapplication.confviewsmessageslibfooroutesmodulesbarpublicimagesjavascriptssrcstylesheets

67. conf/application.confapplication.name=myappapplication.mode=devapplication.secret=OOXXOOXXOOXXOOXXOOXXhttp.port=9000java.source=1.6db.url=jdbc:mysql:...db.driver=com.mysql.jdbc.Driverdb.user=userdb.pass=passhibernate.use_sql_comments=truehibernate.format_sql = trueXForwardedSupport=127.0.0.1

68. Play's ArchitecturecontrollersappMyController.javapublic static void index()public static void show()modelsviewsMyControllerindex.htmlfooshow.htmlbar

69. conf/routesHTTP methodURI PatternActionGET / App.indexPOST /login App.loginGET /tag/{name} App.tag(name)GET /list/{page} App.list(page)GET /list/{<[0-9]+>page} App.list(page)GET /list/{page}/{count} App.list(page,count)GET /public/ staticDir:public* /{controller}/{action} {controller}.{action}

70. Play's Request Life Cycle

71. Controllers and Redirectionspublic class App extends play.mvc.Controller { public static void index() { render(); // views/App/index.html contains a login form } public static void login(String name,String passwd) { if(...) // success welcome(); else // failed index(); } public static void welcome() { render(); // renders views/App/welcome.html }}

72. Controller Interceptionspublic class App extends play.mvc.Controller { @play.mvc.Before(unless={“index”, “login”}) public static void intercept() { if (session.get("uid")==null) index(); } public static void index() {...} public static void login(String name,Stringpasswd){..} public static void welcome() {...}}

73. Session : A Signed Cookiepublic static void login(String name , String passwd) { User u = ... if (...) { session.put("uid" , u.id); }}Only put index data to sessionNever store sensitive datasigned, uneditable!

74. Controller Revisitedpublic static void show(Long uid, String type) { User u = ... if (type.equals("json") { renderJSON(u); // provided by GSON } else if (type.equals("xml") { renderXml(u); // provided by XStream } render(u); }Why not continue rendering?play.mvc.Controllerthrow new RenderJson(jsonString);throw new RenderXml(xml);throw new RenderTemplate(...);

75. Controller and Viewcontrollers/App.javapublic static void showUser(Long uid) { User u = ... List<Car> cars = ... renderArgs.put("user",u); render(cars, company, job, ...); }public static void showCar(Long id) {...}renderArgs.put(“cars”,car);renderArgs.put(“company”,company);renderArgs.put(“job”,job);sameviews/App/showUser.htmlHello ${user.name} , these are your cars :#{list items:cars , as:'car'} #{a @showCar(car.id)} ${car.name} #{/a}#{/list}template tag@App.showCar(car.id)

76. How objects are passed to View !?controllers/App.javapublic static void showUser(Long uid) { renderArgs.put("user",u); render(cars , ...); }!!??views/App/showUser.html${user.name}#{list items:cars , as:'car'}Let's decompile it...

77. public static void showUser(Long uid){ play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.enter(); play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.addVariable("uid", uid); if(!play.classloading.enhancers.ControllersEnhancer.ControllerInstrumentation.isActionCallAllowed()) { Controller.redirect("controllers.App.showUser", new Object[] { uid }); } else { play.classloading.enhancers.ControllersEnhancer.ControllerInstrumentation.stopActionCall(); User u = (User)User.findById(uid); play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.addVariable("u", u); List cars = Car.all().fetch(); play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.addVariable("cars", cars); Object obj = null; play.mvc.Scope.RenderArgs renderargs = null; renderargs = (play.mvc.Scope.RenderArgs)Java.invokeStatic(Desc.getType("Lplay/mvc/Scope$RenderArgs;"), "current"); renderargs.put("user", u); render(new Object[] { cars }); } break MISSING_BLOCK_LABEL_120; Exception exception; exception; Object obj1 = null; play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.exit(); throw exception; Object obj2 = null; play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.exit(); return;}

78. Who Modifies My Code !?Who ?Play's custom classloader & JDT & javassistWhen ?DEV mode : When you modify the code and reload the page

79. PROD mode : App's start timeHow ?At compile time , some classes are enhanced by play.classloading.enhancers.* (powered by javassist)

80. ContinuationEnhancer

81. ControllerEnhancer

82. PropertiesEnhancer

83. LocalvariablesNamesEnhancer, ...Impact ?Rapid development time !View Templateobject path${objectname}${object.property}implicit objects${params.userId}${session.userId}${request.userId}built-in tags#{if} ... #{/if} #{else}... #{/else}#{list items:users , as:'user'} ${user.name}#{/list}#{a @App.showUser(user.id)} show user #{/a}#{form @App.login() } ... #{/form}

84. Rich Domain Object Modelpackage models;@javax.persistence.Entitypublic class User extends play.db.jpa.Model { public String username; public String password;}Support JPA's annotations : @Column , @ManyToOne , @OneToMany ...NO more getters & setters... Great !

85. Rich Domain Object ModelBUT...The underlayer is hibernate & hibernate needs getter/setterAgain...Who modifies my model ?

86. Rich Domain Object ModelIn Fact... Your model still contains getter/setter , modified by Play's custom classloader & JDT & javassistUser.javapublic String getUsername() { return "overridden";}${user.username} will be ??

87. Rich Domain ObjectUser u = User.findById(1);User u = User.find("byUsernameAndPassword", username , password).first();User u = User.find("select u from User u where u.username = :username and u.password = :password") .bind("username",username) .bind("password",password) .first();List<User> users = User.all().fetch();User.em().createQuery(...);

88. Validations : Controller#{form @App.login()} <p>username <input type=“text” name=“username” value=“${flash.username}” /> <span class=“error”>#{error 'username'/}</span> </p> <p>password <input type=“password” name=“password” value=“${flash.password}” /> <span class=“error”>#{error 'password'/}</span> </p> <input type="submit" value=“Login" /> <span class=“error”>#{error ‘other'/}</span>#{/form}username請輸入帳號password請輸入密碼Login帳號或密碼輸入錯誤

89. Validations : Controllerpublic static void login(@Required(message ="請輸入帳號")String username, @Required(message ="請輸入密碼")String password) { User user = User.login(username , password); if (validation.hasErrors()){ params.flash(); // add parameters to flash scope validation.keep(); // keeps the errors flash.error(validation.errors().get(0).toString()); render(“pleaseLogin.html”); } flash.success(“welcome : “ + user.username); render();}

90. Validation : Modelpublic class User extends Model {@Required @MinSize(6) public username;@Required @MinSize(6) public password; public static User login(String username , String password) { Validation validation = Validation.current(); User user = ... validation.isTrue(user!=null) .key(“other”).message(“帳號或密碼輸入錯誤”); return user;}}Will @MinSize affect login() ?

91. Validations@Required , @Min , @Max , @MinSize , @MaxSize , @Range , @Email , @URL ...Custom validation annotationextends AbstractAnnotationCheck & implements isSatisfied()i18n messages/conf/messages

92. CacheConventional JavaEE's Waypublic User getUser(String name) { Session s = (Session)em.getDelegate(); Criteria c = s.createCriteria(User.class); c.add(Restrictions.eq("username",name); c.setMaxResults(1); c.setCacheable(true); if (c.uniqueResult() == null) return null; return (User) c.uniqueResult();}

93. CachePlay's Way : Not In Favor of 2nd Levelpublic static User getUser(String name) { String key="username_"+name; User user = Cache.get(key,User.class); if (user != null) return user; user = User.find("byUsername",name).first(); Cache.set(key,user,"30mn"); return user;}

94. Cache - Problem !User.java { public static User getUser(Long id) { String key = "userId_"+id; ... } public static List<User> getUsers(Long page, int cnt) { String key="users_"+page+"_"+cnt; ... }}public interface UserDao.java { public User getUser(Long id); public List<User> getUsers(Long page, int cnt);}

95. Conventional JavaEE's WayUser u1 = userDao.getUsers(1,10).get(0);User u2 = userDao.get(1L);assertTrue(u1.equals(u2)); // PASSEDu2.modifySomething(...);userDao.save(u2);User u3 = userDao.getUsers(1,10).get(0);assertTrue(u3.equals(u2)); // PASSEDPlay's WayUser u1 = User.getUsers(1,10).get(0);User u2 = User.getUser(1L);assertTrue(u1.equals(u2)); // PASSEDu2.modifySomething(...);u2.save();User u3 = User.getUsers(1,10).get(0);assertTrue(u3.equals(u2)); // FAILED!

96. Cache Problem : Reason users_1_10cache key :TIMEuuuuuuuuuuu1userId_1cache key :umodified / updatedu2users_1_10cache key :?uuuuuuuuuu3

97. Cache - Problem! How to Solve It ?Ignore it , accept it

98. Never cache sensitive data

99. Two phase list retrieval

100. Cache object ids instead of objectspublic static List<User> getUsers(Long page, int cnt) { String key="users_"+page+"_"+cnt; List<Long> userIds = User.find("select u.id from User u) .fetch(page,cnt); Cache.set(key, userIds, "1mn"); // iterate each id in result and query cache or fetch}

101. Cache : Wait... I saw Model.em() ? How about get underlaying Hibernate’s session and setCacheable(true) ?Session s = (Session) User.em().getDelegate();Critieria c = s.createCriteria(...);c.add(... criterions ... );c.setCacheable(true);

102. Play's Module System

103. Module : CRUDpackage models;public class User extends Model { ... }package controllers;public class Users extends CRUD { ... }Cars , Photos , Logseven ...Boxs , Buss, Kisss

104. Module GAE + Module Sienapublic class User extends siena.Model { public String uid; public static User getUser(String uid) { return User.all(User.class).filter("uid",uid).get(); } public static User getUsers(int page , int count) { return User .all(User.class) .fetch(count,(page-1)*count); }}Don't forget war/WEB-INF/appengine-web.xml$ play gae:deploy Done !

105. Play on GAESimplest way to deploy Java Apps on GAE !

106. Shortest cold start time

107. Less than 10 seconds

108. Cache is wrapped to GAE's memcache

109. Mail is wrapped to GAE's mail serviceIssue : Portal-like PageMany blocks query DB in every page

110. Passing these query results in every action is cumbersome

111. Solution : @Before and renderArgs.put()@Beforestatic void addDefaults() { renderArgs.put("brands", Brand.all().fetch()); renderArgs.put("forums", Forum.getAll()); renderArgs.put("tags" , Tag.getAll());}

112. Issue : High Availability<VirtualHost *:80> ServerName myapp.com <Location /balancer-manager> SetHandler balancer-manager Order Deny,Allow Deny from all Allow from .myapp.com </Location> <Proxy balancer://mycluster> BalancerMember http://localhost:9002 BalancerMember http://localhost:9003 status=+H </Proxy> <Proxy *> Order Allow,Deny Allow From All </Proxy> ProxyPreserveHost on ProxyPass /balancer-manager ! ProxyPass / balancer://mycluster/ ProxyPassReverse / http://localhost:9002/ ProxyPassReverse / http://localhost:9003/</VirtualHost>Apache Web Serverlocalhost:9002localhost:9003Same directory structures & application.secret , only different http.port

113. Issue : Action Burstcontrollers/Appcontrollers/Applogin()logout()register()myaccount()mybooks()index()page()search()showbook()login()logout()register()myaccount()mybooks()index()page()search()showBook()listUsers()editUser()editBook()controllers/AdminlistUsers()editUser()editBook()

114. Issues : Validation DilemmaValidation in controllers ?validation in models ?or hybrid ?

115. Issue : DIDependency Injection is not so useful in Play’s Rich Domain Object environment

116. Case Study : VAGTW.COMVW/Audi Car Problem Stats

117. vagtw.com Data Model

118. VAGTW.com developmentDev in one month (Since 2010/4/1)

119. Modified from Play's YABE sample

120. 10 days learning Play! & modeling & coding

121. 20 days tuning HTML & CSS(3)

122. 2010/5/1 Debut

123. Peak 4x users in 15 mins

124. Indexed by Google in 2 days

125. Indexed by Yahoo in 2 weeks

126. Indexed by Bing after 2 monthsConclusionsIS ...A Glued Pure Web Framework

127. Loose

128. Shallow

129. non-Standardized

130. Page-based

131. StatelessIS-NOT ...A Java library

132. Full-Fledged JavaEE stack

133. Standard

134. Strict

135. Defined-assembled by interfaces

136. Component-based

137. Stateful (Session-aware)Conclusions : Use Play! If You...Have to prototype or build something quicklyDon’t want to buy high-priced Java application serversAre not so OO-purism, feel OK without interfacesMany Play’s “hook” are not enforced by abctract mathods or interfacesKnow JavaScript & other JS frameworksYou can build slick UIs without sluggish server-state implementation responses (Wicket/JSF...)Feel OK about object inconsistences in cacheWant to develop GAE appsYour team have a strong mendiatorBecause programming in play is too unrestrainedWant to learn Scala

138. 小心回不去了

Play! Framework for JavaEE Developers

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Play! Framework for JavaEE Developers