Play! Framework for JavaEE Developers
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User.getUser(Long id) and User.getUsers(Long page, int cnt) methods retrieve data from the cache using different keys. So modifying and saving an object retrieved by getUser does not update the cached collection returned by getUsers, leading to inconsistencies. Play's caching at the model level does not consider relationships between entities.
Play! Framework for JavaEE Developers
- 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/[email protected]
- 5. Too old , cumbersome
- 6. Tapestry (old experience, T5 is very good)
- 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
- 30. Unless you use a full-fledged JavaEE Server (Glassfish or WebLogic ...)
- 31. Layered
- 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 : ${user.name}http://localhost:9000/hello
- 36. And Play is ...A full stack framework (platform)
- 37. Totally independent of JavaEE environment
- 38. RESTful
- 39. No session
- 40. Stateless
- 41. Pure server side
- 42. Similar to Rails / Django
- 44. Unlike JavaEE's anemic domain modelFull Stack Framework?Bundles compiler , embedded server , hibernate , logger , test runner , email , groovy template engine, scala...
- 45. Can be packaged as a WAR and deployed to servlet containersPlay! A Glued Pure Web FrameworkShallow!Most libs are directly exposed to Play! & replaceableWhere Magic Happens
- 46. Play! URLs are RESTful & SEO-friendlyUGLYGRACEFUL/car/1
- 50. /car.jsp?id=1
- 52. http://www.facebook.com/ photo.php? fbid=2121715487568& set=o.172881386106136& type=1&theaterPlay is not based on ServletMany java server side frameworks (Spring MVC / Struts / Wicket / JSF / Tapestry ...) are based on servlets, but Play! is not!You cannot do such things :session.setAttribute("user" , user);
- 53. Use HttpSessionListener to count sessions (online users)
- 54. ServletFilter
- 56. @ServletSecurity
- 57. <auth-constraint /> , <security-role />Play! is StatelessPlay! shares nothing between each request!
- 58. The most important feature you have to keep in mind
- 59. No session!
- 60. Session is the source of all problems of the JavaEE platform!
- 62. Sticky session
- 63. Play uses (delegates to) memcached to eliminates such headachesPlay's Informative Error Page
- 64. Play's Domain Objects Are RichPlay*Spring promoted JavaEEUser extends ModelUser extends ObjectUserDao.javasave(User u)User u = new User(...)u.save()UserDaoImpl implements UserDaovoid setEntityManager(...)
- 65. save(User u)Client.java@Inject UserDao userDaoUser u = new User(...)userDao.save(u)VS*JPA advocates eliminating the DAO layer
- 66. Play's Architecture$ play new myprojmyprojappcontrollersmodelsconfapplication.confviewsmessageslibfooroutesmodulesbarpublicimagesjavascriptssrcstylesheets
- 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)} ${car.name} #{/a}#{/list}template [email protected](car.id)
- 76. How objects are passed to View !?controllers/App.javapublic static void showUser(Long uid) { renderArgs.put("user",u); render(cars , ...); }!!??views/App/showUser.html${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$RenderArgs;"), "current"); renderargs.put("user", u); render(new Object[] { cars }); } break MISSING_BLOCK_LABEL_120; Exception exception; exception; Object obj1 = null; play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.exit(); throw exception; Object obj2 = null; play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.exit(); return;}
- 78. Who Modifies My Code !?Who ?Play's custom classloader & JDT & javassistWhen ?DEV mode : When you modify the code and reload the page
- 79. PROD mode : App's start timeHow ?At compile time , some classes are enhanced by play.classloading.enhancers.* (powered by javassist)
- 83. LocalvariablesNamesEnhancer, ...Impact ?Rapid development time !View Templateobject path${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
- 133. Standard
- 134. Strict
- 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