• Overview & Application structure
• MVC architecture explained: Controller, View, Model
• Validation, Jobs, Asynchronous requests, Caching
• Modules and Plugins, Dependency Management, Testing
• Production Setup, Monitoring
• Coding Workshop

• Studied information systems
• 10 years linux system engineering, converted to software engineering
• Web framework enthusiast, fed up with complex java environment for simple webapps
• Other interests: Scaling web architectures, Web 2.0 (nosql, search)
• Started with play 1.0 in 2009, started writing cookbook in dec 2010
• Working at Lusini GmbH, building an ecommerce platform
• Streetball/Basketball

• Web as ubiquitous platform
• Providing data, not web pages
• Browser as the operating system
• JavaScript gains steam, toolkits as well as engines
• Web applications are alive

• No compile, deploy, restart cycle - Fix the bug and hit reload!
• Share nothing system - no state in the server
• Clean templating system - using groovy
• Exact errors (including line numbers, even for templates)
• Lots of builtin features for fast development
• Pure Java
• Starts fast, runs fast
• Extensible by modules
• WebSocket support, no servlet support

• Exists since 2008, by Guillaume Bort from zenexity
• Releases
  • 1.0 in October 2009
  • 1.1 in November 2010
  • 1.2 in April 2011
• Current: 1.2.4 + development tree + play-scala
• Play 2.0 preview is available

• REST as architectural paradigm for ressources
• URLs are the entry point (and implicit interface) to your application
• Do not work against HTTP (stateless protocol)
• Convention over configuration
• Only fractions of differences between development and production mode

• Hibernate, JBoss Netty, log4j
• Oval, Lucene, Gson
• Eclipse compiler, ivy, xstream
• Apache Commons: fileupload, httpclient, email, logging, beanutils
• EhCache, JAMon, Groovy, javassist
• c3p0, joda time, htmlunit

• conf
  • application.conf
  • routes
  • dependencies.yml
  • messages
• app
  • models
    • User.java
    • Message.java
  • controllers
    • Application.java
  • views
    • Application
      • index.html
• test
• lib
• public
• modules

• Configure database access (via JDBC):db=fs, db=mem db=mysql:user:pwd@database_name
• I18N
• Logging, Caching, Mail configuration
• Node & system specific settings
• Module specific configuration

    GET     /                 Application.index
GET     /user/{username}  Application.showUser
POST    /user             Application.createUser
DELETE  /user/{username}  Application.deleteUser
GET     /public           staticDir:public
    

public class Application extends Controller {
  public static void index() {
    List<User> users = User.findAll();
    render(users);
  }
}

  public static void showUser(String username) {
    User user = User.find("byUsername", username).first();
    notFoundIfNull(user);
    render(user);
  }

  public static void deleteUser(String username) {
    User user = User.find("byUsername", username).first();
    notFoundIfNull(user);
    user.delete();
    index();
  }

  public static void createUser(@Valid User user) {
    if (validation.hasErrors()) {
      flash.error("Invalid user data");
      Application.index();
    }
    user = user.save();
    Application.showUser(user.username);
  }

  public class AuthController extends Controller {
	
  @Before(unless = "login")
  public static void checkSession() {
    if (!session.contains("username")) {
      forbidden("You are not authorized");
    }
  }

  public void login(String username, String password) {
    User user = User.find("byUsernameAndPassword",
      username, Crypto.passwordHash(password)).first();
    notFoundIfNull(user);
    session.put("username", user);
    Application.index();
  }

#{extends ’main.html’ /}
<ul>
#{list items:users, as:’user’}
  <li>
    #{a @Application.showUser(user.username)}
      ${user.username}
    #{/a}
  </li>
#{/list}
</ul>

#{form @Application.createUser()}
Username: <input type="text" name="user.username" />
Password: <input type="pass" name="user.password" />
Email: <input type="text" name="user.email" />
<input type="submit" value="Add user" />
#{/form}

• doLayout, extends, include
• if, ifnot, else, elseif
• &{’i18nVariable’} out of conf/messages.de
• Always access to: session, flash, request, params, lang, messages, out, play

public class SqrtExtension extends JavaExtensions {
  public static Double sqrt(Number number) {
    return Math.sqrt(number.doubleValue());
  }
}

<div>
Square root of ${x} value is: ${x.sqrt()}
</div>

@Entity public class User extends Model {
  @Required @Column(unique = true)
  public String username;
  
  @Required @Email
  public String email;
  
  @Required
  public String password;
}

User user = User.find("byUsername", username).first();
user.password = "foobar"; // setter call
user.save();

List<User> users = User.findAll();
users.get(0).delete();

List<String> names = User.find("select u.username from User u
 order by u.username desc").fetch();

• Scheduled jobs (housekeeping)
• Bootstrap jobs (initial data initialization)

/* @Every("1h"), @OnApplicationStop, @On("0 0 12 * * ?") */
@OnApplicationStart
public class LoadDataJob extends Job {
  public void doJob() {
    /* .. do whatever you want */
  }
}

• Asynchonous operations allows to reuse the connection thread pool while the request is not closed
• Inherits from Future, onRedeem() is executed on arrival
• play.libs.F: Promise.waitAll(), Promise.waitAny()

public static void renderPdf() {
  InputStream is = await(new PdfRenderJob().now());
  renderBinary(is);
}

public static void getResponses() {
  Promise r1 = WS.url("http://www.google.de").getAsync();
  Promise r2 = WS.url("http://www.lycos.de").getAsync();
  List<HttpResponse> responses = 
      Promise.waitAll(r1, r2).getOrNull();
  render(responses);
}

• String f = Cache.get("id", String.class);
• Cache.set("id", "someId", "5mn");
• Writing your own implementation is implementing one interface
• Existing implementations: EhCache (default), memcached, hazelcast

memcached=enabled
memcached.host=127.0.0.1:11211

/* caches the whole result */
@CacheFor("5s")
public static void time() {
    /* HTTP header Cache-Control: max-age: 1 */
    response.cacheFor("1s");
    renderText(new Date());
}

• Make sure no expensive computation happened in the controller
• Fetching 1000 entities in the controller, then using the cached version in the template is useless

#{cache 'currentTime', for:'3s'}
   ${new java.util.Date()}
#{/cache}

• Modules provide arbitrary extensions (HTML, CSS, Java, deployment helpers, i18n, URLs)
• Modules are mini applications inside your application
• Packaged as zip file, fetched from repository
• Currently there are more than 100 modules, but still far from the rich grails eco system
• Plugins are java classes inheriting from PlayPlugin and extending functionality of an application via hooks

• play.PlayPlugin is the key class, has a priority
• Startup: onLoad(), onApplicationStart(), afterApplicationStart(), onApplicationStop(), onConfigurationRead(), onRoutesLoaded(), onApplicationReady(), afterFixturesLoad()
• Status: getStatus(), getJsonStatus()
• Objects: enhance(), bind(), unbind(), getMessage()
• Events: onEvent, PlayPlugin.postEvent()

• Invocation: rawInvocation(), beforeInvocation(), afterInvocation(), onInvocationException(), invocationFinally(), onInvocationSuccess()
• Action Invocation: beforeActionInvocation(), onActionInvocationResult(), afterActionInvocation()
• Template: loadTemplate(), overrideTemplateSource(), addTemplateExtensions(), addMimeTypes()

• Development: detectChange(), detectClassesChange(), beforeDetectingChanges(), onClassesChange()
• Requests & routing: serveStatic(), onRequestRouting(), routeRequest()

• Based on Apache Ivy, but using YAML
• Configuration file: conf/dependencies.yml
• play deps --sync

require:
    - play
    - play -> crud
    - play -> cobertura 2.1
    - org.elasticsearch -> elasticsearch 0.17.2

• Maven or custom repositories can be added (URL layout can be configured)

repositories:
    - sonatype:
        type: iBiblio
        root: "http://oss.sonatype.org/content/repositories/releases"
        contains:
            - org.elasticsearch -> *

• Unit tests
  Standard junit tests extending from UnitTest - need a JPA environment
• Functional tests
  Integration tests checking the HTTP responses and their contents
• Selenium tests
  GUI tests. Very nice controllable, in-browser playback recorder
  Possibility of doing step-by-step slow debugging
• Cobertura module, spock plugin

User(aleree):
  username: alr
  password: test
  email   : alexander@reelsen.net

@Before public void setUp() {
  Fixtures.deleteAll();
  Fixtures.load("data.yml");
}

public class BasicTest extends UnitTest {
    @Test
    public void testThatSomethingInTheModelWorks() {
        // Model tests go here
    }
}

public class ApplicationTest extends FunctionalTest {
    @Test
    public void testThatIndexPageWorks() {
        Response response = GET("/");
        assertIsOk(response);
        assertContentType("text/html", response);
        assertCharset("UTF-8", response);
    }
}

• Own methods to receive emails and access the cache in tests
• Play Selenium Plugin for Firefox

#{fixture delete:'all', load:'data.yml' /}

#{selenium}
    open('/')
    assertNotTitle('Application error')
#{/selenium}

• Calimoucho, runs also on integration.playframework.org
• Hudson plugin
  Runs play auto-test

• No servlet container or application server needed
• Deploying into a servlet container is supported but not recommended
• SSL support built-in
• Serving static files is faster with apache or nginx
• Several environments in one configuration file possible
• Support for automatic deploying into GAE, Heroku, Stax, capistrano, dotcloud, cloudbees, playapps, cloudfoundry

application.name=My application
%test.application.name=Test application
%prod.application.name=Production application

• The session cookie is signed but not encrypted!
• The template engine automatically escapes strings
• SQL injection is only possible when writing own JPA queries
• CSRF: Use of authenticity token

• Provides information about your application state
• JVM infos, Play version, running threads and application configuration information
• Loaded modules, loaded plugins (order)
• Datasource, Jobs, execution pool information
• Detailed information about controller runtimes and template rendering times, including min/max/avg values

MonitorFactory.add("CacheHitsFoo", "cnt", 1);

Monitor monitor = MonitorFactory.start("RemoteApiCall");
/// … logic goes here
monitor.stop();

• Play 2.0 is coming, available as preview
• 1.x will be supported and developed as well
• The core will be more scala, but Java and Scala will be used
• Typesafe template engine, typesafe router (more performance)
• No more Hibernate (ebean as replacement)
• SBT as build system
• Native Akka support
• Built-in LESS and coffeescript support

• Playframework
• Twitter: @playframework
• My presentations at slideshare
• German: Articles from 2009 in kaffeeklatsch magazine (part 1, part 2)
• Play framework cookbook (example sources on github)
• Presentation has been done with shower

git clone git://github.com/playframework/play play
cd play
git checkout remotes/origin/1.2.x
cd framework
ant

git clone git://github.com/spinscale/play-bidding-sample