Web application development using Play Framework (with Java)
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This document provides an overview of the Play Framework for web application development using Java. It discusses the history and architecture of Play, how to set up a Play project, the MVC structure, routing, controllers, views, sessions, assets, hot code reloading, databases, testing, deployment, and scaling. Play uses Netty as its web server, is stateless, supports hot code reloading, and allows building asynchronous and reactive applications. It also has integrations for Akka, WebSockets, caching, internationalization, and more.
Web application development using Play Framework (with Java)
- 1. Web application development using Play Framework (with Java) Tehran JUG meeting February-2015 By: Saeed Zarinfam
- 2. History Play 1 Created By Guillaume Bort at Zengularity SA in 2007 Play 2 release in 2012 by Typesafe (rewrite using Scala) Play 1 vs Play 2 Part of Typesafe Activator
- 3. Introduction • Inspired by Ruby on Rails and Django • Run on JVM (use java library) • MVC • Stateless • Hot code reloading (in development) • Convention over configuration • Lightweight • Asynchronous and Non-blocking I/O • Java 8 support
- 4. Architecture • MVC architecture • Netty as web server (no servlet container) • Sbt as build tools (Ivy dependency manager) • Stateless
- 5. Requirements Install Typesafe Activator (or sbt) JDK 6 or later activator new my-first-app play-java Open project in IDE (Eclipse and Intellij) Run using – command line (activator run) – Activator console (activator) – Activator UI (activator ui) – Interactive Console (Only in Scala)
- 6. Activator UI
- 7. Project structure • App • Public • Conf • build.sbt • Scala and Java • ...
- 8. Route • Scala syntax • Optional parameters • Reverse routing • REST friendly
- 9. Controller • Actions return Result • Static method • Use dependency injection (JSR 330 in Play 3) • HTTP manipulation (body parsers) – REST service (JSON and XML)
- 10. View Type safe template engine Scala Template (Twirl inspired by ASP.NET Razor) Http form handling
- 11. Session Session data are not stored in the server Session data added to each subsequent HTTP Request, using Cookie. Cookie are signed with a secret key so the client can’t modify the cookie data or it will be invalidated Use cache for sever side session data
- 12. Assets Public Assets WebJars Assets controller Etag Gzip Caching Managed Assets CoffeeScript LESS CSS Sbt-web plugins js-engine plugin (able to execute plugins written to the Node API either within the JVM via the excellent Trireme)
- 13. Hot code reloading (in development) It is possible because Play is stateless and tightly integration between Play and sbt Classloader hierarchy manage by sbt Tricky (You don't need JRebel) For each request reloader check if there's any code changes Compile changed codes remove the old application classloader create a new application classloader with the updated classes. restart application (only application, no need to restart the JVM)
- 14. Accessing Database JDBC JPA (2.0) Ebeans (default ORM) Database evolutions Connection Pool Transaction In-memory H2 database
- 15. Asynchronous Actions are asynchronous by default Each open connection does not need a thread application code should avoid blocking in controllers
- 16. Other APIs Integration with Akka WebSockets and Comet sockets Cache API Internationalization Interceptors Filters(only in Scala) JSON API (jackson) XML API Job scheduling (Using Akka) Logging API (Logback)
- 17. Testing Ready to use application stubs for test (several helper methods) Junit FEST assertions Mock Test every part of your application (router, action, controller and ...) Testing with a browser using FluentLenium ( Selenium WebDriver wrapper)
- 18. Plugins Several plugins – Mail – Open ID – CRUD – Security
- 19. Deployment Compile all class and assets in application Activator start Activator stage (without any dependency on Play) Activator dist (produces a ZIP file without any dependency on Play) SBT Native Packager plugin(activator universal:package- bin) – MSI, OS X disk image, RPM, DEB and … Publishing to a Maven (or Ivy) repository
- 20. Scaleability Scale horizontally easily (using load balancer) Integrate with Akka clustring and remoting features Asynchronous from bottom to top
- 21. Reactive Play Iteratee library (Scala Library) ReactiveMongo
- 22. Non-blocking ReturnPromise<Result>Promise<Result> Intensive computation will just be run on another thread (thread pool in separate execution context ). The web client will be blocked while waiting for the response, but nothing will be blocked on the server