Web development with the Play! framework
Java web development is fun again
Alexander Reelsen
alexander@reelsen.net
June 2010
Alexander Reelsen Web development with the Play! framework June 2010 1 / 35

Agenda
1 Introduction
Overview
2 Core concepts
Architecture
Conventions
Configuring routes
Model
Controller
View
Testing
Jobs
Running Play in production
3 Ongoing development
Features for Play 1.1
Module repository
Development forecast
Alexander Reelsen Web development with the Play! framework June 2010 2 / 35

Introduction
Agenda
1 Introduction
Overview
2 Core concepts
Architecture
Conventions
Configuring routes
Model
Controller
View
Testing
Jobs
Running Play in production
3 Ongoing development
Features for Play 1.1
Module repository
Development forecast
Alexander Reelsen Web development with the Play! framework June 2010 3 / 35

Introduction Overview
Speaking...
About me
Studied information systems
10 years linux system engineering, converted to software engineering
Just another java developer
Web framework enthusiast
Fed up with complex java environment for simple webapps
Non development life
Basketball/Streetball
Web 2.0
Alexander Reelsen Web development with the Play! framework June 2010 4 / 35

Introduction Overview
Speaking...
About me
Studied information systems
10 years linux system engineering, converted to software engineering
Just another java developer
Web framework enthusiast
Fed up with complex java environment for simple webapps
Non development life
Basketball/Streetball
Web 2.0
Alexander Reelsen Web development with the Play! framework June 2010 4 / 35

Introduction Overview
The web taking over
Ubiquitous web
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
Alexander Reelsen Web development with the Play! framework June 2010 5 / 35

Core concepts
Agenda
1 Introduction
Overview
2 Core concepts
Architecture
Conventions
Configuring routes
Model
Controller
View
Testing
Jobs
Running Play in production
3 Ongoing development
Features for Play 1.1
Module repository
Development forecast
Alexander Reelsen Web development with the Play! framework June 2010 6 / 35

Core concepts Architecture
Play in 10 seconds
Quick overview
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
Alexander Reelsen Web development with the Play! framework June 2010 7 / 35

Core concepts Architecture
Roots and fundamentals
History
Exists since 2008, by Guillaume Bort from zenexity
Release 1.0 was in October 2009
Current: 1.0.3 + development tree
A framework imposes its own style of architecture
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
Alexander Reelsen Web development with the Play! framework June 2010 8 / 35

Core concepts Architecture
Play architecture
Source: http://www.playframework.org/documentation/1.0.1/main
Alexander Reelsen Web development with the Play! framework June 2010 9 / 35

Core concepts Architecture
Play is a lot of glue code
Includes the following libraries
Hibernate
Oval
Lucene
Google gson
Eclipse compiler
Commons: fileupload, httpclient, email, logging, beanutils
MINA and Asyncweb
EhCache
JAMon
Groovy
Alexander Reelsen Web development with the Play! framework June 2010 10 / 35

Core concepts Architecture
Play specialties
Interesting to know
No support for servlet API (yes, in a web framework)
Sharing objects via memcached through several nodes
Everything is UTF-8
Full text indexing with 2 annotations
No anemic domain model - logic is in the object
DAOs and finders are not external
Textmate, eclipse bundles, also support for IDEA and netbeans
Alexander Reelsen Web development with the Play! framework June 2010 11 / 35

Core concepts Conventions
Application layout
Creating a new app
play new myapp
Application structure
./ conf
./ conf / routes
./ conf / a p p l i c a t i o n . conf
./ conf / messages
./ test
./ l i b
./ public
. / app
. / app / m o d e l s
. / app / c o n t r o l l e r s
. / app / v i e w s
Alexander Reelsen Web development with the Play! framework June 2010 12 / 35

Core concepts Conventions
Application layout
Creating a new app
play new myapp
Application structure
./ conf
./ conf / routes
./ conf / a p p l i c a t i o n . conf
./ conf / messages
./ test
./ l i b
./ public
. / app
. / app / m o d e l s
. / app / c o n t r o l l e r s
. / app / v i e w s
Alexander Reelsen Web development with the Play! framework June 2010 12 / 35

Core concepts Conventions
Application config file
conf/application.conf
Configure database access
db=fs, db=mem
db=mysql:user:pwd@database_name
Any JDBC connection
Specify modules
Supported languages
Logger
memcached setup
mail configuration
mode/system specific settings
Alexander Reelsen Web development with the Play! framework June 2010 13 / 35

Core concepts Configuring routes
The conf/routes file
Interface contract to the outer world
GET / Application . index
GET / u s e r /{ username } Application . showUser
POST / user Application . createUser
DELETE / u s e r /{ username } Application . deleteUser
GET / public staticDir : public
Alexander Reelsen Web development with the Play! framework June 2010 14 / 35

Core concepts Model
Designing a domain model
A simple user
@Entity
public class User extends Model {
@Required
@Column(unique = true)
public String username;
@Required
@Email
public String email;
@Required
public String password;
public void setPassword(String password) {
this.pass = Crypto.passwordHash(pass);
}
}
Alexander Reelsen Web development with the Play! framework June 2010 15 / 35

Core concepts Model
The Model class is a helper
Finders and Entity actions
// Query by property
User user = User.find("byUsername", username).first();
// Calls a setter
user.password = "foobar";
user.save();
List<User> users = User.findAll();
users.get(0).delete();
// JPA queries are possible as well, so are joins
List<String> names = User.find("select u.username from User u
order by u.username desc").fetch();
Alexander Reelsen Web development with the Play! framework June 2010 16 / 35

Core concepts Controller
Calling business logic
User controller
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);
}
...
Alexander Reelsen Web development with the Play! framework June 2010 17 / 35

Core concepts Controller
Calling business logic
User controller (ctd.)
...
public static void deleteUser(String username) {
User user = User.find("byUsername", username).first();
notFoundIfNull(user);
user.delete();
Application.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)
}
}
Alexander Reelsen Web development with the Play! framework June 2010 18 / 35

Core concepts Controller
Calling business logic
Example: Accessing the session
public class AuthController extends Controller {
@Before(unless = "login")
public static void checkSession() {
if (!request.session.contains("username")) {
forbidden("You are not authorized");
}
}
public void login(String username, String password) {
String pass = Crypto.passwordHash(password);
User user = User.find("byUsernameAndPassword",
username, pass).first();
notFoundIfNull(user);
request.session.put("username", user);
Application.index();
}
}
Alexander Reelsen Web development with the Play! framework June 2010 19 / 35

Core concepts View
The templating system
List users (app/views/Application/index.html)
#{ extends ’ main . html ’ /}
#{ set title : ’ Index ’ /}
< ul >
#{ list items : users , as : ’ user ’}
< li >
#{ a @Application . showUser ( user . username )}
$ { user . username }
#{/ a }
with email address $ { user . email }
</ li >
#{/ list }
</ ul >
Alexander Reelsen Web development with the Play! framework June 2010 20 / 35

Core concepts View
The templating system
Add user
#{ form @Application . createUser ()}
< div > Username :
< input type = " text " name = " user . username " / >
</ div >
< div > Password :
< input type = " pass " name = " user . password " / >
</ div >
< div > Email :
< input type = " text " name = " user . email " / >
</ div >
< input type = " submit " value = " Add user " / >
#{/ form }
Alexander Reelsen Web development with the Play! framework June 2010 21 / 35

Core concepts View
The templating system
More tags
doLayout, extends, include
if, ifnot, else, elseif
&{’i18nVariable’} out of conf/messages.de
Always access to: session, flash, request, params, lang,
messages, out, play
Alexander Reelsen Web development with the Play! framework June 2010 22 / 35

Core concepts View
The templating system
Extending objects using mixins
public class SqrtExtension extends JavaExtensions {
public static Double sqrt(Number number) {
return Math.sqrt(number.doubleValue());
}
}
The template code
< div >
Square root of x value is : $ { x . sqrt ()}
</ div >
Alexander Reelsen Web development with the Play! framework June 2010 23 / 35

Core concepts Testing
Testing
Providing test data
YAML formatted file provides testdata
User ( a l e r e e ) :
username : a l r
password : t e s t
email : a l e x a n d e r @ r e e l s e n . net
Loading test data...
@Before
public void setUp() {
Fixtures.deleteAll();
Fixtures.load("data.yml");
}
Alexander Reelsen Web development with the Play! framework June 2010 24 / 35

Core concepts Testing
Testing
Unit tests
Standard junit tests
Extend from UnitTest, which needs a JPA environment
Functional tests
Integration tests
Checks the external responses (http response)
Selenium tests
GUI tests
Very nice controllable, playback recorder
Possibility of doing step-by-step slow debugging
Alexander Reelsen Web development with the Play! framework June 2010 25 / 35

Core concepts Testing
Testing
CI with Calimoucho
Poor mans hudson
Checks out the project and runs play auto-test, which needs a
graphical layer for selenium tests
Check it under http://integration.playframework.org
Code coverage with cobertura
Enable the cobertura module in application.conf
Run the tests, check the results
Alexander Reelsen Web development with the Play! framework June 2010 26 / 35

Core concepts Jobs
Jobs - being asynchronous
Doing the right thing at the right time
Scheduled jobs (housekeeping)
Bootstrap jobs (initial data providing)
Suspendable requests (rendering a PDF report without blocking the
connection thread pool)
/* @Every("1h") */
@OnApplicationStart
public class LoadDataJob extends Job {
public void doJob() {
/* .. do whatever you want */
}
}
Alexander Reelsen Web development with the Play! framework June 2010 27 / 35

Core concepts Running Play in production
Putting play into production
The setup
A redirector like nginx or apache is preferred
Also eliminates the need to serve static files
Redirect to different nodes would be the main task
Profile per nodes possible (very useful for server farms)
Alexander Reelsen Web development with the Play! framework June 2010 28 / 35

Core concepts Running Play in production
Monitoring play application
Partial Output of play status
Monitors:
Application.showLatestRecipesRss(), ms. ->
4120 hits; 41.0 avg; 20.0 min; 260.0 max;
/app/views/Application/showLatestRecipesRss.html, ms. ->
4120 hits; 34.9 avg; 19.0 min; 235.0 max;
Datasource:
Job execution pool:
Scheduled jobs:
Alexander Reelsen Web development with the Play! framework June 2010 29 / 35

Ongoing development
Agenda
1 Introduction
Overview
2 Core concepts
Architecture
Conventions
Configuring routes
Model
Controller
View
Testing
Jobs
Running Play in production
3 Ongoing development
Features for Play 1.1
Module repository
Development forecast
Alexander Reelsen Web development with the Play! framework June 2010 30 / 35

Ongoing development Features for Play 1.1
Play 1.1 is on its way
Core features
Bug fixes
Scala support
More modules through module repository
Alexander Reelsen Web development with the Play! framework June 2010 31 / 35

Ongoing development Module repository
Useful modules
Slowly but steadily growing
Scala, Scalate, Akka
PDF, excel modules
Guice and Spring modules
Netty and grizzly support
GWT support, GAE support
Extended CSS, SASS
Ivy and Maven support
Siena, Ebean ORM, MongoDB
Database migration module
Hosting: stax, playapps
Alexander Reelsen Web development with the Play! framework June 2010 32 / 35

Ongoing development Development forecast
TODO
Open issues
NoSQL support (Siena, MongoDB)
Amazon Cloud Integration
Hosting platform (playapps.net has just launched)
Lucene Solr Support for shared environments
Tighter integration with JavaScript Toolkits like Dojo
Far more modules - check out the rich grails ecosystem
The first book... is coming!
Alexander Reelsen Web development with the Play! framework June 2010 33 / 35

Finish
Done!
Thanks for listening.
Questions?
Job offers regarding Java Scalability or new technologies like Play and/or
MongoDB?
Talk to me or send mail to alexander@reelsen.net
Alexander Reelsen Web development with the Play! framework June 2010 34 / 35

Finish
URLs
Further information
This presentation: http://www.slideshare.net/areelsen/
http://www.playframework.org
http://twitter.com/playframework
http://it-republik.de/jaxenter/artikel/
Webanwendungen-mit-dem-Java-Framework-Play!-2813.html
http://www.bookware.de/kaffeeklatsch/archiv/
KaffeeKlatsch-2009-11.pdf
http://www.bookware.de/kaffeeklatsch/archiv/
KaffeeKlatsch-2009-12.pdf
http://www.zenexity.fr/frameworks/
anatomie-dun-framework-de-developpement-web/
Alexander Reelsen Web development with the Play! framework June 2010 35 / 35