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Play framework 2.10 released (playframework.com)
183 points by emdagon on Feb 6, 2013 | hide | past | web | favorite | 73 comments

Release announcement - https://groups.google.com/forum/?fromgroups=#!topic/play-fra...

Major highlights of this release include:

* Migration to Scala 2.10

* Migration to Scala concurrent Futures

* Modularisation of Play itself

* Modularisation of routes files

* Better thread management and HTTP context propagation in Java projects

* Managed controller instantiation

* New Scala JSON API

* New Filter API with built in CSRF protection

* RequireJS support

* Content negotiation

* Improved Iteratee API

Migration to Scala 2.10

Looking forward to the new language features and performance improvements :)

and SSL: https://groups.google.com/d/msg/play-framework/FeTUDQwaEPg/q...

But not TLS (and client certificates, yet), that is for Play 2.2: https://github.com/playframework/Play20/pull/475

Since when is 10 < 2? (2.10 < 2.2)?

Edit: the title is wrong, it's play 2.1.0, not 2.10!!

yep, it can be easy to confuse that with scala 2.10

Does anyone know a good Django/Play comparison or Rails/Play comparison? Or a tutorial along the lines of "Play for Rails developers" or "Play for Django developers"?

I'm learning Scala and I want to play with it for webdev, but I know how much "hidden effort" is in learning any framework so i's really love something like this...

It borrows a lot of concepts from rails. I think that no "conversion" tutorial is needed, if you give it a shot it won't be long until you find yourself at home again.

I think it's true of Play 1.x but Play 2.x is a different animal. Yes Play 2.x overall is much better than Play 1.x. However Play 2.x threw out all of Play 1.x's developer convenience features that mirrored Rails. A good deal of Play 2.x is choose what you want. That's great for Play veterans, but not so much for new comers to both the Play, Scala, and Java ecosystem. Yes, you have to be somewhat familiar with all three sooner or later.

I'm also an Django developer and did a play application some time back[0], so maybe I can give some insight on development with Play!.

My background in functional program was non-existent at the time so going in I was already going to have problems. I choose to create my project as Scala project since I wanted to learn the tech. While Scala can be done with normal OOP/procedure programming I wanted to have the full affect of using Scala .

(These are my findings over the 2.0.x branches of Play! but should still be relevant to the current branch) Management:

Starting of a project is pretty simple, I have to say the Play! has done a great in baking in a good cli right into their framework and making it easy to plug in your own custom commands. I should mention that I was developing on a Windows 7 machine, in normal cases this wouldn't have been a problem but at the time with the 2.0.x version there were quite a few bugs with the project builder. For one, I couldn't use google closure compiler support due to some path finding issues "\" vs "/" and the stage, staged/start command didn't take windows into mind when generating the script. But for the most part these were small problems. It also has a less compiler ,which had a few problems causing me to patch my local ivy install, but should be all addressed now.

* Routing :

The routing files is located in conf/routes, which has a pretty simple DSL for defining your routes in a simple format :

<http_method> <path or regex> <method with option for defaults>

On thing that was lacking was the option to define multiple http methods for a route, meaning I could have a GET and POST route handled by the same function. While this may not be the best way to handle, but in some cases say with a /login route [1] it would be nice to have it all handled in one function or alteast defined once, but you have to declare both [2]

* Controllers:

Think of Play! controllers as Django class based views(cbv), the only difference is that Play! uses controllers are static, in all intent and purposes they still work the same and allow you to structure your code into sections of your site.

* Data Modeling:

Play! doesn't have an ORM/mapper per-say but they have a small jdbc wrapper that allows you to map your classes using Scala combinators syntax [3]. In a simple app this is easy to do, but you are still writing SQL and prone to errors. In my case I went with Squeryl [4], I tried to use ScalaQuery (which is now named Slick) but didn't like the api, maybe on my next project I'll revisit Slick since they have some nice features. By using Squerly I was able to get back the ORM mapping you would get with Django by first defining my Schema in code[5] (also provides sql create statements),Then I was able to easily map to Scala case classes, a win win here.

* Schema Migrations:

The default play doesn't have an eloquent way of managing schema changes, with Django you have South and it works fine most of the time. With play, you have a simple <revision>.sql setup stored in conf/evolutions/. Simply you tag your "up" and "down" schema changes and run a command in the cli to apply them.

* Templating:

The default Play! template system is pretty robust by its self, you can embed some scala code in it if needed. On thing about the template lang is that you must declare your templates with scala markup, so if you start a Play! project with Java you will still have to learn a bit of scala. Following with the how type safety of play and JVM technologies, the templates allow follow suite.This is good but sometimes you will run in a few problems when you want to pass a subset of data to templates, it took a while to realize that to access session information inside a template(again this maybe wasn't the best way to handle my problem) you had to declare an "implicit" value to gain an handle to the Request object. There are some other templates like one forked from Grovvy that are more advanced then the default system. But you can get pretty far by using the default templating engine.

* Request Handling:

Now this part I really liked, each request in Play! is handled by an "Action", and you are able to compose multiple actions together and come up with some nice implementations for say validating permissions. For instance, I needed to validate that a user had access to edit content for a giving dynamic domain and came up with a easy way[6] to just do

  def updateProfile = Authorize {
    implicit artist => implicit request =>

and have the associated artist and request all accessible without having to fetch the artist in my controller for example. You can also defer requests that may block so you can retain full non-blocking support throughout your codebase.

* Forms:

Play! has a great form api, its simple and pretty expressive [7] and provides validation, but I ran into the problem where I wanted to convert my posted data set into a Scala case class for instance or wanted to convert to a Double rather then an Integer. So I had to implement a "Binder" ,to implement this was actually simple then I thought after looking at the source. With a custom "Binder" I was able to say pass a string to the controller and its associated values and have it marshal to a Scala case class and then simplely invoke my method, its better to show by example then explain so check out the following [8][9]

So take you have a request like GET stats/metric&range=30days, rather then having to do the request parsing,database fetching in you controller you can create a binder and have it all done for you, so when it reaches the controller you are working with an data object rather then primitive values (Interger,Strings etc):

  def plays(range: Range) = TransAction {
    Authorize {
      implicit artist => implicit request =>
        Ok(g(Play ~ range))

As you see you pass a string value for "range" but since you are asking for an Range object, with the Binders Play! will convert in-between the two. The ~ syntax is just my sugar to quickly apply the range against the chosen metric (in this case the total Plays for an artist for the last 30days) and have it outputted back to the client all in json format (the "g" method is just a helper to convert the Scala case classes to json string output, I got tired of writing Json.forJson over and over). All the code that handles the actual querying is done by the "Play" metric providing an interface to apply the "Range" rules onto a predefined query, all type safety. I have to say I was pretty amazed and proud of myself for this setup alone, it made it really easy to build new metrics one I had the framework setup.

* Deploying :

Deploying on Django requires a few extra software to get everything going, you need a webserver and some workers (uwsgi,gunicorn etc). With Play! you just run "play start" into the cli and that’s it. There is a command to stage your changes that will execute its own start script. But unlike other Java web frameworks there is no need to have container (tomcat for example) in-front of your application, let along any webserver. This allows for quick development but in production you may want to add a web server or caching proxy in-front of it for best practices but its really isn't needed.

I could probably go into more detail (and may if others see any value) but Play! is a good framework for the Java/Scala community. Its not feature rich as say Django or Rails but with every problem or "Man I wish this was baked in" it wasn't that hard to do it my self, and this is from a guy that has never developed in Scala and Play! was my first introduction the Scala and the Play! framework as a whole.Ofcouse there were some "What were they thinking" moments and odd default configurations but you get that with anyframework I would guess. I did have lots of fun in the process and it made coding fun again, so I would definitely use Play! again, it seems now its more polished and some of the problems that I had have been addressed not the mention the new Json api is just beautiful.

[0]https://github.com/cideas/bulabowl [1]https://github.com/cideas/bulabowl/blob/master/app/controlle... [2]https://github.com/cideas/bulabowl/blob/master/conf/routes#L... [3]https://github.com/playframework/Play20/blob/master/samples/... [4]http://squeryl.org [5]https://github.com/cideas/bulabowl/blob/master/modules/commo... [6]https://github.com/cideas/bulabowl/blob/master/app/actions/A... [7]https://github.com/cideas/bulabowl/blob/master/app/models/Fo... [8]https://github.com/cideas/bulabowl/blob/master/app/binders/p... [9]https://github.com/cideas/bulabowl/blob/master/modules/commo... and https://github.com/cideas/bulabowl/blob/master/app/controlle...

You should make this a blog post and submit it.

Great writeup, but I have a comment on deploy: do you mean that "play start" can be used for production? Because otherwise, Django has runserver for development. It just shouldn't be used for production.

`play run` is sort of the equivalent of `runserver`. `play start` is one of the recommended[0] ways of running Play applications in production.

[0] http://www.playframework.com/documentation/2.1.0/Production

There is also `play dist` and `play stage`. They both wrap up all necessary assets / dependencies so that you don't even need play installed in order to start a play server (as the play framework jar gets bundled too). We use this for deploying rather than `play start`. The difference between dist and stage is that dist creates a single zip file in the target directory, whereas stage does not. Both create a file named 'start' in the target directory. The docs are not completely clear on that point.


You do not need "play" installed, as Play is using SBT as the package manager.

So without the framework installed and in your PATH, you can just go to an app's directory and do "sbt start". It will download all dependencies needed, compile your app and start the server.

Play's server is included in the framework and it is production ready.

kudos for the description and especially for the links, great for giving me a feeling of its "mindview"

Excellent writeup, thanks!

thanks a lot ! great write up,please make a blog post.

I'd say just jump in. The documentation are top notch. If you've used Rails it will feel very familiar to you. I'd say in an afternoon, if you have experience building web apps, you'll be up to speed.

I'd say most enterprise Java projects (think J2EE) have better documentation. I wouldn't choose Play because of that, I'd choose it because of the practicalities.

Congrats Play team! You really have a winning framework on your hands! Coming from a Java background, it was easy to learn; I was able to launch a dynamic MVP in three days on heroku (shameful plug): carsparkapp.com

It keeps getting better with each release, and as more plugins are written. The docs are really clear, and the community is thriving. Very good stuff!

When they say "predictable and minimal resource consumption (CPU, memory, threads)", what kind of numbers are we talking about, roughly?

They say they're using Akka to provide actors. And Akka seems... fast and small:


How fast and how small? How many K of memory?

This is an amazing effort by an amazing team. I have been using Play exclusively for two years now and each version keeps getting better and better

I have been using 2.10 RCs for couple of days (all non-blocking stuff), and I must say it's amazing! I am impressed.

Way to go guys! :)

IMO Play framework is the most important thing happening to Java right now.

I hope this brings Java back to everyday web development :)

It's all about the JVM these days, guess I should learn it.

Things are moving fast... I am still on 1.2.X for my applications as I fear the migration models, controllers and especially of Groovy templates to Scala templates.

Especially the increased compilation times when I hit reload are a turn of.

Yeah - Play 1.2.5 is still pretty awesome, too. It's still my go to (Java) platform for mocking up sites quickly, especially for APIs.

Play 2.1 seemed a bit slower to develop on. At least for me, it was definitely not as quick to get something up and running ASAP. Will need to check out 2.10 soon.

Love it. Exquisitely type safe. Just one thing: Weren't we supposed to get WAR deployment support in 2.1?

They haven't done this because the Servlet 3.1 spec has not been released yet. Play 2 supports some features that cannot be supported with Servlet containers <3.1 (probably stuff like web sockets). However, there is a 3rd party plugin that provides this functionality (as long as you avoid the unsupported features): https://github.com/dlecan/play2-war-plugin

I went through all RCs (from 1 to 4) with two applications. Happy to see release now. Great framework.

I've been eyeing Play for a bit now, but I've been wondering what kind of server it would require for a modest app with basic CMS functionality.

So, for example, will it run fine on a 128MB RAM VPS (assuming average IO speeds), a remote db and nginx?

As the other comment said, no need for NGinx unless you're dealing with external assets you don't want to add to your project structure.

That said, I will say I run my Blog on Play 2.1 (RC2 IIRC) and 512MB means I have to set some tuneables to limit the max memory to 384MB. I haven't figured out how to get those to work with 'play dist' either, so I got it running by cloning the source and installing Play locally. Which isn't much fun.

I'm sure with a little more digging I could figure it out. That said, the default limit of 1.5GB is probably there for a reason. It seems well suited to EC2's m1.small instance (1.7GB).

Considering the in-memory caching, I'd just pony up the $44/month for such an instance for anything more than my personal blog.

Play runs on Netty. No nginx needed.

I have Play! running on my Raspberry Pi with a total of 232 MB RAM and it runs fine, although it's a bit slow. Play! itself uses about 55 MB, so it might get a bit tight if you plan to run some other software too.

Play 2.1 = awesome, scala 2.10 = awesome, and loving the new website. This is a good time to be a web developer...

Mods, can you fix the title please? It's "2.1.0", not "2.10" (it runs on Scala 2.10, but the version is 2.1.0).

Why all those fancy effects of things flipping in your webpage?

It confused me for a while, until I understood it, then I think it is fancy, and useless.

But impressive maybe, if it was done using the tech they want you to use.

It's just a flashy thing to do nowadays in web dev, probably using jQuery Waypoints. I personally think it's quite cool, despite it's apparent uselessness.

Why did they decide to use static methods for the controllers?

Stated by Guillaume Bort here[1]

Play uses static methods only when it makes sense: - in the controller layer, because controllers are not object oriented. Controllers act as mapper between the HTTP world (that is stateless, and request/response based) and the Model layer that is fully object oriented.

[1]: http://stackoverflow.com/questions/5192904/play-framework-us...

It only 'makes sense' on a theoretical basis. On a practical basis, unit testing tons of static methods is a nightmare.

I find it pretty easy to test static methods. To me, testing a ton of static methods would seem a bit easier than testing a ton of classes, since static methods are usually stateless and so require less setup/cleanup work.

Could you explain a bit more about what makes static methods harder?

Static methods can be easy to test, if they are zero or near-zero dependency. e.g. Math.log(x) is easy to test.

However, a static method that accesses other layers is often very hard to test (at least in isolation). For example if you have a static controller method that accesses some service layer you would normally want to mock that service layer for testing so you can test the controller code in isolation.

If the method is non-static and that service layer object is a class member, it is very easy to replace your production service layer with a mock (using dependency injection or mockito, etc).

However if your controller is static, it can only access static members of its class or instantiate the service object with a 'new' operator. Either way there isn't a 'seam' in the code where something like dependency injection or mockito can intercept your app's wiring to replace the service object with a mocked version.

Worth noting I'm coming from the Java side of things here, perhaps Scala is built in such a way that 'new' and 'static' type things are interceptable in a way that allows mocking.

In our Play app, we isolate the real tricky stuff from our controllers and then write unit tests for it there. The controllers themselves end up being fairly lean and simple, so we test them (along with the front-end) with Selenium. We're not dogmatic about 100% coverage as we are a start-up trying to move fast, but this approach has worked well for us.

With Play 2.1 static controller methods are optional. If you prefix the controller reference in the routes file with @ then Play will instantiate the controller and call your instance method. It can instantiate it with Guice/Spring if you want as well.

Does this cause you any problems? Just curious - I'm using play, don't know the gotcha's... I just let it run free like an untamed beast.

This is awesome news. With this release Play has reached a level of maturity and elegance that will definitely make me consider it for my future projects.

Speaking strictly about the website redesign, I think that (although nice) it fails to communicate the framework biggest selling points. Some comments on that:

* The code-save-refresh workflow: this is mentioned briefly as "hit refresh workflow" which is confusing to say the least.

* Some other weird or 'meh' bullet points like type-safety (you're using either scala or java so you take that for granted) or stateless-web-tier.

* The introduction video is long. It's fine as a tutorial, but being the first thing you can click on I expect you to sell me the framework in 2-3 minutes or so (it can be done, play is fantastic).

Disclaimer: I love play and used it a lot last year. In fact I was part of the team that put the first play application into production on LinkedIn (featured in the bottom of the play site).

> * Some other weird or 'meh' bullet points like type-safety (you're using either scala or java so you take that for granted) or stateless-web-tier.

I think type-safety is mentioned because unlike Play 1.x, almost everything is type-safe in 2.x, such as templates and route definitions.

Anyone can write "stringly" typed code in Java or Scala.

new json api is bloody awesome! and when you add reactive mongo in the mix... oh my god

2.0.4 had bad defaults and documentation.

Some highlights:

- half baked config (no array. multiple values can be hacked as `foo.bar={a: 1, b: 1}`)

- can only set logging level in the config. and, xml logger config doesn't have application.conf values (logger.* in .conf are useless)

- routes dsl (meh)

- bad db connection pool. it kills all other connections if a connection fails, and goes into error state instead of re-connecting (it does reconnect for subsequent requests when pool is in error state)

the config has arrays, it is a json superset. foo.bar = [1, 1]

oh, i think i missed productIterator() in http://www.playframework.com/documentation/api/2.0.4/scala/i...

It could have been better if document had some examples: http://www.playframework.com/documentation/2.0.4/Configurati...

I can't even grep for productIterator on these projects: https://github.com/typesafehub/config/ https://github.com/playframework/Play20/

That probably means there's no test, example, poor documentation..

Actually, it's Product.productIterator, which is in scala api. I'm scala noob.


I've been looking for a way out of Rails. I dislike not having a compiler & analyser as I'm very comfortable with CLANG and LLVM.

Recently I've been looking at GoLang and Scala. Not sure which to go with, but Play seems better than most web frameworks for Go.

But my concern is always ecosystem. Now before you say "You have access to Java ecosystem" please take a look on how amazing the ruby eco system is.

I am planning to evaluate play! on some small projects.

Does anyone knows what are pros/cons using play with java/scala?

a question (not about the framework, but about the linked webpage) - this awesome effect where i scroll down and the pictures (next to the "Developer friendly" headline) "fold up", is there an animation-lib that does this? how is it called? it's awesome, i want it.

Ask @iamwarry on Twitter - Maxime Dantec did the site design. Talented fellow.

Looks very interesting. Good job.

Anyone use the play framework inside of IntelliJ IDEA? What's that experience like?

IntelliJ is the next best thing after sliced bread. You should definitely try it. It has great official support for Play.

The play 2 plugin is a disaster. It even breaks type-sensitive highlighting of regular scala files.

IDEA is otherwise fantastic though.

BTW, error in title, Not '2.10' but '2.1.0'

yup! Play 2.1.0 with Scala 2.10 :)

nothing that awesome to make me switch from Grails.

Is it easy to do non-blocking code in Grails? I have played with Groovy lately and it is definitely a productive language.

Is not as easy as using the Scala Future API or Akka Actors.

In Groovy you have to use Gpars (http://gpars.codehaus.org/), a third party library which is not as simple as Scala Futures, IMHO

Can you please elaborate?

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