Matt RaibleMatt Raible is a Web Architecture Consultant specializing in open source frameworks.

10+ YEARS


Over 10 years ago, I wrote my first blog post. Since then, I've authored books, had kids, traveled the world, found Trish and blogged about it all.

My HTML5 with Play Scala, CoffeeScript and Jade Presentation from Devoxx 2011

This week, I had the pleasure of traveling to one of my favorite places in the world: Antwerp, Belgium. Like last year, I traveled with the lovely Trish McGinity and spoke at Devoxx 2011. This year, my talk was on developing a web/mobile app with HTML5, Play, Scala, CoffeeScript and Jade. I was inspired to learn Scala at the beginning of this year and added CoffeeScript and Jade to my learning list after talking to James Strachan at TSSJS 2011. You can read more about how my journey began in my first post about learning these technologies.

I started developing with these technologies in August and wrote about my learnings throughout the process. Last week, while writing my presentation, I decided it'd be fun to make my presentation into more of a story-telling-session than a learn-about-new-technologies session. To do this, I focused on talking a bit about the technologies, but more about my experience learning them. I also came up with a challenging idea: create a video that showed the development process, how hard it was to test the app and (hopefully) my success in getting it to work.

It was all a very close call, but I'm happy to say I pulled it off! I got the app to work on an iPhone (thanks to PhoneGap) last Saturday, finished the first draft of my presentation on Sunday night (after pulling an all-nighter) and finished editing the demo video on Wednesday night. My talk was on Thursday afternoon and I had a blast talking about my experience to such a large, enthusiastic audience. You can see the presentation below, on Slideshare or download the PDF.

You can find the "demo" for this talk on YouTube or watch it below.

One of the reasons I really enjoyed this talk is it only represents one milestone in my learning process. I plan on continuing to develop this application and learning more about HTML5, Scala, Play and CoffeeScript and Scalate/Jade. Now that Play 2.0 Beta has been released, I plan on upgrading to it and leveraging its native CoffeeScript and LESS support. I hope to continue using Scalate and its Jade format. And it's very likely PhoneGap will continue to be the bridge that allows everything to run in the background.

I've been talking with the Jfokus folks about doing this talk in Sweden in Feburary and Devoxx France about presenting there in April.

Learning all these technologies has been a challenging, but fun experience so far. As the last slide in my presentation says, I encourage you to do something similar. Pick something new to learn, have fun doing it, but more importantly - get out there and Play!

Update Dec. 20th: A video of this presentation is now available on Parleys.com.

Posted in Java at Nov 18 2011, 11:18:38 AM MST 6 Comments

Deploying Java and Play Framework Apps to the Cloud with James Ward

Yesterday, I attended James Ward's presentation on Deploying Java & Play Framework Apps to the Cloud at Devoxx. I arrived a bit late, but still managed to get there in time to see a lot of demos and learn more about Heroku. Below are my notes from James's talk.

When I arrived, James was doing a demo using Spring Roo. He was using Roo's Petclinic sample app and showed us how you could use Git to create a local repository of the new project and install Heroku's command line tool. From there, he ran the following command to create a new application on Heroku.

heroku create -s cedar

The Cedar Stack is what supports Java, Scala and Play Framework. It's the 3rd generation stack for Heroku. The command above created two endpoints, one for HTTP and one for Git. It picks from a list of randomly generated names, which all seem to have some humor in them. James ended up with "electric-sword-8877" for this demo.

From there, he ran git push heroku master to deploy the project to Heroku. Unfortunately, this resulted in a login error and there was an akward moment where we all thought the Demo Gods were angry. However, James was able to resolve this by using Heroku's sharing feature with the following command.

heroku sharing:add jw@heroku.com

For Java projects, Heroku looks for a pom.xml file in the root directory and runs a Maven build on project. All the dependencies get downloaded on the cloud rather than put them into a WAR and requiring you to upload a large WAR file. You don't have to upload your source code to Heroku; James did it for the sake of the demo because it was faster.

After the build finishes, it creates a slug file. This file contains everything Heroku needs to run your application.

Next, James showed a demo of the running application and added a new Pet through its UI. Then he scaled it to two servers using the following command:

heroku scale web=2

He proved this was working by running heroku ps, which showed there were two running processes. He showed the app again, but noted that the record he added was missing. This is because when it started up a new dyno, Hibernate created the schema again and deleted all records. To fix, James changed Hibernate to only update the schema instead of create a new one. If you're a Hibernate user, you know this is as simple as changing:

hibernate.hbm2ddl.auto=create

to:

hibernate.hbm2ddl.auto=update

After committing this change, James redeployed using Git.

git push heroku master

The slug file got built again and Heroku deployed the new slug onto both dynos, automatically load balancing the app across two servers. James then ran heroku logs to see the logs of his dynos and prove that a request to his app's HTTP endpoint made requests to both dynos. The logging is powered by Logplex and you can read about how it works in the article Heroku Gets Sweet Logging.

James mentioned that Roo has a Heroku plugin, but after watching his talk and searching a bit on the internet, it seems it's just the jetty-runner setup as described in Getting Started with Spring MVC Hibernate on Heroku/Cedar.

What about autoscaling? There are some 3rd party tools that do this. Heroku's Management infrastructure has APIs that these tools talk too. Heroku hasn't built autoscaling into the platform because they don't know where the bottlenecks are in your application.

Heroku = Polyglot + PaaS + Cloud Components. It supports Ruby, node.js, Java, Clojure, Play and Scala and they're working on native Grails and Gradle support. There's currently 534,374 apps running on Heroku.

Heroku is a cloud application platform and there's 5 different components.

  1. Instant deployment
  2. HTTP Routing / Load Balancing
  3. Elastic Polyglot Runtime
  4. Management & Logging
  5. Component as a Service Ecosystem

For instant deployment, it's a pretty simple process:

  • You add files to a git repo
  • You provision the app on Heroku (heroku create)
  • You upload the files to Heroku (git push heroku master)
  • Heroku runs the build and assembles a "slug" file
  • Heroku starts a "dyno"
  • Heroku copies the "slug" to the "dyno"
  • Heroku starts the web application

Most apps will contain a Procfile that contains information about how to run the web process. For Spring Roo, it has:

web: java $JAVA_OPTS -jar target/dependency/jetty-runner.jar --port $PORT target/*.war

So how does Heroku decide what application server to use? It doesn't, you do. You need to get your application server into the slug file. The easiest way to do this is to specify your application server as a dependency in your pom.xml. In the Roo example, James uses the maven-dependency-plugin to get the jetty-runner dependency and copy it to the target directory. On Heroku, you bring your application server with you.

Heroku gives you 750 free dyno hours per app, per month. For developers, it's very easy to get started and use. Once you extend past one dyno, it's $.05 per dyno hour, which works out to around $30/month. It's only when you want to scale beyond one dyno where you get charged by Heroku, no matter how much data you transfer. Scalatest is running on Heroku. It has one dyno and is doing fine with that. Bill Venners doesn't have to pay anything for it.

java.herokuapp.com is a site James created that allows you to clone example apps and get started quickly with Heroku's Cedar Stack.

For HTTP Routing, Heroku uses an Erlang-based routing system to route all the HTTP requests across your dynos. Heroku doesn't support sticky sessions. Distributed session management does not work well, because it does not scale well. Heroku recommends you use a stateless web architecture or move your state into something like memcached. Jetty has (in the latest version) the ability to automatically serialize your session into a Mongo system. This works fine on Heroku. The problem with this is if you have 2 dynos running, each request can hit a different dyno and get different session state. Hence the recommendation for an external storage mechanism that can synchronize between dynos.

You can also run non-web applications on Heroku. You can have one web process, but as many non-web processes as you want.

Heroku has native support for the Play framework. To detect Play applications, it look for a conf/application.conf file. You don't need to have a Procfile in your root directory because Heroku knows how to start a Play application.

At this point, James created a new Play application, created a new Heroku app (he got "young-night-7104" this time) and pushed it to Heroku. He created a simple model object, a controller to allow adding new data and then wrote some jQuery to show new records via Ajax and JSON. He also showed how to configure the application to talk to Heroku's PostgreSQL database using the DATABASE_URL environment variable. He explained how you can use the heroku config command to see your environment variables.

The reason they use environment variables is so Heroku can update DATABASE_URL (and other variables) without having to call up all their customers and have them change them in their source code.

Play on Heroku supports Scala if you create your app with Scala. Play 2.0 uses Scala, Akka and SBT. Heroku added support for SBT a couple month ago, so everything will work just fine.

Heroku also supports Scala, detecting it by looking for the build.sbt file in the root directory. Heroku supports SBT 0.11.0 and it builds the 'stage' task. It currently does not support Lift because Lift uses an older version of SBT and because it's a very stateful framework that would require sticky sessions. Use Play, BlueEyes or Scalatra if you want Scala on Heroku.

Heroku has addons for adding functionality to your application, including Custom DNS, HTTPS, Amazon RDS, NoSQL and many more. They're also working on making their add-on and management APIs available via Java, so you'll (hopefully) be able to use them from your IDE in the future.

From there, James showed us how Heroku keeps slug files around so you can do rollbacks with heroku rollback. He also showed how you can use:

heroku run "your bash command"
to run any Bash command on the cloud.

Summary
I attended James's talk because he's a good friend, but also because I've been using Heroku to host my latest adventures with Play, Scala, CoffeeScript and Jade. I'm glad I attended because I learned some good tips and tricks and more about how Heroku works.

Heroku seems like a great development tool to me. In my experience, it's been really nice to have instant deployments using Git. In fact, I've created a 'push' alias so I can push to my project's repo and heroku at the same time.

alias push='git push origin master && git push heroku master'

I'd like to see more organizations embrace something like Heroku for developers. It'd be great if everyone had their own sandbox that business owners and product managers could see. I can't help but think this would be awesome for demos, prototyping, etc.

There were some other talks I wanted to attend at the same time, particularly Martin Odersky's What's in store for Scala? and WWW: World Wide Wait? A Performance Comparison of Java Web Frameworks. The WWW talk has posted their presentation but I'm sure it'd be more fun to watch.

It's pretty awesome that all the talks from Devoxx 2011 will be up on Parleys.com soon.

Update: James has posted his slides from this talk.

Posted in Java at Nov 18 2011, 08:14:45 AM MST 2 Comments

PhoneGap for Hybrid App Development

This afternoon, I attended Brian LeRoux's talk on PhoneGap for Hybrid App Development at Devoxx. You might remember that I tried PhoneGap last week and really enjoyed my experience. Below are my notes from Brian's talk.

PhoneGap is a project for creating native applications using HTML, CSS and JavaScript. PhoneGap started out as a hack. In 2007, Apple shipped the iPhone and Steve Jobs told everyone they should develop webapps. PhoneGap started in 2008 as a lofty summertime hack and gained traction as a concept at Nitobi with Android and Blackberry implementations in the fall. In 2009, people started to pay attention when PhoneGap got rejected by Apple. They added Symbian and webOS support and Sony Ericsson started contributing to the project. They got rejected because all PhoneGap-developed apps were named "PhoneGap". This turned out to be good press for the project and Apple let them in shortly after.

In 2010, IBM began tag-teaming with Nitobi and added 5 developers to the project after meeting them at OSCON. In 2011, RIM started contributing as well as Microsoft. Then Adobe bought the company, so they're obviously contributing.

PhoneGaps Goals: the web is a first class platform, so let people create installable web apps. Their second goal is to cease to exist and get browsers to adopt their model.

PhoneGap is NOT a runtime or a compiler/transpiler. It's not an IDE or predefined framework or proprietary lockin. It's Apache, MIT and BSD licensed to guarantee it's as free as free software gets. You can do whatever you want to do with it. PhoneGap has recently been contributed to the Apache Software Foundation.

As far as Adobe vs. PhoneGap is concerned, the Nitobi team remains contributors to PhoneGap. Adobe is a software tools company and has Apache and WebKit contributors. PhoneGap/Build integration will be added to Creative Cloud.

The biggest issues with contributing PhoneGap to Apache is renaming the project and source control. I'm not sure why it needs to be renamed, but it's likely that Apache Callback is out. There seems to be some consensus on Apache Cordova. Apache likes SVN and the PhoneGap community currently uses Git. They're trying to find a medium road there, but would prefer to stay on Git.

The PhoneGap technique is colloquially called "the bridge". It's a 3 step process: they instantiate a WebView, then they call JavaScript from native code, then they call native code from JavaScript. Apparently, all device APIs are available via JavaScript in a WebView.

The primary platforms supported are iOS >= 3, Android >= 1.5 and BlackBerry >= 5.x. They also support webOS, Symbian, Samsung Bada and Windows Phone. No mobile dev platform supports as many deploy targets as PhoneGap. Primary contributors are Adobe, IBM, RIM and Microsoft.

Documentation for PhoneGap is available at http://docs.phonegap.com. Device APIs for PhoneGap 1.0 included sensors, data and outputs, which all devices have. Examples of sensors are geolocation and camera. Data examples are the filesystem, contacts and media. Outputs are screens, speakers and the speaker jack. All PhoneGap APIs are plugins, but any native API is permitted.

What about security? Brian recommends looking at the HTML5 Security Cheatsheet. PhoneGap has added a lot of security measures since they've found the native API pretty much opens up everything.

PhoneGap doesn't bundle a UI framework, but they support any JavaScript framework that works in the browser. PhoneGap is just a fancy browser, so your code run in less fancy web browsers too. This means you can develop and test your app in your desktop browser and only use PhoneGap to package and distribute your app.

Competition? PhoneGap has no competition.

PhoneGap/Build is for compiling your apps in the cloud and free for open source projects. The biggest reason they did this is because they couldn't redistribute all the SDKs and it was a pain for developers to download and install SDKs in training classes.

For mobile app development, you should have a singular goal. Do one thing really well if you want to be successful. Great UX happens iteratively. You know that the web works and has been widely successfully cross-platform. It's likely you've already invested in the web. Start by building a mobile web client and use PhoneGap as a progressive enhancement technique.

Shipping and unit testing should be a daily activity. Automate everything so you can have one-click builds (test/dev/release). For web client design, constraints are your ally in the battle against complexity and "clients who are not chill". Phones suck and consume a lot: cpu, ram, bandwidth, battery, network... everything! Start with a benchmark of app performance and monitor that benchmark. If you have tons and tons of features, consider splitting into multiple apps.

The mobile web is not WebKit! Opera is huge, Firefox is making strides and IE still happens. For layouts: use flex-box rules (anyone got a link to these?), css media queries and meta tags for viewport. You should try to develop your app without frameworks because they come with a ton of code and can effect the size of your app.

Looks can kill: aesthetics that can hurt performance: border-radius, box-shadow and gradients can slow down your apps. Chances are, you really don't need these features. Design your app for your brand, not for the device manufacturer. An app that looks like an iPhone app on Android doesn't give a positive impression.

For JavaScript libraries, start with your problem, not a generic solution like Sencha or jQuery Mobile. Zepto and its older brother XUI are all you need to start. Jo is a fantastic option. Backbone and Spine are worth watching.

For testing, QUnit and Jasmine are pretty popular. For deployment, concat, minify and obfuscate your JavaScript and CSS. Or you can inline everything into the markup to minimize HTTP chatter. Gmail inlines and comments all their JavaScript and then evals it.

From there, Brian recommended leveraging HTML5's AppCache and and using RESTful JSON endpoints for legacy systems. Next, he tried to show us a demo of a photo sharing application. Unfortunately, the Demo Gods were grumpy and Brian couldn't get his computer to recognize his Android phone. He did show us the client code and it's pretty impressive you can use 1 line of code to take a picture on a phone.

The last thing we looked at was debug.phonegap.com. This is an app that's powered by weinre. It lets you enter a line of JavaScript in your client and then remotely debug it in a tool that looks like Chrome's Web Inspector. Very cool stuff if you ask me.

Summary
I really enjoyed learning more about PhoneGap, particularly because Brain emphasized all my web development skills can be used. I don't have to learn Objective-C or Android to develop native apps and I don't even have to install an SDK if I use PhoneGap/Build. Of course, my mobile developer friends might disagree with this approach. In the meantime, I look forward to using PhoneGap to turn my mobile web clients into native apps and finding out if it's really as good as they say it is.

Posted in The Web at Nov 16 2011, 10:22:16 AM MST 2 Comments

Play 2.0, A web framework for a new era

This week, I'm in Antwerp, Belgium for the annual Devoxx conference. After traveling 21 hours door-to-door yesterday, I woke up and came to the conference to attend some talks on Play and PhoneGap. I just got out of the session on Play 2.0, which was presented by Sadek Drobi and Guillaume Bort. Below are my notes from this presentation.

The Play 2.0 beta is out! You can read more about this release on the mailing list. This beta includes native support for both Scala and Java, meaning you can use both in the same project. The release also bundles Akka and SBT by default.

In other news, Play 2.0 is now part of the Typesafe Stack. Typesafe is the Scala company, started by the founder of Scala (Martin Odersky) and the founder of Akka (Jonas Bonér). Guillaume is also joining the Typesafe Advisory Board.

Sadek and Guillaume both work at zenexity, where Play is the secret weapon for the web applications they've built for the last decade. Play was born in the real world. They kept listening to the market to see what they should add to the project. At some point, they realized they couldn't keep adding to the old model and they needed to create something new.

The web has evolved from static pages to dynamic pages (ASP, PHP). From there, we moved to structured web applications with frameworks and MVC. Then the web moved to Ajax and long-polling to more real-time, live features. And this changes everything.

Now we need to adapt our tools. We need to handle tremendous flows of data. Need to improve expressiveness for concurrent code. We need to pick the appropriate datastore for the problem (not only SQL). We need to integrate with rapidly-evolving client side technologies like JavaScript, CoffeeScript, and Dart. We need to use elastic deployment that allows scaling up and scaling down.

zenexity wanted to integrated all of these modern web needs into Play 2.0. But they also wanted to keep Play approachable. They wanted to maintain fast turnaround so you can change your code and hit reload to see the changes. They wanted to keep it as a full stack framework with support for JSON, XML, Web Services, Jobs, etc. And they wanted to continue to use and conventions over configuration.

At this point, Guillaume did a Play 2.0 Beta demo, show us how it uses SBT and has a console so everything so it runs really fast. You can have both Scala and Java files in the same project. Play 2.0 templates are based on Scala, but you don't need to know Scala to use them. You might have to learn how to write a for loop in Scala, but it's just a subset of Scala for templates and views. SBT is used for the build system, but you don't have to learn or know SBT. All the old play commands still work, they're just powered by a different system.

After the demo, Sadek took over and started discussing the key features of Play 2.0.

To handle tremendous amounts of data, you need to do chunking of data and be able to process a stream of data, not just wait until it's finished. Java's InputStream is outdated and too low level. Its read() method reads the next byte of data from the input and this method can block until input data is available.

To solve this, Play includes a reactive programming feature, which they borrowed from Haskell. It uses Iteratee/Enumerator IO and leverages inversion of control (not like dependency injection, but more like not micro-managing). The feature allows you to have control when you need it so you don't have to wait for the input stream to complete. The Enumerator is the component that sends data and the Iteratee is the component that receives data. The Iteratee does incremental processing and can tell the Enumerator when it's done. The Iteratee can also send back a continuation, where it tells the Enumerator it wants more data and how to give it. With this paradigm, you can do a lot of cool stuff without consuming resources and blocking data flow.

Akka is an actor system that is a great model for doing concurrent code. An Actor could be both an Enumerator and an Iteratee. This vastly improves the expressiveness for concurrent code. For example, here's how you'd use Akka in Play:

def search(keyword: String) = Action {
  AsyncResult {
    // do something with result
  }
}

Play does not try to abstract data access because datastores are different now. You don't want to think of everything as objects if you're using something like MongoDB or navigating a Social Graph. Play 2.0 will provide some default modules for the different datastores, but they also expect a lot of contributed modules. Anorm will be the default SQL implementation for Play Scala and Ebean will be the default ORM implementation for Play Java. The reason they've moved away from Hibernate is because they needed something that was more stateless.

On the client side, there's so many technologies (LESS, CoffeeScript, DART, Backbone.js, jQuery, SASS), they didn't want to bundle any because they move too fast. Instead, there's plugins you can add that help you leverage these technologies. There's a lot of richness you can take advantage of on the client side and you need to have the tools for that.

Lastly, there's a new type of deployment: container-less deployment to the cloud. Akka allows you to distribute your jobs across many servers and Heroku is an implementation of elastic deployment that has built-in support for Play.

They've explained what they tried to design and the results of this new, clean architecture have been suprising. Side effects include: type-safety everywhere for rock-solid applications. There's an awesome performance boost from Scala. There's easier integration with existing projects via SBT. And it only takes 10 lines of code to develop an HTTP Server that responds to web requests.

The memory consumption is amazing: only 2MB of heap is used when a Play 2.0 app is started. Tests on Guillaume's laptop have shown that it can handle up to 40,000 requests per second, without any optimization of the JVM. Not only that, but after the requests subside, garbage collection cleans up everything and reduces the memory consumption back to 2MB.

At this point, Guillaume did another demo, showing how everything is type-safe in 2.0, including the routes file. If you mistype (or comment one out) any routes, the compiler will find it and notify you. Play 2.0 also contains a compiled assets feature. This allows you to use Google's Closure Compiler, CoffeeScript and LESS. If you put your LESS files in app/assets/stylesheets, compilation errors will show up in your browser. If you put JavaScript files in app/assets/javascripts, the Closure compiler will be used and compilation errors will show up in your browser.

Play 2.0 ships with 3 different sample applications, all implemented in both Java and Scala. HelloWorld is more than just text in a browser, it includes a form that shows how validation works. Another app is computer-database. When Guillaume started it, we saw how evolutions were used to create the database schema from the browser. The Play Team has done their best to make the development process a browser-based experience rather than having to look in your console. The computer-database is a nice example of how to do CRUD and leverages Twitter's Bootstrap for its look and feel.

The last sample application is zentasks. It uses Ajax and implements security so you can see how to create a login form. It uses LESS for CSS and CoffeeScript and contains features like in-place editing. If you'd like to see any of these applications in action, you can stop by the Typesafe booth this week at Devoxx.

Unfortunately, there will be no migrating path for Play 1.x applications. The API seems very similar, but there are subtle changes that make this difficult. The biggest thing is how templating has changed from Groovy to Scala. To migrate from 1.2.x would be mostly a copy/paste, modify process. There are folks working on getting Groovy templates working in 2.0. The good news is zenexity has hundreds of 1.x applications in production, so 1.x will likely be maintained for many years.

Summary
This was a great talk on what's new in Play 2.0. I especially like the native support for LESS and CoffeeScript and the emphasis on trying to keep developers using two tools: their editor and the browser. The sample apps look great, but the documentation look sparse. I doubt I'll get a chance to migrate my Play 1.2.3 app to 2.0 this month, but I hope to try migrating sometime before the end of the year.

Posted in Java at Nov 16 2011, 05:58:09 AM MST 11 Comments

PhoneGap to the Rescue!

This is the 7th article in a series about my adventures developing a web application with HTML5, Play Scala, CoffeeScript and Jade. Previous articles can be found at:

  1. Integrating Scalate and Jade with Play 1.2.3
  2. Trying to make CoffeeScript work with Scalate and Play
  3. Integrating HTML5 Boilerplate with Scalate and Play
  4. Developing with HTML5, CoffeeScript and Twitter's Bootstrap
  5. Play Scala's Anorm, Heroku and PostgreSQL Issues
  6. More Scalate Goodness for Play
A few weeks ago, I wrote about Developing a Stopwatch and Trip Meter with HTML5. I mentioned I'd run into a major issue when I discovered HTML5 Geo's watchPosition() feature didn't run in the background. From that article:

I tried out the trip meter that evening on a bike ride and noticed it said I'd traveled 3 miles when I'd really gone 6. I quickly figured out it was only calculating start point to end point and not taking into account all the turns in between. To view what was happening, I integrated my odometer.coffee with my map using Google Maps Polylines. Upon finishing the integration, I discovered two things, 1) HTML5 geolocation was highly inaccurate and 2) geolocation doesn't run in the background.

At the time, I opted to ignore this issue and use my app by setting Auto-Lock to Never. This worked, but if I happened to bump my phone while exercising, the app would get closed. Not to mention it really drained the battery and seemed to crash every-so-often.

Last week, I realized things were getting down to the wire and I was running out of time to finish my app's functionality for my Devoxx Talk. On Wednesday afternoon, I asked my office-mates (2 iOS developers) about developing a native app and installing it on my phone. They told me I had to be a iOS Certified Developer ($99/year) or jailbreak my iPhone to get an app on it. On Thursday, I downloaded PhoneGap and installed Xcode 4. As you can tell from the following image, PhoneGap seemed to be exactly what I was looking for.

PhoneGap

I spent some time going through PhoneGap's Getting Started Guide and was able to get my app rendering in a short amount of time. I was able to copy the webapp's generated HTML into my PhoneGap project's www directory and launch the app in the iOS Simulator. The only change I had to make was to convert my inline CoffeeScript (that used coffee-script.js for in-browser compilation) to JavaScript. It's possible the in-browser compiler works, but when things didn't work and I didn't see any error messages, it was the first thing I changed.

For getting the app onto a phone for testing, I opted for the easiest route and applied for an iOS Developer Account on Thursday afternoon. While waiting for approval on Friday, I briefly tried to jailbreak my phone, but encountered all kinds of version issues and gave up after 30 minutes. 24 hours after I applied for my account, Apple emailed asking for a business document to prove I was legit. I was unable to download any from the Colorado Secretary of State that were e-certified, so expeditiously switched my application from a business account to an individual one. Apple was great in helping me out before the weekend started and I had everything I needed as we drove to our Ski Shack on Friday evening.

On Friday night, I upgraded Trish's iPhone 4 to iOS 5 to make sure I had the latest and greatest platform for my app. Saturday morning, I woke up around 8 and started trying to figure out how to get my app on her phone. It took about an hour of fumbling, grumbling and searching to figure out how to do this. All the while, the troops were getting restless, noting that they were hungry for breakfast and groaning about Daddy taking so long. At 9:30, I finally got my PhoneGap app installed on Trish's phone and we drove to breakfast at Sharkey's.

I started the app when we left and checked it 5 minutes later when we arrived for breakfast. The blood drained from my face when I saw the app had drawn a straight line from our condo to the breakfast joint. We had taken several turns along the way and my new native app ignored them all. I assumed I had failed and my talk's conclusion at Devoxx would be "You can't develop a reliable Fitness Tracker app with HTML5". However, after a delicious Eggs Benedict, I became determined to succeed and returned home for some more hacking.

This is when I discovered Joel Dare's Play an MP3 Audio Stream in PhoneGap tutorial and the "Required background modes" key. This was the knowledge that saved the day and I anxiously added the key and the values to get location updates and allow audio to run in the background.

Required Background Modes

Saturday afternoon, I strapped on my recently purchased GoPro Camera, shot some video for my demo at Devoxx and had a blast skiing with Abbie, Jack and Trish. I celebrated that evening with an executive workout (15 minutes each in hot tub, sauna and steam room) at the Fraser Rec Center and again on Sunday when the Broncos whooped the Kansas City Chiefs just like last year.

Last night, I stayed up late to put the finishing touches on my Devoxx presentation. Now I'm sitting at the Red Carpet Club in Chicago's O'Hare getting ready to depart for Belgium. It's been a fun journey learning about HTML5, Scala, Play, CoffeeScript and Jade. If you're at Devoxx this week, I think I've got a presentation you're really going to like. ;-)

Posted in Java at Nov 14 2011, 04:32:19 PM MST 2 Comments

More Scalate Goodness for Play

Scalate This article is the 6th in a series on about my adventures developing a web application with HTML5, Play Scala, CoffeeScript and Jade. Previous articles can be found at:

  1. Integrating Scalate and Jade with Play 1.2.3
  2. Trying to make CoffeeScript work with Scalate and Play
  3. Integrating HTML5 Boilerplate with Scalate and Play
  4. Developing with HTML5, CoffeeScript and Twitter's Bootstrap
  5. Play Scala's Anorm, Heroku and PostgreSQL Issues

Last week, I wrote about my adventures with Anorm and mentioned I'd made some improvements to Scalate Play interoperability. First of all, I've been using a Scalate trait and ScalateTemplate class to render Jade templates in my application. I described this setup in my first article on Scalate and Play.

Adding SiteMesh Features and Default Variables
When I started making my app look good with CSS, I started longing for a feature I've used in SiteMesh. That is, to have a body id or class that can identify the page and allow per-page CSS rules. To do this with SiteMesh, you'd have something like the following in your page:

  
<body id="signup"/>

And then read it in your decorator:

<body<decorator:getProperty property="body.class" writeEntireProperty="true"/>>

As I started looking into how to do this, I came across Play Scala's ScalaController and how it was populating Play's default variables (request, response, flash, params, etc.). Based on this newfound knowledge, I added a populateRenderArgs() method to set all the default variables and my desired bodyClass variable.

def populateRenderArgs(args: (Symbol, Any)*): Map[String, Any] = {
  val renderArgs = Scope.RenderArgs.current();

  args.foreach {
    o =>
      renderArgs.put(o._1.name, o._2)
  }

  renderArgs.put("session", Scope.Session.current())
  renderArgs.put("request", Http.Request.current())
  renderArgs.put("flash", Scope.Flash.current())
  renderArgs.put("params", Scope.Params.current())
  renderArgs.put("errors", validationErrors)
  renderArgs.put("config", Play.configuration)

  // CSS class to add to body
  renderArgs.put("bodyClass", Http.Request.current().action.replace(".", " ").toLowerCase)
  renderArgs.data.toMap
}

implicit def validationErrors:Map[String,play.data.validation.Error] = {
  import scala.collection.JavaConverters._
  Map.empty[String,play.data.validation.Error] ++ 
    Validation.errors.asScala.map( e => (e.getKey, e) )
}

After adding this method, I was able to access these values in my templates by defining them at the top:

-@ val bodyClass: String 
-@ val params: play.mvc.Scope.Params
-@ val flash: play.mvc.Scope.Flash

And then reading their values in my template:

body(class=bodyClass)
...
- if (flash.get("success") != null) {
  div(class="alert-message success" data-alert="alert")
    a(class="close" href="#") &×
    | #{flash.get("success")}
- }
...
  fieldset
    legend Leave a comment →
    div.clearfix
      label(for="author") Your name:
      input(type="text" name="author" class="xlarge" value={params.get("author")})
    div.clearfix
      label(for="content") Your message:
      textarea(name="content" class="xlarge") #{params.get("content")}
    div.actions
      button(type="submit" class="btn primary") Submit your comment
      button(type="reset" class="btn") Cancel

For a request like Home/index, the body tag is now rendered as:

<body class="home index">
This allows you to group CSS styles by Controller names as well as by method names.

Next, I started developing forms and validation logic. I quickly discovered I needed an action() method like the one defined in ScalaTemplate's TemplateMagic class.

def action(action: => Any) = {
  new play.mvc.results.ScalaAction(action).actionDefinition.url
}

Since TemplateMagic is an inner class, I determined that copying the method into my ScalateTemplate class was the easiest workaround. After doing this, I was able to import the method and use it in my templates.

-import controllers.ScalateTemplate._
...
form(method="post" class="form-stacked" id="commentForm"
     action={action(controllers.Profile.postComment(workout._1.id()))})

After getting the proper URL written into my form's action attribute, I encountered a new problem. The Play Scala Tutorial explains validation flow as follows:

if (Validation.hasErrors) {
  show(postId)
} else {
  Comment.create(Comment(postId, author, content))
  Action(show(postId))
}

However, when I had validation errors, I end up with the following error:

Could not load resource: [Timeline/postComment.jade]

To fix this, I added logic to my Scalate trait that looks for a "template" variable before using Http.Request.current().action.replace(".", "/") for the name. After making this change, I was able to use the following code to display validation errors.

if (Validation.hasErrors) {
  renderArgs.put("template", "Timeline/show")
  show(postId)
} else {
  Comment.create(Comment(postId, author, content))
  Action(show(postId))
}

Next, I wanted to give child pages the ability to set content in parent pages. With SiteMesh, I could use the <content> tag as follows:

<content tag="underground">
  HTML goes here
</content>

This HTML could then be retrieved in the decorator using the <decorator:getProperty> tag:

<decorator:getProperty property="page.underground"/>

With Scalate, I found it equally easy using the captureAttribute() method. For example, here's how I captured a list of an athlete's workouts for display in a sidebar.

- captureAttribute("sidebar")
  - Option(older).filterNot(_.isEmpty).map { workouts =>
    .older-workouts
      h3
        | Older workouts
        span.from from this app
      - workouts.map { workout =>
        - render("workout.jade", Map('workout -> workout, 'mode -> "teaser"))
      - }
  - }
- }

Then in my layout, I was able to retrieve this and display it. Below is a snippet from the layout I'm using (copied from Twitter's Bootstrap example). You can see how the sidebar is included in the .span4 at the end.

-@ val sidebar: String = ""
...
.container
  .content
    .page-header
      h1
        = pageHeader
        small
          = pageTagline
    .row
      .span10
        !~~ body
      .span4
        = unescape(sidebar)
  footer

View vs. Render in Scalate
In the sidebar code above, you might notice the render() call. This is the Scalate version of server-side includes. It works well, but there's also a view() shortcut you can use if you want to have templates for rendering your model objects. I quickly discovered it might be difficult to use this feature in my app because my object was Option[(models.Workout, models.Athlete, Seq[models.Comment])] instead of a simple object. You can read the view vs. render thread on the Scalate Google Group if you're interested in learning more.

Scalate as a Module
The last enhancement I attempted to make was to put Scalate support into a Play module. At first, I tried overriding Play's Template class but ran into compilation issues. Then Guillaume Bort (Play's lead developer) recommended I stick with the trait approach and I was able to get everything working. I looked at the outdated play-scalate module to figure out how to add Scala support to build.xml and copied its 500.scaml page for error reporting.

In order to get line-precise error reporting working, I had to wrap a try/catch around calling Scalate's TemplateEngine.layout() method. Again, most of this code was copied from the outdated play-scalate module.

case class Template(name: String) {
  
  def render(args: (Symbol, Any)*) = {
    val argsMap = populateRenderArgs(args: _*)
    
    val buffer = new StringWriter()
    var context = new DefaultRenderContext(name, scalateEngine, new PrintWriter(buffer))
    
    try {
      val templatePath = new File(Play.applicationPath+"/app/views","/"+name).toString
        .replace(new File(Play.applicationPath+"/app/views").toString,"")
      scalateEngine.layout(templatePath + scalateType, argsMap)
    } catch {
      case ex:TemplateNotFoundException => {
        if(ex.isSourceAvailable) {
          throw ex
        }
        val element = PlayException.getInterestingStrackTraceElement(ex)
        if (element != null) {
           throw new TemplateNotFoundException(name, 
             Play.classes.getApplicationClass(element.getClassName()), element.getLineNumber());
        } else {
           throw ex
        }
      }  
      case ex:InvalidSyntaxException => handleSpecialError(context,ex)
      case ex:CompilerException => handleSpecialError(context,ex)
      case ex:Exception => handleSpecialError(context,ex)
    } finally {
      if (buffer.toString.length > 0)
        throw new ScalateResult(buffer.toString,name)
    }
  }
}
...
private def handleSpecialError(context:DefaultRenderContext,ex:Exception) {
  context.attributes("javax.servlet.error.exception") = ex
  context.attributes("javax.servlet.error.message") = ex.getMessage
  try {
    scalateEngine.layout(scalateEngine.load(errorTemplate), context)
  } catch {
    case ex:Exception =>
      // TODO use logging API from Play here...
      println("Caught: " + ex)
      ex.printStackTrace
  }
}

private def errorTemplate:String = {
  val fullPath = new File(Play.applicationPath,"/app/views/errors/500.scaml").toString 
  fullPath.replace(new File(Play.applicationPath+"/app/views").toString,"")
}

Once I had this in place, error messages from Scalate are much better. Not only do I see the error in my browser, but I can click on the offending line to open it directly in TextMate.

Play Scalate Error Reporting

I've published my play-scalate module on GitHub so others can try it out. To give it a whirl, add the following to your dependencies.yml:

    - upgrades -> play-scalate 0.1

repositories:
    - upgrades:
        type: http
        artifact: "http://static.raibledesigns.com/[module]-[revision].zip"
        contains:
            - upgrades -> *

Then add with play.modules.scalate.Scalate to your controllers and call the render() method.

Summary
After using Scalate and Play for almost 3 months, I'm really enjoying the combination. When I first integrated Scalate with a simple trait, the error messages were always in the console. Now that I've borrowed some smarts from Play's ScalaController and play-scalate's error reporting, I feel like it's practically a built-in solution. I was easily able to integrate my desired SiteMesh features and it even allows reusable template blocks. In the end, it's just Scala and Scalate does a good job of allowing you to leverage that.

Other thoughts:

  • If you're writing a lot of Jade and familiar with HTML, Don Park's html2jade is a great tool that comes with Scalate support.
  • I'm really enjoying writing CSS with LESS, particularly the ability to nest rules and have programming features. The only issue I've seen is IntelliJ's LESS plugin only does code-completion for variables rather than CSS values.
  • The Play Framework Cookbook is a great reference for learning how to write modules. Not only does it explain how to create modules, it has some great real-world examples for doing bytecode enhancement, implementing message queues, using Solr and how to do production monitoring.

If this series of articles has intrigued you and you'll be at Devoxx next week, you should stop by my talk on Thursday afternoon. In addition, there's several other Play talks at Devoxx and a possible meetup on Wednesday. Check out the Devoxx, anyone? thread for more information.

Update: There's one thing I forgot to mention about the Play Scalate Module. When I had Scalate integrated in my app with a trait, I only included the scalate-core and scalate-util JARs in dependencies.yml:

- org.fusesource.scalate -> scalate-core 1.5.2-scala_2.8.1:
    transitive: false
- org.fusesource.scalate -> scalate-util 1.5.2-scala_2.8.1:
    transitive: false

However, when I created the play-scalate module, I allowed more dependencies.

- org.fusesource.scalate -> scalate-core 1.5.2-scala_2.8.1:
    exclude:
        - javax.servlet -> *
        - com.sun.jersey -> *
        - org.osgi -> *
- org.fusesource.scalate -> scalate-util 1.5.2-scala_2.8.1
Because Scalate depends on Logback, debug messages started showing up in my console. To fix this, I created conf/logback.xml in my project and filled it with the following XML.

<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
      <encoder>
          <pattern>%msg%n</pattern>
      </encoder>
  </appender>

  <root level="info">
    <appender-ref ref="STDOUT" />
  </root>
</configuration>

This reduces the logging and allows me to increase Scalate's logging if I ever have the need.

Posted in Java at Nov 07 2011, 02:07:40 PM MST Add a Comment

New MacBook Pro and iMac

Almost a month ago, I wrote about how I was hoping to increase my developer happiness by getting a new iMac and MacBook Pro. I received a lot of good advice in the comments and proceeded to order place my order with the Business Group at the Aspen Grove Apple Store the following Monday. I have to admit, the paperwork to get a lease on the equipment was kinda painful, but I was happy to get a 7% discount for being a business customer. It took until Wednesday for my order to be placed and everything started shipping the following weekend.

To make my new machines as fast as possible, I purchased OWC's Turnkey Upgrade Program for my iMac, with the 240GB OWC Mercury EXTREME Pro 6G SSD and 16GB RAM. I also ordered a 480GB Pro 6G SSD and 8GB RAM for my laptop. I received the laptop about two weeks ago and the iMac a few days later. Instead of building my new laptop from my old one, I chose to simply use Lion and copy all my apps and data over manually. I sent the iMac to OWC as soon as I received it and got it back about 3 days later. I was out of town on business last week, and when I arrived home Thursday night, I found all my new equipment waiting for me. I built my iMac by cloning the drive from my laptop and installed the new SSD and memory into my new laptop.

For the last week, I've been very happy with the speed improvements and the wicked fast snappiness of opening apps, compiling programs and IntelliJ indexing in only a few seconds. However, on October 24th, I received a strange email from Aspen Grove Business with the subject MacBook Pro Price Reduction. I quickly replied, asking if new MacBook Pro's came out in the last couple days. I received no response, but learned a couple days ago that indeed they had. One of my office mates bought a new machine and said he got a 2.5GHz processor, while mine had a 2.3GHz.

Today, I packed up my new laptop and drove down to the Aspen Grove store to see if I could exchange it for a faster one. They hesitantly agreed to exchange it, as long as I put the original hard drive and memory back into it. I drove to my office, which was only a couple miles away in downtown Littleton. I put in the original disk and memory back in and returned to the Apple Store. 20 minutes later, I was walking out with a new, new MacBook Pro and happy to get the fastest Apple laptop on the market. The funny thing about this experience is it's the 3rd time in a row I've experienced buying an Apple laptop and returning it shortly after for a newer one. My last laptop purchase (March 2009) and Trish's 13" MacBook Pro (in March) were the first two.

I'm writing this post to thank Apple for having such great customer service. I've been very close to experiencing buyer's remorse (because I missed laptop upgrades by a few days) and Apple has always been very gracious in helping me out. In fact, with this latest purchase, they said there was a $400 difference between my two-week-old laptop and the latest 2.5GHz. Then they only charged me $50 for "being such a great business customer".

Thanks Apple, you rock!

Posted in Mac OS X at Nov 06 2011, 06:10:17 PM MST 8 Comments

Happy 9th Birthday Abbie!

Abbie and I on her 9th Birthday Today we celebrated Abbie's 9th Birthday. It's hard to believe how grown up she is, but easy to love her. We had a blast celebrating with lots of her classmates and even had a magician thanks to a hookup from Greg Ostravich. Julie got her a super cute outfit for the party and smiles were shared throughout the afternoon.

Last year on Abbie's birthday is when Trish met Abbie and Jack for the first time. It's been a year and we're all still having a blast and living life to its fullest. We'll be celebrating our Kids met Trish Anniversary at the DU Hockey game tonight. A great day celebrating with great people ... I couldn't be happier. :)

To see Abbie on her birthday through the years, checkout my past Happy Birthday posts: #1, #3, #4, #5, #6, #7 and #8.

Posted in General at Nov 05 2011, 06:05:58 PM MDT 1 Comment

Play Scala's Anorm, Heroku and PostgreSQL Issues

This article is the 5th in a series on about my adventures developing a Fitness Tracking application for my talk at Devoxx in two weeks. Previous articles can be found at:

  1. Integrating Scalate and Jade with Play 1.2.3
  2. Trying to make CoffeeScript work with Scalate and Play
  3. Integrating HTML5 Boilerplate with Scalate and Play
  4. Developing with HTML5, CoffeeScript and Twitter's Bootstrap

Anorm
In my previous article, I described how I created my application's features using CoffeeScript and make it look good using Twitter's Bootstrap. Next, I turned to persisting this data with Anorm.

The Scala module includes a brand new data access layer called Anorm that uses plain SQL to make your database request and provides several API to parse and transform the resulting dataset.

I'm a big fan of ORMs like Hibernate and JPA, so having to learn a new JDBC abstraction wasn't exactly appealing at first. However, since Anorm is the default for Play Scala, I decided to try it. The easiest way for me to learn Anorm was to start coding with it. I used A first iteration for the data model as my guide and created model objects, companion objects that extended Magic (appropriately named) and wrote some tests using scalatest. I started with an "Athlete" model since I knew "User" was a keyword in PostgreSQL and that's what Heroku uses for its database.

package models

import play.db.anorm._
import play.db.anorm.defaults._

case class Athlete(
  id: Pk[Long],
  email: String, password: String, firstName: String, lastName: String
  ) {
}

object Athlete extends Magic[Athlete] {
  def connect(email: String, password: String) = {
    Athlete.find("email = {email} and password = {password}")
      .on("email" -> email, "password" -> password)
      .first()
  }

  def apply(firstName: String) = new Athlete(NotAssigned, null, null, firstName, null)
}

Then I wrote a couple tests for it in test/Tests.scala.

import play._
import play.test._

import org.scalatest._
import org.scalatest.junit._
import org.scalatest.matchers._

class BasicTests extends UnitFlatSpec with ShouldMatchers with BeforeAndAfterEach {

  import models._
  import play.db.anorm._

  override def beforeEach() {
      Fixtures.deleteDatabase()
  }

  it should "create and retrieve a Athlete" in {

      var athlete = Athlete(NotAssigned, "jim@gmail.com", "secret", "Jim", "Smith")
      Athlete.create(athlete)

      val jim = Athlete.find(
          "email={email}").on("email" -> "jim@gmail.com"
      ).first()

      jim should not be (None)
      jim.get.firstName should be("Jim")

  }

  it should "connect a Athlete" in {

      Athlete.create(Athlete(NotAssigned, "bob@gmail.com", "secret", "Bob", "Johnson"))

      Athlete.connect("bob@gmail.com", "secret") should not be (None)
      Athlete.connect("bob@gmail.com", "badpassword") should be(None)
      Athlete.connect("tom@gmail.com", "secret") should be(None)
  }

At this point, everything was fine and dandy. I could run "play test", open http://localhost/@tests in my browser and run the tests to see a beautiful shade of green on my screen. I continued following the tutorial, substituting "Post" with "Workout" and added Comments too. The Workout object shows some of the crazy-ass syntax that is Anorm getting fancy with Scala.

object Workout extends Magic[Workout] {

  def allWithAthlete: List[(Workout, Athlete)] =
    SQL(
      """
          select * from Workout w
          join Athlete a on w.athlete_id = a.id
          order by w.postedAt desc
      """
    ).as(Workout ~< Athlete ^^ flatten *)

  def allWithAthleteAndComments: List[(Workout, Athlete, List[Comment])] =
    SQL(
      """
          select * from Workout w
          join Athlete a on w.athlete_id = a.id
          left join Comment c on c.workout_id = w.id
          order by w.postedAt desc
      """
    ).as(Workout ~< Athlete ~< Workout.spanM(Comment) ^^ flatten *)

  def byIdWithAthleteAndComments(id: Long): Option[(Workout, Athlete, List[Comment])] =
    SQL(
      """
          select * from Workout w
          join Athlete a on w.athlete_id = a.id
          left join Comment c on c.workout_id = w.id
          where w.id = {id}
      """
    ).on("id" -> id).as(Workout ~< Athlete ~< Workout.spanM(Comment) ^^ flatten ?)
}

All of these methods return Tuples, which is quite different from an ORM that returns an object that you call methods on to get its related items. Below is an example of how this is referenced in a Scalate template:

-@ val workout:(models.Workout,models.Athlete,Seq[models.Comment])
-
  var commentsTitle = "No Comments"
  if (workout._3.size > 0)
    commentsTitle = workout._3.size + " comments, lastest by " + workout._3(workout._3.size - 1).author
  
div(class="workout")
  h2.title
    a(href={action(controllers.Profile.show(workout._1.id()))}) #{workout._1.title}
  .metadata
    span.user Posted by #{workout._2.firstName} on
    span.date #{workout._1.postedAt}
    .description
      = workout._1.description

Evolutions on Heroku
I was happy with my progress until I tried to deploy my app to Heroku. I added db=${DATABASE_URL} to my application.conf as recommended by Database-driven web apps with Play! on Heroku/Cedar. However, when I deployed, it failed because my database tables weren't created.

2011-10-05T04:08:52+00:00 app[web.1]: 04:08:52,712 WARN  ~ Your database is not up to date.
2011-10-05T04:08:52+00:00 app[web.1]: 04:08:52,712 WARN  ~ Use `play evolutions` command to manage database evolutions.
2011-10-05T04:08:52+00:00 app[web.1]: 04:08:52,713 ERROR ~
2011-10-05T04:08:52+00:00 app[web.1]:
2011-10-05T04:08:52+00:00 app[web.1]: @681m15j3l
2011-10-05T04:08:52+00:00 app[web.1]: Can't start in PROD mode with errors
2011-10-05T04:08:52+00:00 app[web.1]:
2011-10-05T04:08:52+00:00 app[web.1]: Your database needs evolution!
2011-10-05T04:08:52+00:00 app[web.1]: An SQL script will be run on your database.
2011-10-05T04:08:52+00:00 app[web.1]:
2011-10-05T04:08:52+00:00 app[web.1]: play.db.Evolutions$InvalidDatabaseRevision

With James Ward's help, I learned I needed to use "heroku run" to apply evolutions. So I ran the following command:

heroku run "play evolutions:apply --%prod" 

Unfortunately, this failed:

Running play evolutions:apply --%prod attached to terminal... up, run. 
5 
~        _            _ 
~  _ __ | | __ _ _  _| | 
~ | '_ \| |/ _' | || |_| 
~ |  __/|_|\____|\__ (_) 
~ |_|            |__/ 
~ 
~ play! 1.2.3, http://www.playframework.org 
~ framework ID is prod 
~ 
Oct 17, 2011 7:05:46 PM play.Logger warn 
WARNING: Cannot replace DATABASE_URL in configuration (db=$ 
{DATABASE_URL}) 
Exception in thread "main" java.lang.NullPointerException 
        at play.db.Evolutions.main(Evolutions.java:54)

After opening a ticket with Heroku support, I learned this was because DATABASE_URL was not set ("heroku config" shows your variables). Apparently, this should be set when you create your app, but somehow wasn't for mine. To fix, I had to run the following command:

$ heroku pg:promote SHARED_DATABASE 
-----> Promoting SHARED_DATABASE to DATABASE_URL... done

PostgreSQL and Dates
The next issue I ran into was with loading default data. I have the following BootStrap.scala class in my project to load default data:

class BootStrap extends Job { 
  override def doJob() { 
    import models._ 
    import play.test._ 
    // Import initial data if the database is empty 
    if (Athlete.count().single() == 0) { 
      Yaml[List[Any]]("initial-data.yml").foreach { 
        _ match { 
          case a: Athlete => Athlete.create(a) 
          case w: Workout => Workout.create(w) 
          case c: Comment => Comment.create(c) 
        } 
      } 
    } 
  } 
} 

For some reason, only my "athlete" table was getting populated and the others weren't. I tried turning on debugging and trace, but nothing showed up in the logs. This appears to be a frequent issue with Play. When data fails to load, there's no logging indicating what went wrong. To make matters worse with Anorm, there's no way to log the SQL that it's attempting to run. My BootStrap job was working fine when connecting to "db=mem", but stopped after switching to PostgreSQL. The support I got for this issue was disappointing, since it caused crickets on Play's Google Group. I finally figured out "support of Date for insertion" was added to Anorm a couple months ago.

To get the latest play-scala code into my project, I cloned play-scala, built it locally and uploaded it to my server. Then I added the following to dependencies.yml and ran "play deps --sync".

require:
    ...
    - upgrades -> scala 0.9.1-20111025
    ...

repositories:
    - upgrades:
        type: http
        artifact: "http://static.raibledesigns.com/[module]-[revision].zip"
        contains:
            - upgrades -> *

Summary
When I started writing this article, I was going to talk about some improvements I made to Scalate Play interoperability. However, I think I'll save that for next time and possibly turn it into a plugin using play-excel as an example.

As you can tell from this article, my experience with Anorm was frustrating - particularly due to the lack of error messages when operations failed. The lack of support was expected, as this usually happens when you're living on the bleeding edge. However, based on this experience, I can't help but think that it might be a while before Play 2.0 is ready for production use.

The good news is IntelliJ is adding support for Play. Maybe this will help increase adoption and inspire the framework's developers to stabilize and improve Play Scala before moving the entire framework to Scala. After all, it seems they've encountered some issues making Scala as fast as Java.

Posted in Java at Nov 02 2011, 11:54:25 AM MDT 6 Comments