Raible Designs

Devoxx France: A Great Conference in a Magnificent City

This week, my lovely fiancé and I traveled to the City of Light. Our journey was designed around some speaking engagements at Devoxx France. Devoxx is one of my favorite conference franchises and Devoxx France has been special to me ever since the Devoxx (Belgium) I spoke at in 2011.

2011 was the year I spoke about my experience with Play, Scala, CoffeeScript and Jade. I wrote the presentation on my flight over, composed the demo video the night before and made it all happen in the nick of time. Of course, this was after 120 hours of research and preparation, so the presentation composition process had all the data I needed. You can imagine my sense of relief after pulling off that talk and getting an enthusiastic applause from the audience for my efforts.

One of the first audience questions I received was from Nicolas Martignole, asking if I'd speak at Devoxx France the following year. I whole-heartedly agreed to do it and was excited for the opportunity. It was with great disappointment that I later found out I couldn't attend Devoxx France in 2012. My client didn't like me taking so much time off and I agreed to scale my two week vacation back to 1 week. This year, I was determined to go, so I submitted some of my favorite talks: Comparing JVM Web Frameworks and The Play vs. Grails Smackdown with James Ward. I was extremely pleased when they both got accepted.

Side Story: I met Martin Odersky shortly when he sat down next to me for the Java Posse presentation in Belgium in 2011. After shaking his hand and introducing myself, I had to politely ask him to leave because it was Trish's seat. Talk about awkward; but Martin was very gracious and promptly found a new seat close by.

I took out the parts of the presentation that've pissed people off in the past - particular the JSF bashing by James Gosling, the Rails gushing from Craig McClanahan and the Pros and Cons sections of each framework. I added the history of web frameworks and research from InfoQ and devrates.com.

The best part of the JVM Web Frameworks talk was the audience's reaction and enthusiasm. Devoxx always seems to attract passionate developers and Devoxx France was no different. Developers packing the room, clapping after your intro, laughing at your jokes, signifying that they agree with you about JSF. As a speaker, it's an unbelievable experience.

You can view my Comparing JVM Web Frameworks presentation below or on Slideshare.net.

Play Frameworks vs. Grails Smackdown
To prepare for James Ward and my Play vs. Grails Smackdown, we had a number of goals. First of all, we wanted to update our apps to use the latest versions of each framework. I documented what it took for Grails, James just checked in his code to GitHub. It was interesting to see that Grails 2.0.3 -> 2.2.1 caused a number of issues with testing, while Play 2.0.3 -> Play 2.1.0 required API changes, but nothing for tests. Secondly, we updated all the stats for our pretty graphs and ran load tests again.

This is where the fun started. On Tuesday evening, I decided to challenge the notion that Play was twice as fast as Grails. James had proven this with Apache Bench tests. With Play 2.0 and Grails 2.0 (last summer), we clocked Play at 251/requests per second and 198 for Grails. After upgrading each app to the latest releases, we found the numbers to be 233/second for Play and 118 for Grails.

However, Apache Bench only tests until the first byte is received. Since I've done a lot of browser optimizations recently, I fired up whichloadsfaster.com, captured a screenshot and added it to our presentation. The next day, James added a CDN and a bunch of caching to his app and re-ran his AB tests.

Now he was smoking Grails, so I added a CDN and caching as well. However, the best I could do was just over 1000/requests per second, while he was around 2200/second. When he ran live tests during our talk, Play was around 2800/sec and Grails was around 900.

It was great to see how much better performance we could get with caching and a CDN. The best part is this should be available to most applications, not just these frameworks. By adding a CDN (we used Amazon CloudFront) and caching, we were both able to 10x the performance of our apps. You can find out presentation online at http://ubertracks.com/preso or view it below.

Summary
This was a very enjoyable conference to attend as a speaker. First of all, it was in one of the most beautiful cities in the world, but it's also a very special place for Trish and I. We got engaged just outside of Paris in Versailles after the last Devoxx conference I spoke at. Trish has some amazing photos from that trip. Secondly, the Devoxx conference attracts a special kind of developer - one that is passionate about and eager for knowledge. Lastly, speaking with my good friend James, in an exotic city about something we love - that was special. Asking for beers and having them brought to us at the start of our Smackdown. That was magical (thanks Nicolas!).

To all the Devoxx organizers and crew - well done on a great show!

Upgrading Grails from 2.0 to 2.2

In preparation for my Grails vs. Play Smackdown at Devoxx France next week, I recently upgraded my Grails version of Happy Trails from Grails 2.0.3 to Grails 2.2.1. I ran into a few issues along the way and figured I'd document them here to help others out.

Fixing the source
The first issue I ran into was Spock and Groovy 2 incompatibilities.

| Resolving plugin JAR dependencies
| Error WARNING: Dependencies cannot be resolved for plugin [mail] due to error: startup failed:
Could not instantiate global transform class org.spockframework.compiler.SpockTransform specified at jar:file:/Users/mraible/.grails/ivy-cache/org.spockframework/spock-core/jars/spock-core-0.7-groovy-1.8.jar!/META-INF/services/org.codehaus.groovy.transform.ASTTransformation  because of exception org.spockframework.util.IncompatibleGroovyVersionException: The Spock compiler plugin cannot execute because Spock 0.7.0-groovy-1.8 is not compatible with Groovy 2.0.7. For more information, see http://versioninfo.spockframework.org

I posted the problem to StackOverflow and got a response almost immediately. While this pull request helped me quite a bit, it was ultimately caused by my vision: I had two "geb-spock" dependencies listed in BuildConfig.groovy with different groupIds.

At this point, I also moved all my plugin dependencies from application.properties to BuildConfig.groovy.

The next problem I ran into was a unit test and functional tests failing. The unit testing issue was caused by my Direction model not being in the tests @Mock annotation. After I added it, validation kicked and I recognized my test was invalid. I added @Ignore and continued.

The functional test seemed to be seemed to be caused by Geb and it trying to use the Chrome Driver. One of my tests didn't work with the default HtmlUnitDriver, so I used the ChromeDriver for the one test.

| Running 11 spock tests... 6 of 11
| Failure:  signup as a new user(happytrails.AuthenticatedUserSpec)
|  org.openqa.selenium.WebDriverException: Unable to either launch or connect to Chrome. Please check that ChromeDriver is up-to-date. Using Chrome binary at: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome (WARNING: The server did not provide any stacktrace information)
Command duration or timeout: 45.66 seconds
Build info: version: '2.27.0', revision: '18259', time: '2012-12-05 11:30:53'
System info: os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.8.2', java.version: '1.7.0_04'
Driver info: org.openqa.selenium.chrome.ChromeDriver
    at org.openqa.selenium.remote.ErrorHandler.createThrowable(ErrorHandler.java:187)
    at org.openqa.selenium.remote.ErrorHandler.throwIfResponseFailed(ErrorHandler.java:145)
    at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:533)
    at org.openqa.selenium.remote.RemoteWebDriver.startSession(RemoteWebDriver.java:216)
    at org.openqa.selenium.remote.RemoteWebDriver.(RemoteWebDriver.java:111)
    at org.openqa.selenium.remote.RemoteWebDriver.(RemoteWebDriver.java:115)
    at org.openqa.selenium.chrome.ChromeDriver.(ChromeDriver.java:161)
    at org.openqa.selenium.chrome.ChromeDriver.(ChromeDriver.java:107)
    at happytrails.AuthenticatedUserSpec.signup as a new user(AuthenticatedUserSpec.groovy:25)

Even when running "grails -Dgeb.env=chrome test-app", this still happened. This was caused by the fact that I had GebConfig.groovy in test/functional/happytrails. Move it to test/functional solved the problem. I also discovered that I know longer needed Chrome to get this test to pass. Apparently, the HtmlUnitDriver has issues with Grails 2.2, but it seems to work for me.

After getting the Geb configuration fixed, I ran into a functional test failure:

| Running 11 spock tests... 5 of 11
| Failure:  click signup link(happytrails.AuthenticatedUserSpec)
|  org.openqa.selenium.ElementNotVisibleException: Element must be displayed to click (WARNING: The server did not provide any stacktrace information)

Even though I could see the "signup" link when I ran "grails run-app", I could see that it didn't show up when running tests in Chrome. This turned out to be caused by an extraneous <div class="nav-collapse"> I had in my main.gsp. Removing it solved the problem. It's strange that this never showed up with Grails 2.0. My only guess is that Geb someone didn't look at the visibility of the element.

The last testing-related issue I ran into was a InvalidElementStateException:

| Running 11 spock tests... 7 of 11
| Failure:  add new route to region(happytrails.AuthenticatedUserSpec)
|  org.openqa.selenium.InvalidElementStateException: Element must be user-editable in order to clear it. (WARNING: The server did not provide any stacktrace information)

I was able to fix this by changing AddRoutePage.groovy from:

static content = {
    createButton(to: ShowRoutePage) { create() }
    name { value("Name") }
    distance { value("Distance") }
    location { value("Location") }
}

To:

static content = {
    createButton(to: ShowRoutePage) { create() }
    form { $("form") }
}

And then referencing name, distance and location accordingly (form.name, etc.) in AuthenticatedUserSpec.groovy.

CloudBees
After I had everything working locally, I logged into Jenkins on CloudBees. Since I hadn't used it in a while, I had to wait a bit while my Jenkins server was re-commissioned. Once it was up, I tried to select Grails 2.2.1 to build with, but found it wasn't available. After a tweeting this, I learned about Grails Wrapper, found that the latest Grails Jenkins plugin supported it and got everything working. I later discovered that CloudBees does support Grails 2.2.1, I just needed to setup another Grails installation to automatically download and install 2.2.1.

Heroku
The last two issues I ran into were with Heroku. Since I was upgrading everything, I wanted Grails to build/run under Java 7 and use Servlet 3. I changed the appropriate properties in BuildConfig.groovy, configured Heroku and deployed. No dice.

Error Compilation error: startup failed:
Invalid commandline usage for javac.
javac: invalid source release: 1.7
Usage: javac  
use -help for a list of possible options

Sidenote: I tried building with Java 8 on CloudBees, but discovered the searchable plugin doesn't support it.

Compile error during compilation with javac.
/scratch/jenkins/workspace/Happy Trails - Grails 2/work/plugins/searchable-0.6.4/src/java/grails/plugin/searchable/internal/compass/index/DefaultUnindexMethod.java:94: error: reference to delete is ambiguous
                    session.delete(query);
                           ^
  both method delete(CompassQuery) in CompassOperations and method delete(CompassQuery) in CompassIndexSession match

As far as Servlet 3, it was pretty obvious that the Jetty version Heroku uses for Grails doesn't support it. Therefore, I reverted back to Servlet 2.5.

java.lang.NoClassDefFoundError: javax/servlet/AsyncContext
	at org.codehaus.groovy.util.LazyReference.getLocked(LazyReference.java:46)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2444)

I sent the Java 7 issue to Heroku Support a few days ago but haven't heard back yet.

Summary
While upgrading Grails from 2.0 to 2.2 wasn't as easy as expected, it is understandable. After all, Grails 2.2 ships with Groovy 2.0, which has a bunch of new features itself. All the issues I ran into were fairly easy to solve, except for Java 7 on Heroku. But hey, what do you expect from a free hosting service?

If you're at Devoxx France next week, I look forward to sharing our research on Grails 2.2.1 vs. Play 2.1.0.

Play vs. Grails Smackdown at ÜberConf

Play and Grails have been hyped as the most productive JVM Web Frameworks for the last couple of years. That hype has recently grown thanks to both frameworks' 2.0 releases. That's why James Ward and I decided to do a presentation at ÜberConf comparing the two. In April, we proposed the talk to Jay Zimmerman, got accepted and went to work.

How we did it
In the beginning of May, we met at a brewery in LoDo and sketched out the app we wanted to build. We also came up with a schedule for development and a plan for the presentation. We decided to build two different webapps, each with little-to-no Ajax functionality and a few features that we could use to load test and compare the applications.

We started out with the name “Happy Trails” since we both liked trails and happy hours. Later, James found that www.ubertracks.com was available and purchased the domain. We setup the Grails app to be on bike.ubertracks.com and Play/Java to be on hike.ubertracks.com. We managed our source code on GitHub, continuously tested on CloudBees and deployed to Heroku. Two weeks ago, when we were finishing up our apps, we hired a friend (Linsay Shirley) to do QA.

After fixing bugs, I emailed Patrick Lightbody, got some “cloud dollars” for Neustar Web Performance and started running load tests. The Wednesday before last, at 2 in the morning, I recorded a simple browsing regions and routes script and set it to go to 50 users over a 5 minute period and then sustain 50 for another 5 minutes. It was fun to watch the log messages whiz through my console so fast they got blurry. About halfway through testing the Grails app, there was an OOM issue, but it eventually recovered. Limiting db connections to 4 and scaling to 5 Dynos in future tests helped alleviate any issues.

We took our development experience, the load/performance testing data, and a bunch of ecosystem stats and built our smackdown presentation. We used reveal.js, GitHub Files and Google Charts to make things more dynamic.

What we found
We arrived at a number of conclusions after doing our research:

Code

• From a code perspective, Play 2 and Grails 2 are very similar frameworks.
• Code authoring was good in both, but lacking IDE support for Play 2's Scala Templates.
• Grails Plugin Ecosystem is excellent.
• TDD-Style Development is easy with both.
• Type-safety in Play 2 was really useful, especially routes.

Statistical Analysis

• Grails has better support for FEO (YSlow, PageSpeed)
• Grails has less LOC! (6 lines less, but 40% more files)
• 1 Dyno - Grails had 2x transactions!
  • Grails experienced OOM about halfway through.
• Apache Benchmark with 10K requests:
  • Play: ~10% failed requests, Grails: 0
  • Requests per second: {Play: 170, Grails: 198}
  • Requests per second: {Play: 251, Grails: 198}
• Load Test with 100 Real Users:
  • Grails: 10% more transactions, 0 errors

Ecosystem Analysis

• "Play" is difficult to search for.
• Grails is more mature.
• Play has momentum issues.
• LinkedIn: more people know Grails than Spring MVC.
• Play has 3x user mailing list traffic.
• We had similar experiences with documentation and questions.
• Outdated documentation is a problem for both.
• Play has way more hype!

We figured we spent around 100 hours developing the apps, gathering data and creating the presentation. The good news is it's all open source! This means you can clone the project on GitHub (Grails is in the grails2 branch, Play is in the play2_java branch) and help us improve it. The presentation is in the master branch in the preso directory.

All the data we gathered is open for debate and we’d love to tune our apps to handle more requests per second. In fact, we already had a contributor discover an issue and provide a fix for Play that increases its throughput from 170 req/second to 252 req/second!

Regardless of what the stats and pretty graphs say, we both enjoyed our experiences with Play 2 and Grails 2. If you haven't tried them yourself, we encourage you to do so.

Livin' it up in Vegas at TSSJS 2011

Last Wednesday, Trish and I traveled to Las Vegas for TheServerSide Java Symposium 2011 conference. We had a free room from TechTarget, but opted to upgrade to a suite with a view over the Bellagio Fountains. Trish won a trip to Vegas as a sales award earlier in the year and cleverly exchanged it for cash, so our upgrade was sort of free.

After I finished speaking, we headed to happy hour and met up with some friends that happened to be in town. We had dinner at the Todd English Pub and headed to the Penn & Teller show at the Rio. We closed the night after Trish had a 45-minute roll at the craps table at O'Sheas.

We slept in on Thursday and I gave my Comparing JVM Web Frameworks talk that afternoon. I made sure to mention some other methods to choosing web frameworks: doing performance comparisons like Peter Thomas has done or choosing Lift because one of its developers says it's the best. While Vaadin did sneak into the #5 spot, I made sure and mentioned that Wicket and Tapestry seem to belong there moreso (based on stats, mailing list traffic, etc.).

Trish took a bunch of pictures during my talk, which had a great turnout and lots of participation.

That evening, we celebrated St. Patty's Day with some college buddies of mine, ate great sushi at Mizuya and experienced the joys of three card poker. Thanks to TechTarget for inviting me to TSSJS 2011; we had an awesome time. You can find all the pictures we took on Flickr.

P.S. If you can't see the presentations in this post (a.k.a. you don't have Flash), you can view them on on Slideshare or download the PDFs.

How I Calculated Ratings for My JVM Web Frameworks Comparison

When I re-wrote my Comparing JVM Web Frameworks presentation from scratch, I decided to add a matrix that allows you to rate a framework based on 20 different criteria. The reason I did this was because I'd used this method when choosing an Ajax framework for Evite last year. The matrix seemed to work well for selecting the top 5 frameworks, but it also inspired a lot of discussion in the community that my ratings were wrong.

I expected this, as I certainly don't know every framework as well as I'd like. The mistake I made was asking for the community to provide feedback on my ratings without describing how I arrived at them. From Peter Thomas's blog:

What you are doing is adjusting ratings based on who in the community shouts the loudest. I can't help saying that this approach comes across as highly arrogant and condescending, you seem to expect framework developers and proponents to rush over and fawn over you to get better ratings, like waiters in a restaurant trying to impress a food-critic for Michelin stars.

I apologize for giving this impression. It certainly wasn't my intent. By having simple numbers (1.0 == framework does well, 0.5 == framework is OK and 0 == framework not good at criteria) with no rationalization, I can see how the matrix can be interpreted as useless (or to put it bluntly, as something you should wipe your ass with). I don't blame folks for getting angry.

For my Rich Web Experience presentation, I documented why I gave each framework the rating I did. Hopefully this will allow folks to critique my ratings more constructively and I can make the numbers more accurate. You can view this document below or on Google Docs.

In the end, what I was hoping to do with this matrix was to simply highlight a technique for choosing a web framework. Furthermore, I think adding a "weight" to each criteria is important because things like books often aren't as important as REST support. To show how this might be done, I added a second sheet to the matrix and made up some weighting numbers. I'd expect anyone that wants to use this to downloaded the matrix, verify the ratings are accurate for your beliefs and weight the criteria accordingly.

Of course, as I and many others have said, the best way to choose a web framework is to try them yourself. I emphasized this at the end of my presentation with the following two slides.

My Comparing JVM Web Frameworks Presentation from Devoxx 2010

This week, I've been having a great time in Antwerp, Belgium at the Devoxx Conference. This morning, I had the pleasure of delivering my Comparing JVM Web Frameworks talk. I thoroughly enjoyed giving this presentation, especially to such a large audience. You can view the presentation below (if you have Flash installed) or download it here.

Unlike previous years, I chose to come up with a spreadsheet matrix that shows why I chose the 5 I did. This spreadsheet and rankings given to each framework are likely to be debated, as I don't know all the frameworks as well as I'd like to. Also, the missing column on this spreadsheet is a "weighting" column where you can prioritize certain criteria like I've done in the past when Comparing Ajax Frameworks. If you believe there are incorrect numbers, please let me know and I'll try to get those fixed before I do this talk again at The Rich Web Experience.

One thing that doesn't come across in this presentation is that I believe anyone can use this matrix, and weightings, to make any of these frameworks come out on top. I also believe web frameworks are like spaghetti sauce in The Ketchup Conundrum. That is, the only way to make more happy spaghetti sauce lovers was to make more types of spaghetti sauce. You can read more about this in my There is no "best" web framework article.

Update: If you disagree with the various ratings I gave to web frameworks in this presentation, please provide your opinions by filling out this survey. Thanks to Sebastien Arbogast for setting this up.

Update: Sebastien has posted his survey results at JVM Web Framework Survey, First Results.

Update 12/6: A video of this presentation is now available on Parleys.com.

P.S. My current gig is ending in mid-December. If you're looking for a UI Architect with a passion for open source frameworks, please let me know.

My Presentations from The Irish Software Show 2010

This week I've been enjoying Dublin, Ireland thanks to the 2nd Annual Irish Software Show. On Wednesday night, I spoke about The Future of Web Frameworks and participated in a panel with Grails, Rails, ASP.NET MVC and Seaside developers. It was a fun night with lots of lively discussion. Below is my presentation from this event.

This morning, I delivered my Comparing Kick-Ass Web Frameworks talk. This presentation contains updated statistics for various metrics comparing Rails vs. Grails and Flex vs. GWT.

Thanks to all who attended my talks this week!

P.S. I believe audio was recorded on Wednesday night, but I'm unsure how it turned out. I'm pretty sure no recordings were done on this morning's session.

Reviews for Grails: A Quick-Start Guide and Kanban and Scrum

A couple weeks ago, I had a business trip from Denver to Washington, DC. Since I didn't have any coding to do on the flight, I brought along a couple books and was surprisingly able to finish them both en route. Tech books that can be read in a single flight are my favorite. Another book I recall doing this with was First Steps in Flex back in December.

The books I read were Dave Klein's Grails: A Quick-Start Guide and Henrik Kniberg and Mattias Skarin's Kanban and Scrum minibook. Below are short reviews of each book.

Grails: A Quick-Start Guide
I've developed a few Grails applications, so I didn't expect to learn a whole lot from this book, but I was pleasantly surprised. Not only did it introduce all the basic concepts in a clear and concise way, it actually made it fun to read. The first chapter does a good job of introducing Groovy; showing you how to use closures and the easy-to-use collections API. From there, you dive into learning about the project, which is actually a real-life web application called TekDays.com. Then the foundational Iteration Zero is planned and executed.

In Chapter 3, you dive right into creating domain classes and their relationships. All the different mapping types are covered: one-to-one, one-to-many and the good ol' many-to-many. Since this is often a difficult part of an application, it's always nice to see how much Grails simplifies it. I liked the Ajax section in Chapter 7 and especially the part where it showed how to do a TagLib to show threaded comments in a forum.

Chapter 7 (Security) was a little disappointing in that it showed how to hand-roll your own security rather than using the Spring Security plugin (formerly Acegi) or the Shiro plugin (formerly JSecurity). I'd especially have liked to see how to do Ajax authentication where a token is generated for the client and included as a header in each subsequent request.

Other than that, I really enjoyed Chapter 10 where I learned how to implement search using dynamic finders, Hibernate's Criteria API and the Searchable Plugin (which gets its awesomeness from Compass). Implementing Compass in Java requires many, many annotations. In Grails, it's as simple as adding the following to your domain class.

static searchable = true

I truly enjoyed this book, especially with its Agile Development patterns that used iterations to get things done. Grails: A Quick-Start Guide is a code-intensive journey that gets up you to speed on Grails quickly and efficiently. It's very much like the framework itself. It eliminates the yak shaving and allows you learn without distractions. Kudos to Dave Klein for creating such an enjoyable and easy-to-read book.

Kanban and Scrum
In my career, I've used Scrum on quite a few projects. Of course, it's not the processes that typically make a team successful. Rather, it's often the gelling of the team members, as well as respect for coding practices that are proven to create higher quality code - specifically TDD and pair programming. Before reading this book, I'd heard a bit about Kanban, most of it from Marty Haught's Lean Teams: Doing more with less presentation.

This book did a great job of showing the differences between the two approaches: how Scrum promotes iterations whereas Kanban promotes cycle time. The most interesting part of the book is the Case Study in the 2nd half. This section shows how a team used various techniques to develop a well-oiled development machine. I think the most important thing to note from this section is how the team was willing to change, learn and grow based on their experiences - in a very rapid fashion.

In my current gig, I'm helping a team of developers move from waterfall to agile processes. We're leveraging many aspects of Scrum and agile by using a coach, iterations, daily standups, TDD, continuous integration and creating "as built" documentation when we finish developing a feature. The "As Built" documentation is something I picked up from working at Chordiant and I've found it to be a great way of education developers (and outsiders) how things were done in an iteration.

One thing we've seen in our first few weeks is that iterations don't work for all teams or individuals. A Kanban model fits much better for them. Having a Kanban board allows them to visualize (and control) their workload in a much more efficient manner. We haven't started implementing actual boards on a wall, we're just using spreadsheets for now. However, we do have two Agile Coaches starting this week so I expect things to improve rapidly.

Back to the book. More than anything, I enjoyed reading this book because it made me excited about the changes I'm helping implement and I believe in many of the practices in both Scrum and Kanban. I enjoy iterations and structured expectations around development, but I can see how Kanban would work better for folks in operations and infrastructure. I look forward to implementing the best parts of both worlds and hopefully a similar Case Study of what worked and what didn't. With any luck, we'll be able to learn, evolve and produce at a much higher level than previous waterfall practices achieved.

Grails OAuth and LinkedIn APIs

Back in November, I wrote about how to talk to LinkedIn APIs with GWT. A week later, I figured out how to do it with Grails and contributed a patch to the grails-oauth plugin.

Since then, a few folks have asked how I did it. Since code speaks louder than words, I took some time and 1) verified the oauth plugin works as expected and 2) created an example application demonstrating functionality. You can find the results in my fork of grails-oauth on GitHub. You can also view the example online.

Below is a quick tutorial explaining how to integrate LinkedIn into your Grails application.

1. Download and install Grails 1.1.2.
2. Run grails create-app to create your application.
3. Add the following to the bottom of grails-app/conf/Config.groovy:

   oauth {
       linkedin {
           requestTokenUrl="https://api.linkedin.com/uas/oauth/requestToken"
           accessTokenUrl="https://api.linkedin.com/uas/oauth/accessToken"
           authUrl="https://api.linkedin.com/uas/oauth/authorize"
           consumer.key="XXX"
           consumer.secret="XXX"
       }
   }
   

   You can get your consumer.key and consumer.secret at https://www.linkedin.com/secure/developer. Make sure to set the OAuth Redirect URL to http://localhost:8080/{your.app.name}/oauth/callback for testing.
4. Download the oauth-plugin, extract it and build it using grails package-plugin. Install it in your project using grails install-plugin path/to/zip.
5. Add a link to the GSP you want to invoke LinkedIn Authentication from:

   <g:oauthLink consumer='linkedin' returnTo="[controller:'profile']">
       Login with LinkedIn
   </g:oauthLink>
   

6. Create grails-app/controllers/ProfileController.groovy to access your LinkedIn Profile.

   class ProfileController {
       def apiUrl = "http://api.linkedin.com/v1/people/~"
       def oauthService
       
       def index = {
    
           if (session.oauthToken == null) {
               redirect(uri:"/")
           }
    
           if (params?.apiUrl) apiUrl = params.apiUrl
           
           def response = oauthService.accessResource(
                   apiUrl, 'linkedin', [key:session.oauthToken.key, secret:session.oauthToken.secret], 'GET')
    
           render(view: 'index', model: [profileXML: response, apiUrl: apiUrl])
       }
    
       def change = {
           if (params?.apiUrl) {
               println("Setting api url to " + params.apiUrl)
               apiUrl = params.apiUrl
           }
           
           redirect(action:index,params:params)
       }
   }
   

7. Create grails-app/views/profile/index.gsp to display the retrieved profile and allow subsequent API calls.

   <html>
   <head><title>Your Profile</title></head>
   <body>
   <a class="home" href="${createLinkTo(dir:'')}">Home</a>
   <g:hasOauthError>
       <div class="errors">
           <g:renderOauthError/>
       </div>
   </g:hasOauthError>
   
   <g:form url="[action:'change',controller:'profile']" method="get">
       Your LinkedIn Profile:
       <textarea id="payload" style="width: 100%; height: 50%; color: red">${profileXML}</textarea>
       <p>
           <g:textField name="apiUrl" value="${apiUrl}" size="100%"/>
           <br/>
           <g:submitButton name="send" value="Send Request"/>
       </p>
   </g:form>
   </body>
   </html>
   

8. Start your app using grails run-app and enjoy.

As mentioned earlier, you can download the grails-oauth-example or view it online.

One improvement I'd like to see is to simplify the parsing of XML into a Profile object, much like the linkedin gem does for Rails.

If you're interested in learning more about LinkedIn and OAuth, I encourage you to checkout Taylor Singletary's presentation LinkedIn OAuth: Zero to Hero.

Update: I updated the oauth-plugin so it's backwards-compatible with OAuth 1.0 and added Twitter to the example application to prove it. If you're seeing "Cannot invoke method remove() on null object", it's likely caused by your redirect URL pointing to an application on a different domain.

Comparing Kick-Ass Web Frameworks at The Rich Web Experience

Yesterday, I delivered my Comparing Kick-Ass Web Frameworks talk at the Rich Web Experience in Orlando, Florida. Below are the slides I used:

Although it's difficult to convey a presentation in a slide deck, I can offer you my conclusion: there is no "best" web framework. I believe web frameworks are like spaghetti sauce in that everyone has different tastes and having so many choices is necessary to satisfy everyone. You can read more about the plural nature of perfection in Malcolm Gladwell's The Ketchup Conundrum (a written version of What we can learn from spaghetti sauce). Even though there is no "best" web framework, I believe GWT, Flex, Rails and Grails are frameworks that every web developer should try. They really do make it fun to develop web applications.

You can find the slides for my other RWE talk at Building SOFEA Applications with GWT and Grails.

Kudos to Jay Zimmerman for putting on a great show in Orlando this year. I had a great time talking with folks and learning in the sessions I attended. I particularly enjoyed bringing my parents and kids and staying at such a nice resort. Disney World (Magic Kingdom) and Universal Studios was very enjoyable due to the short lines. Also, the weather was perfect - especially considering the freezing cold in Denver this week.