Topic: Grails

A Slight Correction to using PureMVC with Vaadin

Dietrich Kappe, Monday, February 1, 2010 @ 2:32 pm

photo credit: suki_fotografiert

A while back I looked at the Vaadin Plugin and tried to make it work with the Multiton PureMVC. Back then I proposed the following code:

 
public static ApplicationFacade getInstance() {
   if (instance == null) {
     // nuke the multiton so we can do the grails recompile
     if (ApplicationFacade.hasCore(CORE)) {
       ApplicationFacade.removeCore(CORE);
     }
     instance = new ApplicationFacade(CORE);
   }
   return instance;
 }
 

A little more noodling and you'll see that doesn't work. In a multi-session environment, each user will need his own core. Furthermore, inactive cores should be harvested, otherwise we will have a memory leak.
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Software Development

Getting CloudTools to Work with Grails 1.1.1

Dietrich Kappe, Tuesday, December 22, 2009 @ 4:46 pm

photo credit: °Florian

Yes, Cloud Foundry has been acquired by Spring Source and seems to be morphing into a for-pay service, and there hasn't been a new build packaged on the Cloud Tools project page since January of 2009, but if you dig in the SVN repo, you see there's a bit of activity. Before I try building from source, I wanted to see how hard it would be to get 0.6 Grails plugin working with a Grails 1.1.1 app.

Well, harder than I thought. There's a real lack of documentation around cloudtools for one, and the radio silence on the project page over the last few months hasn't helped. Fortunately, Don over at AlterThought has put together a nice post that covers most of the pitfalls and problems with the CloudTools Grails Plugin. A few things they don't address and I thought I'd throw in here:

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Software Development

Grails and Google App Engine: Birthing Pains

Dietrich Kappe, Wednesday, November 4, 2009 @ 4:45 pm

Whenever you can get a free, publicly available place to deploy your applications, your first instinct is to grab it with both hands. Google App Engine is one of those places. Each developer can deploy up to 10 different apps in development mode.

I've been working on a grails app recently that uses the grails App Engine Plugin. Along with the GORM-JPA Plugin, which gives you some  of the usual grails GORM goodness, you can write some reasonably interesting grails apps.
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Software Development

Griffon: Convention over Configuration for the Desktop

Dietrich Kappe, Thursday, October 1, 2009 @ 1:24 pm

In the past, one of the nice things about web application development versus desktop development has been the proliferation of application development frameworks. Where desktop development pretty much gave you a set of GUI components and a few concepts like event driven programming and MVC, web frameworks, in particular the more recent ones such as Rails and Grails, gave you an application architecture into which you could implement your domain specific logic.

Lots of benefits accrued from this predefined structure, not the least of which was the ability to quickly understand the application based on a shared understanding of how applications using this framework were put together. In my experience of looking at desktop and web applications over the years, the web applications were better and more consistently designed than their desktop counterparts. Similar tries at desktop frameworks just never seemed to gain any traction (recall Scope, an app framework based on the HMVC pattern that died of neglect).

Now along comes Griffon, a desktop application framework modeled on (and sharing an architecture) with Grails. Griffon has a very similar controller, view and model breakdown as Grails, and support for plugins. I'd like to see similar frameworks for .NET and Cocoa (yes, yes, Cocoa has some of it's own framework goodness, but could use some higher level application abstractions to make application development more consistent).

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Software Development

Making Vaadin, PureMVC and Grails Work Together

Dietrich Kappe, Thursday, August 27, 2009 @ 11:16 am

On seeing that someone had developed a Grails Plugin for Vaadin (the former ITMill Toolkit, based on GWT as a front end technology), I immediately grabbed it and started exploring. One of the first things I do when developing things that look like GUI's is apply PureMVC to it. It's sort of like a big MVC switchboard that lets you hook together the smaller MVC's of whatever framework you're using. Overkill for really simple applications. Crucial for big ones.

Building a PureMVC app was pretty quick, but I ran into a small problem. Since PureMVC Multicore uses a Multiton pattern (essentially a map of Singletons), when Grails recompiles and restarts on code changes, the application barfs with a "Facade already constructed" runtime error. The solution is simple. In your subclassed org.puremvc.java.multicore.patterns.facade.Facade, change the following:

  public static ApplicationFacade getInstance() {
    if (instance == null) {
      instance = new ApplicationFacade(CORE)
    }
    return instance
  }

to this:

  public static ApplicationFacade getInstance() {
    if (instance == null) {
      // nuke the multiton so we can do the grails recompile
      if (ApplicationFacade.hasCore(CORE)) {
        ApplicationFacade.removeCore(CORE)
      }
      instance = new ApplicationFacade(CORE)
    }
    return instance
  }

And voila, your app now recompiles and runs without a hitch, just like a Grails app should. (CORE is a string constant to name your core.)

Related Services: Java Application Development, Custom Software Development

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Software Development

Asterisk-Java Testing with Groovy

Ivan Moscoso, Thursday, July 2, 2009 @ 8:03 am

Recently I have taken a bit of a detour into the world of telephony, working with Asterisk-Java, which by itself is a very valuable tool, and worth knowing a bit about if you are integrating a system with Asterisk. While it is a Java-based library, I am integrating it into a Grails application.

We have a fairly comprehensive suite of unit tests asserting that desired behaviors are triggered upon certain events initiated through the Event API. This is made even easier, as usual, with Groovy-- specifically on the testing front. Here I show two hypothetical test cases, followed by supporting code that works specifically with the Asterisk-Java classes...

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software development best practices

How to learn a new programming language or framework

Sharad Jain, Wednesday, June 17, 2009 @ 10:03 am

While never untrue, it is more of a necessity now, that a programmer should know more than just one language or framework. After being a focussed Java/J2EE developer for a long time since college, in the last couple of years, I plunged into .NET, Ruby/Rails and then Javascript/prototype/jQuery etc and now onto groovy/grails. With name like Erlang, Scala, Compass, git, blueprint, flex flying around us everywhere, it can be overwhelming and we need a plan to pick, peruse, acquire them. Here is a list of things I do when learning a new skill.

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Software Development

Grails: Custom Parent/Child Aware Tags

Anthony Caliendo, Wednesday, June 3, 2009 @ 6:56 am

Recently, I needed to create a special tag in Grails which would render specific children in a way that is aware of their order. I wanted to stick entirely with markup (not passing an array to a tag), and also wanted to avoid putting lots of logic inside a .tag file. While it was possible to write a tag lib which first parsed the children in a "non-render" mode, I preferred a solution which did not require doing my own parsing before render. The solution I came up with isn't the most flexible, but it got the job done in a relatively clean way with minimal custom code.

The following is an example solution with the associated code and tests.
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Technologies and Platforms

Week in Review

Dietrich Kappe, Sunday, March 15, 2009 @ 6:56 pm

Some interesting posts from around the blogosphere:

• The GWT Plugin for Grails has been stuck in version 1.4.x of GWT for forever. Michael Galping has published a two part (one and two) series at IBM Developerworks on integrating Grails and GWT 1.5.3. Extensive, well illustrated with full source code available for download.
• InfoQ has published an interesting conversation about Ajax and COMET versus HTML Web Sockets, i.e. hacky COMET versus real bi-directional communication mechanisms between the server and browser.
• UXDesign.com has a concise summary of an Alan Cooper Interview video from 2008. User Experience Design, baby!
• David Hamill has some provocative musing on the difference between usability and user experience design. Not sure I agree with everything he has to say, but it's a question that comes up often and is worth thinking about.
• A bit older, but I just came across it: the original ScrumMaster, Jeff Sutherland, has an interesting article about ROI and incremental development. The conclusion? Incremental is better. But seriously, we don't have enough rigorous thinking and writing about how good design and process reduces the cost of software in the long term (while perhaps increasing it in the short term).

These were some of the posts that I found valuable over the last week. Please share yours in the comments.

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Software Development

Grails: Delegating to GORM Persistence in Java

Anthony Caliendo, Wednesday, February 11, 2009 @ 11:43 pm

For a recent project, I needed to plug some Java code into a Grails app. I wanted to use GORM for persistence, but couldn't introduce the interfaces, proxies, and factories into the java code which is required for existing solutions to this problem.

Basically, my constraint was that the java code itself couldn't be altered to work inside the grails app. The solution I came up with is pretty simple, but works well.

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Software Development

Grails and JSONP: How Easy is That?

Dietrich Kappe, Friday, February 29, 2008 @ 4:15 pm

For all of those Java developers casting longing glances at their buddies doing Rails development, there is hope. Grails, which has just celebrated its 1.0 release, is a Rails-like "convention over configuration" framework that aims to do for the Java world what Rails has done for Ruby. Instead of Ruby, the dynamic programming language of choice is Groovy, which compiles to bytecode (no Groovy to Java translation) and integrates smoothly with just about any Java code you may be using.

I'll stop hyping Groovy and Grails in general here; there's plenty of good informational stuff on the Grails and Groovy home pages. I will note that if you run off the tracks a little bit, you can find yourself reading through 500-odd line stack traces of Groovy, Spring and Hibernate -- there's room for some improvement there.

One of the many nice things about Grails is it's support for JSON and XML. Let me put together a simple example that shows off some of Grails' power.

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Software Development