Category Archives: Groovy/Grails

Grails/BlazeDS/Flex/iPhone Full Stack Part 2/3

In the previous episode, we built a simple Grails backend for the todolist application. In this installment, we will create a simple Flex 4 front-end for this backend.

The following assumes that you have already installed Flash Builder 4 (formerly known as Flex Builder), either in standalone mode or as an Eclipse plug-in.

Continue reading Grails/BlazeDS/Flex/iPhone Full Stack Part 2/3

Grails/BlazeDS/Flex/iPhone Full Stack Part1/3

A couple of years ago, I published an article on this blog entitled “Flex, Spring and BlazeDS: the full stack!” and this article became very popular. Actually it broke my daily visits record. Today I’m gonna try to break this record again.

In the last couple of years, I’ve worked a lot with Flex and Spring. But in my eternal quest for productivity and user experience, I discovered Grails. Based on the same ideas as Ruby on Rails or Django, it combines a dynamic language – Groovy – with the power of “convention over configuration” to make it possible to create web applications in no time, thus allowing you to spend more time on your user experience.

Of course it’s not the only thing that has changed since then. Flex 4 is now finally out in the open. BlazeDS 4 too. And Flash Builder is finally productive enough for me to use it… in combination with IntelliJ IDEA of course.

All those evolutions in my toolset needed to be integrated, so I ended up building a Grails plugin to do just that: Grails BlazeDS plugin. And since this plugin could not be officially released without a proper demonstration, here we are.

I prepared this tutorial for a BeJUG talk I gave last week. So I want to thank Stephan Janssen and the BeJUG for inviting me… and for staying with me without throwing vegetables at me, given all the failures I had during the live coding session. For those of you who were there: I clearly identified PermGen space as the guilty part responsible for all these blank screens. In fact, since Grails migrated from Jetty to Tomcat as their runtime server, default java memory settings are not enough anymore, so I always configure my projects for that, but of course, in live, I forgot…

Anyway. I’m going to publish this tutorial in three episodes, each one of them being accompanied by its very own screencast on Vimeo (damn Youtube and their 10-minute limit!). But I’ll also publish the tutorial transcript right here for those who want to go faster.

Important note: this tutorial covers the following set of technologies in the specified versions:

In particular, it seems that Grails 1.3 that was just released a couple of days ago breaks Grails BlazeDS plugin. I’ll update both my plugin and this tutorial when I can make them all work together again.

Continue reading Grails/BlazeDS/Flex/iPhone Full Stack Part1/3

Grails BlazeDS 4 Integration Plugin

One of the main goals I’ve been pursuing for a few months is the integration of Grails with Flex 4. I need to rework ConferenceGuide‘s administration backend to make it more ergonomic so that we can cover more events, and ever since I discovered Flex 4 niceties, I couldn’t think of doing that with anything else. The problem is that none of the existing plugins suited my needs. All of them cover Flex 3 only, some of them introduce a lot of complexity for CRUD generation, some of them use GraniteDS instead of BlazeDS, and the simplest plugin, grails-flex has never gone further than the experimental stage. I did a lot of experiments, talked a lot about it on Grails mailing lists, until Tomas Lin kindly explained to me that maybe I was approaching it the wrong way. I wanted a plugin that would set up a complete environment for Flex developement right in the middle of my Grails application. And I wanted that because I wanted to avoid using Flash Builder (you know… Eclipse… ierk!), mainly because the only advantage of Flex Builder 3 over IntelliJ Idea was the visual designer. But he was right, I was wrong. Flash Builder 4 DOES change everything. It does include a lot of very interesting features that greatly improve Flex development productivity, especially when it comes to integration with backend technologies. And for those features, I can only admit that IntelliJ is not up to par yet. I’m still gonna use it for the Grails part, but Flash Builder will be my environment of choice for Flex 4.

So, once I learnt more about Flex 4, BlazeDS 4 and Flash Builder 4 beta 2, it was time to reconsider my approach and develop a much simpler Grails plugin so that any Grails application could be used in combination with Flash Builder. I just released grails-blazeds plugin to do just that. Here is how it works:

  1. Install grails-blazeds plugin: “grails install-plugin blazeds”. This plugin copies a couple of configuration files into your application and imports all of the required libraries, including BlazeDS 4 and Spring-BlazeDS integration 1.5, both in nightly snapshot versions, since they have not been officially released yet
  2. Create a service to be exposed to your Flex application over AMF, or choose an existing one
  3. Add @RemotingDestination annotation to your service class, and @RemotingInclude annotation to all of the methods in this service that you wish to expose
  4. Edit web-app/WEB-INF/flex-servlet.xml (created when you installed the plugin): uncomment the context:component-scan element and set the base-package corresponding to your service class
  5. Make sure your exposed service methods don’t use Groovy classes, either as argument or return types. This is a known limitation I’m still working on, but if there are some Groovy classes here, Flash Builder doesn’t manage to generate ActionScript counterparts.
  6. Run your Grails application using “grails run-war” instead of “grails run-app”. Once again this is a known limitation: Flash Builder BlazeDS data connection plugin relies on a classical web app layout and doesn’t understand Grails dynamic layout (that is until someone manages to create a Grails data connection wizard for Flash Builder 4)
  7. In Flash Builder 4 beta 2, create a new Flex project with a J2EE server. Here are what your parameters shoud look like, “conferenceguide” being the name of my Grails application and “sarbogast” being my home directory:

  8. Click “Data” menu, then “Connect to BlazeDS…”
  9. In the “Authentication required” dialog box that appears, check “no password required” box, and click OK
  10. You should see your service appear, and you can select it and click Finish.

  11. Your service should appear in the Data/Services view. You can then compose your user interface and drag and drop your service methods to the relevant components to connect them with your Grails backend.
  12. Don’t forget to configure a channelset on your service:
    <adminservice:AdminService id="adminService" fault="Alert.show(event.fault.faultString + '\n' + event.fault.faultDetail)" showBusyCursor="true">
    <adminservice:channelSet>
    <s:ChannelSet>
    <s:AMFChannel uri="http://localhost:8080/conferenceguide/messagebroker/amf"/>
    </s:ChannelSet>
    </adminservice:channelSet>
    </adminservice:AdminService>
    

And there you go. Special thanks to James Ward, whose screencasts really helped me get it right. Now the only thing that this plugin misses, beyond the 2 known limitations, is integration with Spring Security, but this is just a start.

Enjoy!

Here Comes Grails APNs Plugin

That’s it. I’ve released my first Grails plugin ever. Woooo! Champagne!

If you follow my Twitter feed, you’ve probably noticed that I’ve been playing a lot with Apple Push Notification service lately (APNs for friends). Indeed, ConferenceGuide still requires a data connection, which can be problematic on a lot of events because they’re usually abroad (and roaming fees are waaaaaay too expensive), and even when you do have a data connection, it’s usually pretty slow… at best. That’s probably why one of the most requested features for ConferenceGuide is Offline Mode.

But getting all the data directly from the server does have at least one advantage: you’re always up-to-date. And experience has shown that sh** happens: sometimes sessions are cancelled at the last minute, or a global sound mixer reboots out of nowhere, thus shifting all sessions by 15 minutes. Those of you who were at Devoxx last November know what I’m talking about. So I needed a way to combine the best of both worlds: being able to browse schedule and speaker information without a data connection, and still get updates whenever something changes and I can find a wifi hotspot or something.

The first part of the solution is the local database. The second part involves sending push notifications. The problem with the latter is that the API provided by Apple is pretty low-level and the documentation is rather scarce. And it’s understandable because they expose a service that should be usable by any server technology, whether it is Java, .Net, PHP, Rails, etc. Fortunately, Java has a huge community and a great Open Source spirit, so it wasn’t long before a few projects were created to build an abstraction layer on top of APNs API. The simplest and most documented one I found is java-apns by Mahmood Ali. But ConferenceGuide server is not plain Java. It’s Grails 1.1 (I haven’t taken the risk to migrate to 1.2 yet). So I wanted to ease the integration of java-apns into any Grails application. And voilà! Grails APNs Plugin.

Special thanks to Burt Beckwith for helping me get started, and Mahmood Ali for developing java-apns!

My Discoveries of the Year

logoEvery year, the main reason why I go to Devoxx is to discover new stuff. For me it’s all about technology watch. The internet and RSS feeds are my main tech watch instrument but there is one thing that is harder to get through RSS: feelings. Conferences like Devoxx are a unique opportunity, not only to see what’s happening but also to sense how the community is feeling about it, which is at least as important to anticipate on what’s going to be important.

Now you’ve certainly read here and there that there have been a lot of talks about Java EE6 and Closures in JDK 7. There sure were, and there was quite a lot of reactions to those. But frankly, I’m not interested in any of those. I’m not interested in Java EE6 because even though it finally leverages the concepts that have been pushed by the community for so long, the very fact that Sun has been so late in implementing them shows one thing to me: it’s not about them, it’s about us. Sun has been trying to partner with big companies around the JCP, to create a lot of business around those standards. And why were those standards so complex? Because there were so many companies involved in their elaboration? Or was there any interest from those companies to create technologies complicated enough to require a lot of consultants, and books, and trainings, and tools to make things easier? If the first option is true, then how did it happen that a gigantic community of individual software developers made it so that Spring, Hibernate and other Open Source technologies became de facto standards?

Which brings me to the second point I don’t really care about: closures in JDK 7. People have taken matters into their own hands. Other languages have appeared implementing some of the missing features of Java: Scala, Groovy, etc. Some other languages have been imported into the Java landscape, like Ruby and Python. I’ve been using Groovy myself for some time now, and I couldn’t be happier with it. Now Sun is coming after the war, but does it matter? What I see here is that it’s good to have a base language, a base platform. But as soon as you start extending it for purely mercantile reasons, or as soon as you start avoiding certain innovations because you’re afraid it might harm your business or the one of your partners, then things go messy. But once again, the good news is that software gives us power. We developers have the ability not only to decide which technology is better, but to build and promote our own technologies. And I think this is why our world is so dynamic and why things change so fast. What I see here is that languages matter less than our ability to create new ones, to solve more specific problems, to provide some more advanced features. And that strengthens my belief that Language-Oriented Programming is the next big step in the evolution of our technologies.

Now about the things I do care about. My discoveries.

kanbanMy first one is definitely Kanban. I’ve heard about it for quite some time. But I didn’t understand why people were already trying to push it forward, even though we are still fighting to push companies away from waterfall messes. It’s even more radical than Scrum and for that it’s very interesting because it gets closer to what software development really is. The key phrase that kept popping in my head during the 3-hour session about Kanban was “It’s going to take the time it’s going to take.” And that’s why it’s brilliant. Now that I understand Kanban a little better, I see Scrum as a compromise. We’ve taken some of the principles of Lean Manufacturing, we have dissolved them into trusted concepts like RUP’s iterative cycles. And for years, we have been trying to pour that cocktail into their mouth. And in doing that we forgot something important: if they don’t trust us, they will never drink the whole thing, all the more so as it looks weird with all those colors not really mixed together. The way I see it, Lean and Kanban are all about getting back to the basics, and relying on trust. We have to build trust first, we have to make them understand that at least some of us are not interested in building artificial business on top of poor practices. That at least some of us desperately want the software we build to have a real impact on their business. We have to show them our good will so that they let us do our job. And they have to understand that the more they trust us, the faster we will be, the more we will be able to solve other problems. Big software vendors and resource providers will not like that, because every new project comes with its own overhead, because their business thrives on poor practices, stupid methodologies and complex technologies. But once again, power is in our hands, it lies in collaboration, not in corporation.

My second discovery was Spring-Actionscript. Those guys really have a thing to do things in a clever way. Cairngorm, PureMVC, Swiz, they all impose some sort of a structure to your Flex applications, forcing you to surrender some great powers of Flex itself in the process. And here comes Spring-Actionscript, more like a toolbox than a real framework. It doesn’t impose anything. It just gives you all the tools you need, all the glue you miss, to make things fit together perfectly. Their asynchronous abstraction is just brilliant, their configuration options are complete, your code just looks better with it, simpler, more natural. I think that’s what I love most with Spring: not only does it create great technology, but it also instigates a whole pragmatic and elegant way of thinking into the minds of a whole generation of developers, thus encouraging the community to come up with their own technologies: Spring Actionscript used to be called the Prana Framework, developed independently by a Belgian guy who took inspiration in Spring for Java. That’s just awesome. I will definitely integrate Spring Actionscript in a couple of Spring/Flex projects. I think I will even update my todolist sample application with it. Stay tuned.

My third discovery is a couple of technologies to detect and prevent coding errors BEFORE they actually happen. I insist on “before” because of my previous post about TDD: unit tests are all about writing code to check that some other code you have already written (or not written yet) does its job. But to me, this is equivalent to the old prevention versus repression debate. TDD is just repression, and it’s tempting to go there only, because it’s always easier to catch the bad guys than trying to understand why they became bad in the first place. JSR-308 and its pluggable type checkers is all about strengthening the compiler so that it prevents more of the most frequent bugs like NullPointerExceptions. It allows us to make our code more expressive, to give the compiler more information about our intents so that we can prevent bugs from happening. Brilliant! Project Lombok also goes in that direction: it adds a couple of annotations and customizes the Java compiler in order to minimize the amount of boilerplate code we have to type. Once again, by doing so, it improves the expressiveness of the language, allowing us to say more things with less words, thus reducing the likeliness of ambiguities and errors. Awesome! Lombok and type checkers will definitely be part of a couple of projects too. The only thing that really made me uncomfortable with both of these presentations was this question: “Why the hell weren’t those techniques in Java 5 already?”

pomodoroMy fourth and last discovery was Pomodoro technique. Once again, heard of it before, but never dug into it. And then we had this guy with a strange Swedish accent in front of us, playing with dolls, showing us handwritten slides with simplistic drawings. And you could hear the disappointed reaction of a lot of people in the room: “sounds nice, but not applicable to me”. That was my first reaction too. Software development requires long slots of concentration because we need time to load the whole conceptual model of what we’re working on into our mind before being effective, and this implies some overhead. But then when someone asked this very question to the speaker, he answered something like “what if you are loading too much? what if limiting the amount of time you are going to spend on a given task forces you to load just the minimum you need to solve the matter at hand? what if it made you more productive?”. And it made me think: “hmmm… It’s worth a try.” So I will probably try that as well soon.

Overall, this edition of Devoxx was great! The first 2 days, I was somewhat afraid that it would be disappointing, because you could feel that everything was “cheaper”, that there were less sponsors, less schwag, less tempting hostesses. But then the most important part was preserved: amazing independent content and a great community spirit. Finally there was an interesting special guest this year: Twitter. Twitter was everywhere. People were tweeting live from the sessions, there was a projection board with all devoxx-related tweets in the hallway. I and a bunch of my colleagues were even using twitter to cover Devoxx live for our fellow Axenian java developers on our intranet. Twitter was really everywhere this year.

So thanks a lot to Axen for allowing me to go there. Thanks to Stephan and the BeJUG for putting it all together. Thanks to all the great speakers and to my colleagues. This was really a great edition and I can’t wait for the next one.

PS: All the talks will be available in the weeks to com on Parleys.com. So stay tuned.

My Ideal Grails Flex Plugin

I’ve been trying all day to figure out how to turn my todolist-grails application into a Grails plugin, but so far, I’ve hit walls in all directions. Plus, Tomas Lin pointed me to yet another unfinished trial at integrating Flex in Grails, another one trying to work with dpHibernate.

Now I think it’s time for me to step back for a while and think a little bit about what I would like this plugin to do:

  1. When I install it into my project, I want it to create a src/flex directory and copy a dummy MXML application file in it. I don’t think that putting MXML files somewhere under grails-app/views is very clean. I’d rather keep only GSP files there.
  2. I want it to add one servlet and one servlet mapping for the BlazeDS message broker dispatcher servlet. Now the first problem is that this servlet needs a Spring configuration file and I don’t know how to generate it, knowing that this configuration contains a component-scan element that needs to point to the base package of the project.
  3. I need the plugin to handle Spring Security integration when combined with Acegi plugin (this I haven’t even managed to make it work with todolist-grails application so far) and to use the authentication domain generated by Acegi plugin.
  4. I need it to automatically expose all services whose expose static array contains the string ‘amf’ or ‘blazeds’ (the same static variable used my remoting plugin
  5. I need the plugin to automatically recompile my Flex application whenever I run run-app, and when the server is running, whenever something changes under src/flex
  6. I need it to provide a generate-html-wrapper target to generate a html wrapper within web-app
  7. I need it to provide a target to automatically generate Actioscript DTO’s based on a configured package (using GraniteDS GAS generator). By the way, I don’t want to use dpHibernate because I don’t want to expose my Hibernate entities to my presentation layer anyway. I’d rather work with DTO’s, all the more so as Groovy makes it really simple to copy data from Hibernate entities to DTO’s and vice-versa.

If there is a Grails plugin expert out there, please help me make this come true. And if you have the same dreams, if you need this plugin like I do, please leave a comment.

Grails Flex Integration, version 1.0

Ever since I discovered Grails, I’ve never stopped looking for the best way to make it work with Flex (I guess for me, the search was NOT over). Why so? Simply because the less time we spend connecting components, mapping objects with the database and dealing with boilerplate code, the more time we have for building gorgeous user interfaces. As for usual web suspects like JSF, GWT, GSP and other HTML/JS-generators, they have never been the best solution for me.

So how do we get Grails and Flex to work together? Well, Grails uses Spring behind the scenes and it is maintained by SpringSource, who also happen to be behind Spring BlazeDS integration in partnership with Adobe. So everything seems to be there… but there’s a problem. The best way to integrate any technology with Grails is via a plugin. Unfortunately the Grails Flex plugin is very old (it does not use Spring BlazeDS integration, but an old custom workaround) and only experimental. There is also a GraniteDS plugin for Grails, but GraniteDS is an alternative to BlazeDS, so it’s not the mainstream way of doing things. And Graeme Rocher has started working on a Spring BlazeDS integration plugin based on the old Flex plugin, but it was never released. Hmmm…

I know, when you’re unhappy with an open source project, when you feel it’s missing something, the better way to help is to do it yourself and share it with the community. But the problem is, although I love using Grails, I’ve never developed a plugin for it before. And this Flex plugin doesn’t seem like an easy one to start with. That’s why I decided to do things differently.

A few months ago, I published an article about Spring, Hibernate, BlazeDS and Flex. This article was very popular, both on my blog and on Adobe Developer Network. But new versions of Maven, Flex and Flexmojos have been released since then, so the article is a little bit outdated now. So why not use this opportunity to do an update?

So here we go. In the following file, there is the full todolist-grails project, that you can also find on GitHub (this is my first Git project by the way). This first version is merely a proof-of-concept. It’s not a plugin, it’s a traditional Grails application with Flex infrastructure added to it.  And because I didn’t find a way to integrate Flex compiler with Grails yet, I’m still using IntelliJ Idea to build the Flex part. Still, I’m publishing it as it is because I hope people will help me improve it incrementally.

So if you can help me improve this project and create a Grails plugin out of it in order to automate Flex compilation, integrate Spring Security, generate DTO’s automatically, you’re more than welcome. Let’s get this thing rolling.