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.
Every 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.
My 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?”
My 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.
In the previous post, I tried to think of the business constraints that intervene in the choices of a software architect. In this one, I’ll take a feww shots at guessing which technologies are important nowadays to build software solutions for these constraints.
There are so many technologies out there that I will not risk myself in designing some sort of female magazine test like “tell me about your application, I’ll tell you what technologies you should use”. That’s a very exciting part of what I perceive as what is the job of a software architect: finding the right combination of tools and techniques for a specific business context in order to develophigh-quality, high-value and robust software for customers.
That said, there are a few important areas that seem very important to explore or even master in this world, and more specifically in this new economy we’re facing.
Java is a very mature and popular technology, so much so that many people have predicted its death times and times again. But in my view, it’s very much alive, especially with recent developments that made Java development much more productive. Of course, SpringSource-originated frameworks like Spring and its galaxy have changed the enterprise Java environment for a long time.
But even more recently, inspiration has come from the “casual programmer” side with Ruby on Rails and Python/Django yielding even more interesting developments like Groovy and Grails that combine the flexibility of a dynamic language with the incredible power and richness of the Java platform.
In my opinion, Groovy/Grails are about to rejuvenate enterprise development in an incredible way.
There has been a lot of marketing fuzz a few months ago about something called Service-Oriented Architecture. Unfortunately, although it was based on common sense, marketers and tool vendors completely killed the concept in the egg, but still, some important aspects have emerged and remain limitations of the most popular technology platforms. One of them is the importance of modularity: the ability to change one part of a system without touching anything else, whether it is to adapt them or to restart them.
OSGi (Open Service Gateway initiative) is a standard that has made a remarkable progression on the server side in the past few months, and with its massive adoption by major vendors, it’s definitely going to be something to watch.
RIA-enabling technologies compose a very competive landscape: Adobe Flex, Microsoft Silverlight, Sun JavaFX, and even more niche technologies like OpenLaszlo, Curl. And I’m not even considering all those Javascript frameworks and AJAX-generating techniques that I personally don’t see as viable alternatives in an enterprise environment.
My technology of choice is definitely Adobe Flex: it’s open (and it’s even become one of the most impressive examples of Open Source development lately), it’s robust, it’s server-agnostic (it works with Java, .Net, PHP, Python, what have you), it offers desktop integration capabilities, making it possible to cover many of the use cases mentioned above, and it’s very elegant by design. More importantly it was one of the first RIA technologies out there, which makes it both very mature AND very popular.
Mobile development has always been a hobby. Taking useful applications with you is an old fantasy. For a long time, it’s been so poor that it was difficult to turn this hobby of mine into a professional activity. That was until I came in touch with iPhone SDK development, which really blew me away. For the first time we have some great mobile hardware with unique usability capabilities, and we have the software development platform to use those capabilities like never before. And it’s going to be even better with the release of iPhone OS 3.0.
Of course, it’s about to become a very competitive area too, with the release of Palm WebOS, Google Android and Nokia Qt. But for now, the iPhone SDK is by far the most advanced native mobile development option.
The purpose of this series is double:
1. try to show why software in general, and software architecture in particular are such exciting fields
2. wake up people who tend to have only one single hammer in their toolbox
Now if in addition to that, it can create a debate, then I have a few questions for you guys (and hopefully gals :oP) So, what technologies do you think are important to know in the current and future software world?
In the previous post in this series, I tried to enumerate the most frequent kinds of applications. The question I’m going to ask myself here is what are the constraints that intervene in choosing the right paradigm and the correponding technologies to implement it.
Before we start answering that question, let’s just be clear with something. We live in a world where there are plenty of free and Open Source libraries and frameworks and tools of all kinds. It doesn’t mean that free is always good, but at least it’s an option, and if you have a commercial option that can add some value somewhere, then go for it, it’ll be worth it. So I won’t consider tooling cost as a parameter here.
Whenever you hear your customer say “I need it to handle several million transactions per second”or “I quickly want to make decisions based on thousands and thousands of records”, you know that you will have to think about performance. There can be several kinds of performance: memory consumption, CPU cycles, disk space, network bandwidth, hardware cost, etc. And all those metrics very often play together, which means that any change to one of these metrics has an impact on all of the others. For instance, it’s very common that you have to increase memory consumption to optimize CPU or disk access (caching).
Another important characteristics of performance is that optimization requires you to dig deeper into low-level details, because most of the performance is lost when abstracting machine constructs to be closer to human users. That’s why optimizing performance requires more work than doing things naively, and it’s very important to weigh the benefits of this work compared to the cost.
Moreover, it’s sometimes tempting to think of performance very early on and to focus on that more than the business value the application is supposed to create. But experience proves that you can quickly end up with very fast systems that don’t do what they are supposed to do because the closer you are to the machine, the harder it is to develop on it or maintain it. That’s why Donald Knuth said:
We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.
Nowadays, it seems like all applications are meant to be web applications, all the more so with the recent fashion for cloud-based applications that attempt to “webify” traditionally desktop-based apps like word processors, worksheets, and so on. And there has been so much effort spent in web apps in the past 10 years or so, that everyone knows about the technologies to build them. Yet it’s always important to ask yourself a few questions: will the application be accessible to the general public? Will it be extranet or intranet? How many users are likely to access the application at the same time? Are potential end users ALWAYS online? What would be the impact of the browser crashing in the middle of a session?
Sometimes, having to think about data access concurrency, network bandwidth or security is a useless hurdle that you can avoid just by developing a desktop application.
What if your application doesn’t need a complex user interface but requires just a few parameters to do its job? What if, on the other hand, it needs to be easily automated and integrated into a batch processing system? When you face such a business context, it’s important to consider the option of a CLI app, because then it can also be easier to integrate with other kernel system apps through scripting.
Whenever you hear your customer say words like “data analysis”, “system check” or “automatic synchronization”, you’d better think twice about your web app idea.
At the other hand of the data analysis pipeline, there is data input. And the more data there is to input, the higher the risk of rejection of the application by end users. And since end users generally wait a long time to get theirs hands on the application, this rejection traditionally happens very late in the development process. Combine that with the fact that people who ask for the application are not the ones using it, and the very special mindset of developers and you have all the chance in the world to miss your target and have the project fail before it reaches the finish line.
Of course, technology is not the primary solution to this problem. The first thing is to consider end users, consult them, talk with them, even if the business owner doesn’t think it’s useful. Then of course, methodology goes a long in putting the application into end users hands as soon and often as possible. But as soon as you realize the specificity of what users are expecting, you understand that you need a technology that gives you all the freedom to implement very complex use cases, without forgetting about the conventions and paradigms that people are used to.
Web apps have another big drawback in addition to ergonomic limitations, which is desktop integration. This issue comes from the security model of the web. Because it’s so easy to access a web application, because you don’t have anything to install and because the application is directly connected, it also creates a huge opportunity for malicious use. Which is why web apps usually work in what is called a sandbox: network access is limited to the originating domain (unless specified otherwise), no direct access to the file system is allowed, no native API access to things like system tray icons, drag and drop and so on.
And if your application has tom import or export very big files, or notify the user on a regular basis, those limitations can be a killer. There are some technologies now that create some sort of a bridge between a runtime plugin in your browser and a runtime app on your machine, but portability of this bridge across systems and across browsers is sometimes limited.
How stable are the business rules you’re asking me to implement? How sure do you know what you expect from this application? If your customer answers “not very” to any of these questions, you might think twice about using this low-level highly-optimized programming language. Because if it takes you weeks to implement any change or new feature, your application might quickly end very far away from the business value is was supposed to create.
Fortunately, with the maturity of web application development, there has been a lot of very interesting developments in the area of development productivity lately. Development tools like integrated development environments certainly go a long way in making developers more productive, but when this concern is dealt with at the programming language level, it’s even better.
Whatever technologies you plan to use, you definitely must consider the constraint of resources. There are so many techniques out there that it’s impossible for everyone to know all of them. Some of those technologies are very mature and popular, thus making it easier to find people to maintain and evolve your application on the long term. But the more mature the less innovative they often are. So finding the ideal compromise between the benefits of innovation versus the cost of resources to maintain your application is very important. Thus is might require some insight and technology watch in order to anticipate which of these innovative techniques will grow fast and be there for a long time.
And if you really need one of these innovative technologies that is not very popular yet, then don’t forget to include training costs in your plan. Last but not least, don’t forget to consider company-wide policies: IT architecture departments can create substantial impediments on your way, which might lead you to weigh in the cost of those impediments.
Beyond people able to maintain it, there is another thing that is very important for the longevity of your application: the intrinsic software quality assets of the technologies that you use. Testability, decoupling, Domain Specific Language support, portability, internationalization support, integration capabilities with other technologies and platforms, extensibility, modularity. All those characteristics can be very important to consider if your application is supposed to stay there for more than 5 years and evolve with the business at hand.
A lot of money is spent and sometimes wasted in reegineering entire applications just to keep up with current technologies or new business constraints, so much so that choosing robust and evolutive techniques can greatly reduce the long term ownership cost of the application.
In the final issue, I’ll risk myself into making some predictions about the technologies that seem very important in order to implement applications with that kind of constraints. But before I do that, do you see other business constraints that might be important to consider before choosing the best tools for the job?
What I really like about being a software artist is the richness of tools and techniques you have at your disposal. And the more tools you have, the harder it is to use the right ones, the more tempting it is to limit yourself to a few of them. But to me it’s like analogic versus digital DJing: given that your ultimate purpose is to create sounds that make people move, why limit yourself to sync-and-scratch when you can have effects, loops, samples and a virtually unlimited library of tracks?
But I’m sort of missing my point here. Let’s get back to software. I’ve recently come to work on a new project that has been in the works for almost 2 years. For 2 years, wanna-be software developers have tried to solve a very difficult problem with very usual tools. It’s like Maslow said:
When you know how to use a hammer, everything starts to look like a nail.
Well, guess what! Everything is NOT a nail. And I’m gonna try to go over the reasons why in this post.
…and each member of the family has its own personality.
The most popular right now is certainly web applications. And by web applications, I mean traditional ones. HTML, CSS, throw is a little bit of Javascript, and maybe generate all of that with some server-side scripting like PHP, Python, JSF or whatever. Heavy load on the server, but very lightweight on the client. The interface is somehow poor because it relies heavily on technologies that were designed for documents gathered in websites, rather than for full-blown applications, with all the interactivity that it implies. Yes, some progress has been made in the past few years with all this AJAX stuff, but bear with me, this all seems like tinkering to me.
The mirror opposite of lightweight clients are certainly fat clients, aka desktop applications. Those applications are based on a composition of graphical widgets the user interacts with, throwing events around and interacting with the operating system. Contrary to their web counterpart, they usually require quite a procedure for deployment and maintenance, because they are physically running on the user’s machine and only check in with the server if they need to. But damn they’re fast.
More recently, a new compromise solution has shown up, offering the best of both worlds: the great ergonomy of desktop clients combined with the ease of deployment and maintenance of web clients. That’s what marketing guys have lovingly called Rich Internet Applications. Now behind this lovely RIA thing, there are a few technologies that make it a lot easier to write rich user interfaces that run within the confines of a web browser. But still, those have limitations compared to their pure desktop brethren: poor integration with the operating system, security constraints all over the place, heavily rely on server-side business code.
Now if Rich Internet Applications are web applications that solve the ergonomy problem, there is of course the other side of the compromise: desktop applications that solve the deployment and maintainability issues. Those are sometimes called smart clients: local database, offline mode, online synchronization, automatic updates, easy one-click installation.
Even though, those seem to fulfill the family picture, there are a few weird cousins out there that are good to be known. Command-Line Interface (CLI) applications have poor to no user interface at all. Their main purpose is to be run on the command-line by some geeky system administrator somewhere, or to be part of batch scripts running automatically every night. Very useful for maintenance apps, and for all long tasks like data analysis or system checks.
And of course there are mobile applications and all kinds of embedded systems. The user interface simply cannot be rich here, because the display is so small, and the computing resources are so limited. Small memory, small keyboard. The iPhone is certainly changing the landscape here, but you still have to manage memory!
Don’t forget extension apps, like SAP modules, CMS plugins, MS Access applications. Those are applications of their own. Usually highly specialized but very fast to develop for simple use cases, to get things done quickly.
Finally, even though, they’re less and less popular, there are still many mainframe applications out there. Now I won’t go into much details here because I’ve never set foot on that ground. But it certainly doesn’t harm to remember that it exists.
Now there certainly are a few other kinds of software applications out there that I didn’t think of, but you get my point. There are a lot of different tools out there, and very different techniques to use those tools in order to create software solutions to very different problems. And what makes those problems so different, you might ask. Well, it’s all about the business context. In the second part of this series, I’ll focus on the characteristics of a business environment can influence the tools you choose to implement the solution to a problem.
But before we get there, do you see other kinds of applications that I forgot to mention?
