what do I know

With my latest employer, I have taken the big dive into the .NET world. I’ve spent most of my career working with ColdFusion, Java, PHP, Flex and dabbled a little bit in the Ruby/Rails and Groovy/Grails world in addition to the obvious set of web technologies and standards that span all of these application languages. My limited experience with .NET was through some undergraduate and graduate work I did with C# as well as helping (if you can call it that) with an ASP.NET a long time ago with a colleague of mine. I am a application developer; even though I dabble in lots of different areas, the bulk of my knowledge is building applications in a corporate IT environment. I focus on implementing business requirements and managing technical concerns as it relates to the software development process. I’ve had jobs in the past associated with business and management roles but at the core I am a plain and simple application developer. As I’ve been getting my hands dirty in .NET over the last few months I figured I’d share some of my initial impressions. Please keep in mind, I may be looking at a lot of things in a very naive light, so read what I have as my opinion, ignorant or not.

With context out of the way, I have to say that so far working with .NET hasn’t been a negative experience. There is the whole you’re stuck with Windows thing, but since I’m in fully entrenched in the MS world now, I’ve been able to get past it. There have definitely been some nuances to get used to, but nothing extremely difficult to overcome. Here are a few comments on some of the things I’ve run into thus far:

• Namespaces in C# aren’t constrained by the file system with respect to partitioning your code. Initially this seemed like a nice decoupling, but I’ve found myself forming more of a dependency on tools to navigate my classes hierarchy rather than just looking into a folder.
• There is no notion of a shared class path as there is in Java. If you want to get a hold of an assembly to use in your application you’ve got to find it and pull it in. I think there is a configuration option on an assembly that you can use to help, but I haven’t had any experience using it.
• Assemblies are pretty nice build artifacts. Versioning is addressed out of the box and integrated with the .NET framework. I’m not sure how they stack up against something like OSGI, but I’m enjoying having them around.
• Everyone says the implementation for generics is better in C# than Java, but as an application developer I don’t notice a difference except that I’ve been told I can use reflection on them in C#. C# also seems to have made a much larger use of them in their core over Java. It seems like stronger typing is a very important practice in the C# world than in my experience with the Java world, but that is probably biased based on how I’ve used Java.
• There appears to be a very balanced view on uses for metadata (attributes) in .NET. Annotations in the Java world were a great addition to the language, but sometimes their use comes off as abuse; look at a JUnit 4 test suite class for a great example.
• There are lots of accepted libraries available that are direct ports from the Java community such as NUnit, NAnt, Spring.NET, CruiseControl.NET, NDocs, log4net, etc. Getting comfortable with these libraries was pretty easy since I’d had experience with the Java equivalents.
• The help systems in .NET leave much to be desired and make me long for Javadocs, Livedocs, RDoc, or anything else. I find myself clicking through a class definitions on MSDN and after two or three links I can finally get to a list of “members” that belong to a class, only to click another link to load another page to see more about the details of that “member”. I have yet to find any easily usable API documentation.
• .NET has a solid component model available out of the box. WCF is a really simple and tight implementation of a component architecture. Service-orientation is a focus with an emphasis on abstracting away protocols, execution environments, and exposing metadata for a more contractual usage. It has the feel of being an API built around WSDL 2 and many of the WS-* standards, but it goes by many of the concepts, although not by name, identified in Patterns of Enterprise Integration. It’s compatible with synchronous and asynchronous operations and did I mention simple to use? I hope to do some posting about it later.
• Getting used to assimilating applications into the bowels of the OS seems to be core to the .NET mentality. This is probably just a matter of perspective for the developer, but based on the examples I’ve seen thus far, the user folder, the registry, and Windows\system32 folder are popular hang outs for lots of applications. I’ve been met by quite a looks of confusion when I mention deploying applications without the use of some type of installer. There is a lot of power that you get from this tight coupling with the OS I’ve been told. Unlike my previous shops, writing cross-platform applications doesn’t seem to be a priority for .NET developers, so tight coupling it is.
• It took me listening to the episode of SER with Anders Hejlsberg to understand better it, but it appears to be that developing in .NET is meant to be an IDE integrated experience via Visual Studio. Regardless of the aspect of development I’ve worked with in .NET thus far, the development experience has been fairly consistent. There is always some visual representation of the code available (where applicable) and a debugger is always around and working no matter the context (desktop, web, etc.). At first it was so simple that I felt like I was missing something, but from what I have read and heard, as much work goes into VS as does the .NET framework, if not more. If anyone has used Netbeans for Java web development, it’s a very similar experience in terms of its integration with the environment.
• I’ve always seen code insight as a supplemental thing, relying on documentation for the majority of my work, but wow, code insight (intellisense) seems to be the major crutch on which a lot of .NET developers place themselves within VS. What’s weird is that I don’t notice anything different than what you’ll experience when working with Eclipse and Java, in fact, the code insight seems to be limited to code only. I have yet to run into a situation where the IDE makes a suggestion on how something could be written or changed as IntelliJ does for Java. I will admit though, maybe I’m missing something.
• The visual editors in VS seemed to get abused by .NET developers. I say abuse because quite a few .NET developers I’ve encountered can’t talk to me about their code in any other context but how they dragged-and-dropped controls onto a screen and edited properties. Since I don’t know the in’s and out’s of the tools quite yet, having a conversation is tough. I try to communicate in terms of language agnostic principles and patterns but most of the time all I get are blank stares and judgmental comments about how I am over complicating things.
• MS alternatives exist in terms of the IDE and runtime, but they don’t seem to be popular at all. I really like SharpDevelop as an alternative to Visual Studio. It’s clean, easy to use, and integrates with a lot of OSS packages out of the box. Mono is available as a Linux-based .NET runtime that has a lot of .NET developers excited because of its potential to allow them to code for the Mac. I don’t know any Mac owners that have Mono installed however, so I don’t know if it’s really a viable cross-platform solution.
• I have some thoughts on ASP.NET web forms that I want to share, but I’ll save that for my next post.
• The developer community has always been important to me and I feel it’s always important to remain active in the community in some capacity. As I’ve begun attending the local .NET user group meetings, I don’t see a lot of topics that are not MS centric. There is no question that MS drives the releases of the .NET framework, but there have been lots of innovations coming out of the community that deserve attention. It feels like there are only a small minority of developers that actually utilize these contributions locally. I have yet to see any presentations on the various unit testing tools, build tools, ORM, IoC, etc. that have come out of this space. I do envy the direct support that MS has for its user groups, but I wonder if my expectations are too high.

In any case, so far the learning curve with .NET hasn’t been very steep and when I do get to code I feel fairly productive. I should be posting in the next few days on my thoughts about ASP.NET web forms so I’m sure that will get me flamed, but it’s a major part of the puzzle I’m having to work with that I feel needs some attention. Until next time.

Ok, I need help. I’ve been able to discover the coolness that is getQualifiedClassName() and getDefinitionByName() and describeType() when it comes to working with introspection/reflection in ActionScript 3. I am stuck however. I want to get a hold of all the class names available in the compiled Flash movie at runtime. I’m writing a library that will look for custom metadata on classes and associate functionality with the classes (or possibly objects) if they are annotated in a specific way. Right now, short of asking for a list of those classes from the developer, I don’t know of a way to build a bootstrap function/class that will introspection into the Flash movie and get me a list of them. I was thinking maybe if I could find a way to programmatically access the manifest file that would work, but again I can’t find a way to do that.

Does anyone know how to do this or am I doomed to introspecting on objects and programmer declared references rather than classes?

UPDATE: I found a feature request in the Flex 3 JIRA database. Basically it’s not in Flex yet, nor is it supported by the Flash movie, but 4 people have voted for the feature thus far. That being said, please vote for this feature so we can get one of the final pieces to reflection built into Flex. BTW - If anyone wants questions answered with regards to Flex, check out the flexcoders mailing list over on Yahoo. Everyone probably knows about it but I’m slow.

Peter Armstrong, author of Flexible Rails, gave this presentation which focussed on how Flex and AIR can consume REST’ful resources. Peter unfortunately had a hard drive crash about an hour before his presentation so needless to say his presentation didn’t go as planned. Although he didn’t really have any slides (because they were all destroyed) he was able to borrow the laptop of a fellow conference go’er and show us some code examples.

The code examples were geared towards introducing MXML and Actionscript to Rails developers. I feel pretty comfortable with both, but it’s always good to see different approaches to coding in Flex, especially code using HTTPService since I spend more time using RemoteObjects. I would have liked to seen, if only mentioned, the topic of component development (visual and non-visual) and data binding, but I can understand why it was omitted since most Rails developers aren’t familiar with UI practices other than your standard web stack.

Towards the end of the presentation, Peter revealed Ruboss, a Flex framework built specifically for consuming REST’ful resources. Ruboss uses a controller to expose an Actionscript interface to translate CRUD operations to their REST’ful equivalents. He said he’s going to be releasing it over the next few weeks under his new company, so watch Ruboss.com for more details.

We’ve asked Peter to give a Connect presentation at an Adogo meeting later this year on Flex/AIR and Rails. The Orlando community can definitely benefit from Peter’s work with Flex/REST and we hope to pimp that to its fullest … j/k Peter, keep up the great work.

Recently, I've been interested in examining the features of non-visual components as it applies to Flex. I don't hear them talked about a lot (at least in the small part of the blog-o-sphere that I read), but I think there are some uses for these types of components that could really catch on in the community. I've tried to put together a sample application to show an example of some of the ideas I'm playing with in my head.

So the big place where I see non-visual components having a use is when attempting to bridge the stateless and stateful portions of a Flex application, mainly in the area of remote services. When I design a web service or remote object to be used by Flex, I typically build it in Java (or ColdFusion) and I design the service such that its methods operate in a stateless fashion. For example, when I call a method on my service, I don't expect previous calls to that method to influence the results of my current call; at least from the perspective of the caller. Additionally, I have the expectation that more information may be required when calling the method since the remote object receiving the call has no context in which to interpret the method call besides the method itself. Now I'm know an argument can be made about whether something truly is stateless or not, but that's not the goal of this post. Let's work with this ad hoc definition of stateless for now.

Flex provides us with a very simple, global means to get a hold of these services: RemoteObject, WebService, HttpService; there are other means by which to connect to remote services, but for now let's take the simple example of stateless RPC-based services. Typically in my Flex applications, I want to emulate a synchronous call from the application to the service (using something that implements IResponder or mapping the result/fault methods manually). Ideally I should have a class abstracting these calls to improve cohesion in the application; frameworks like to use command, delegate, or proxy classes, for example. During the emulation of this synchronous call I usually have my result/fault handler call out to a method on a class to change the state of an object (e.g. - setting values on the ModelLocator in Cairngorm), consequently firing propertyChanged events and/or custom events to update visual components via data binding.

All that being said, there are a couple of things with this approach that I want to address. First, I'm making the assumption that the class which abstracts the interactions with my service should also remain stateless. No where in the creation of the object am I changing its state so that the behaviors associated with the object may have a different context when executed. Second, I'm making the assumption that the behavior of this abstracting class must be separate from the data it uses. Propagating a change in an object's state via events is the back-bone of Flex data-binding. Not only that, but data binding is very simple to use and code, why shouldn't this simplicity be available in the ActionScript class abstracting the call to the remote service?

So that's enough conceptualizing for now, let's look at some example code. Please note the entire working example can be found at this location.

In this example, we have a very simple phone directory application. A SearchView exists which takes input from the user and announces a custom event (SearchEvent) passing that user input as its payload (i.e. - SearchCriteria). This event is handled by the Application class which in turn calls the find() method on an instance of SearchComponent. SearchComponent is a non-visual component which uses data-binding to propagate changes from the stateless world into my stateful Flex application. The code for SearchComoponent can be found below:

There a few things to note about this component for the purpose of this example:

• A method on a remote service/object is not actually being called, I'm using an XML document to simulate that process.
• I am not actually emulating a synchronous call, I'm allowing the current thread to block on the method call. If I were to emulate the synchronous call, I would suggest using anonymous functions as the result and fault handlers for the remote service/object. The code in this example would be short and not warrant a named method mapping (this is done a lot in JavaScript when registering event handlers).
• Yes, my coding style kinda sucks, get over it.

Now when the find() method is called it does not return anything, instead it updates the component's internal state via the employees property which then fires a propertyChanged event which is handled by ResultsView to populate a datagrid. Additionally, notice that when the object is constructed it makes a call to fetch location and department information to which controls in the SearchView are bound and updated when construction is complete. These values from these controls are used to filter the search performed by the user.

Going back to the conceptual, there are a few questions that come to mind:

1. Aren't components supposed to be reusable? - From my POV, it feels like Flex has already done a great job of handling re-use through the RemoteObject, HttpService, and WebService classes. It seems that if re-usability is needed it would be at the service rather than the non-visual component. The non-visual component in my example is literally acting as a perspective for its service, or what potentially could be a group of services. Right now, however, I'm not sure if there are huge performance issues that may result from having multiple component perspectives for a single or series of services. I would assume for RemoteObject it may not be as big as a hit as it would be for a web service. Maybe this would be based on the remoting implementation you choose (i.e. - LCDS, BlazeDS, WebORB, Granite Data Services, etc).
2. Aren't you just causing side-effects on objects? - In my opinion, it's not doing anything different than what Flex is doing with its visual components. In fact, what I think justifies this particular approach is the fact that you have the ability to notify anyone watching the object when its state has changed; I've always considered side effects as changes in state that I potentially didn't know about as the caller. The Flash movie instance is stateful; why not take advantage of this environment to add state to the classes abstracting our services? I'm building these non-visual components to satisfy the needs of my application, so I will know how they should behave and can to document that formally based on the constructs of the language. Now, if you ask me if this approach should be used for building an API-like interface to a set of remote services, then I would have to say no. The implementer of an API doesn't know how their code will be used in the context of an application, consequently keeping these components as stateless as possible is to the benefit of the API developer; context is limited to the execution of a method call. I think the Twitter API for Flash Developers is a great example of this.
3. Where do I put all of these non-visual components? - This question I believe involves much more conversation about the implementation of these non-visual components. The example application is extremely simple and does not represent the issue of how to handle event propagation. In the example, all events are being propagated to the Application class and emulating a sort of global event system similar to those that I've seen in Flex frameworks with which I've worked. In fact, this is how easyMVC handles its event registration in the ControllerFactory; a ControllerEvent with a user provided type is registered on the Application and no matter where the event is dispatched, it's told to bubble to the Application to be handled by a mapped method in a custom Controller class. I have to admit that I like this approach much better than Cairngorm and PureMVC's approach of building their own global event system. I know both camps have their own reasoning for why they've done it, but I don't think that what Adobe has provided is worth re-writing. On the other hand, does the hierarchical nature of MXML bind visual component layout and construction too close such that without global event systems we can't be productive as Flex developers? On a side note, data binding in practice isn't always the answer to our problems; how a component can take advantage of these non-visual components and still interact with the components it needs to is a mystery to me. This may come back to the nature of MXML as well.
4. Do I need a framework if I use this approach? - This is something I'm still trying to figure out. The biggest use of Flex frameworks I've found is a structured approach for making calls to remote services. I feel like frameworks have way too much boiler plate code and if this approach is practical, a good alternative may exist in place of adopting a framework. It seems to me like Flex frameworks have come from the mindset of the web world where stateless HTTP is king. We don't have to use the Front Page Controller pattern to build rich UI's; I think it's time to move on to different interpretations of the MVC pattern. I always find myself asking, did developers in the Java Swing world find themselves turning to a framework or were the constructs of Swing enough to be productive. If people were productive with Swing and it was a widget toolkit for AWT, why can't the same be true for Flex and Flash?

All this being said, this is just my latest idea. As you can tell, I still have a lot of unanswered questions. We are the process of implementing this approach on a much larger scale at work and hoping to solve the questions listed above. I'm always interested in feedback, so please rip this to shreds. I am far from experienced in this arena and am always open to what others have to say despite what some may think.

NOTE: For those who are interested, I began along this line of thinking based of the latest buzz-worthy topics in the programming community. It interested me as to how OSGI implemented their component architecture in Java w/o some language level support (e.g. - formal properties) and why it so popular. I was also intrigued by a proposal put together by Joe Noxel, from the Java Posse, regarding additions to Java for some of the language level elements already present in Flex. Additionally, SOA has come into debate by some of the more experienced professionals in software engineering and SCA (see Apache Tuscany as an example) has been identified as a potentially better alternative. So all this talk, combined with the little amount of component programming I've done with COM+ and .NET, made me wonder. If there is such a huge draw towards component-oriented design is there anything in Flex that we can do to take advantage of these practices? Does having formal properties and support for events as it presents itself in Flex aid developers with the tools necessary to utilize component-oriented design? Is one of those areas specifically the perspective of bridging the gap from the stateful component to the stateless service? Now I know a component has a much richer definition than I'm limiting it to, but this is just the point. To what extent can we, and should we, use components within Flex?