semi/signal

I missed webOS Developer Day, but I took a look at the presentation of the Enyo framework (video below). I like most of the bullet points: faster performance, hardware acceleration built-in, etc. However, one point that’s troubling me is the idea of using higher-level controls instead of divs. From the bit of code presented in the final demo, it looks like layout (and pretty much all UI stuff) will be done using JavaScript widgets, which are translated at some point into the appropriate HTML constructs. Obviously, widget-centered development isn’t a new concept (MFC, WinForms, Cocoa… sproutcore and such on the web) nor is it necessarily a bad one (getting something presentable up and running is easier), but there always seems to be a very real and very large loss of flexibility.

When a widget doesn’t look or function exactly how you need it to, and it becomes necessary to make a new one, development within the widget framework can range in difficulty from trivial to near-impossible. As I mentioned when I wrote about Adobe Air, HTML/CSS isn’t perfect, but it’s the most flexible layout and styling framework I’ve come across. Abstracting away that flexibility in favor of plug-and-play widgets makes me cringe… it’s a nice idea, it’s a very (object-oriented) developer-ish idea, but it usually comes with a pretty high cost.

From working with both HTML/CSS and WinForms extensively, I’d say the widget-centered framework model used for desktop apps shouldn’t be replicated for web development. In fact, it should be the other way around: the flexibility of a HTML/CSS-esque system should be brought to the desktop.

How this will play out for Enyo, I don’t know. I’m cautiously optimistic. Being a web framework, everything still boils down to HTML and CSS, but it remains to be seen what level of manipulation will be allowed or make sense (in terms of performance, coding difficultly, etc.) at that level.

I made a little app to get my feet wet with Adobe Air. progTools just packages together a few common functions I find myself using frequently. You can get it my clicking the install badge (one of the very cool aspects of Adobe Air) below.

(h/t to Peter Elst for the AIR Badge WordPress plugin)

What’s offered:

• Conversion to/from a Unix timestamp
• MD5 hash on a string
• MD5 hash on a file
• SHA1 hash on a string

Not too impressive, and only the MD5 file hash really utilizes a desktop feature of the Air framework, but it is somewhat useful and, at least in my case, I won’t end up going to Paj’s Home to use the javascript md5 implementation demo quite as often. Note, Paj’s MD5 library was used and I slightly modified core_md5() for the file hash to deal with hashing successive blocks. I’ll post the code soon.

I initially dismissed Air, back when it was Apollo, as I didn’t see the value in having yet another proprietary framework which didn’t really offer much beyond what was capable within a browser, aside from local file access. A few additions to the framework and a few realizations on my part have shifted my views:

• Air supports HTML/CSS for layout and styling. Looking into cross-platform GUI frameworks, I’ve played around with WinForms (cross platform with Mono), Qt, Gtk, and wxWidgets. I’ve been disappointed to various degrees with all of them. It hit me that the most flexible and powerful cross-platform layout and styling framework out there is the HTML/CSS combo. It’s not perfect (e.g. floats, vertical centering) but it’s pretty damn good.
• Support in Air 2 for sockets and interaction with native applications. This vastly opens the field for the types of applications possible with Air.
• Market support from Adobe. The Air Marketplace is perhaps not too impressive, but it’s a major step in the right direction for desktop apps. Both Microsoft and Apple have their own stores planned, but with the success of such catalogs on smartphones for years now, why did it take so long to figure it out?
• Install badges. They’re cool and important as they provide a bridge between the web and the desktop. Odd, but it seems Adobe more-so than Microsoft or Apple seems to understand the web-desktop relationship. Again, why is Adobe, a company that was fairly divorced from the desktop application space, the first to figure out that this was something important or at least the first to actually build it.

Now it’s not all sunshine and roses. Making an HTML/AJAX app in Air brings up a problem every AJAX developer has likely faced at some point. Javascript is slow… very slow. JavaScriptCore/Nitro, V8, Chakra, Tracemonkey… it doesn’t really matter (though performance improvements are being made), once your volume of data grows you’ll cringe at how slow things become. Coming from C++, C#, or even PHP, it’s painful to witness. In progTools a file only a few megabytes large will noticeably stall the application (I didn’t do the call asynchronously, but that’s besides the point). ActionScript is perhaps better and interop to a native executable could also alleviate the issue, but ultimately I’d simply like a faster JavaScript engine.

A second issue, relevant but not specific to Adobe Air, is code signing; you’ll notice the scary warning when installing progTools. Code signing is bullshit. Expensive bullshit. Yet, every platform developer is requiring it due to some misguided attempt at security. If you want to install progTools, the chain of trust is between me » this web server » you. Sticking a certificate authority in this chain is nonsense – a typical user will not know the CA and cannot establish any level of trust with some random, corporate CA.

Coding signing simply punishes small developers and establishes a new industry to leech from our wallets. In addition, as this user on StackOverflow asserts, it may well hamper the success of Air:

When you visit a site that lets you download an AIR app, it pops up big red screaming warnings about the imminent trashing of your computer, the theft of your identity and a life of torment[1]. Unless, of course, all the bedroom programmers decide to cough up the ongoing cost of certification.

User encouragement FAIL. Hobby developer encouragement FAIL. Technophobe terrorficiation avoidance FAIL.

I love AIR, but I don’t know what they were thinking with the installer. Laywers’ office moved closer to the developers’ over at HQ or something?

Anyways, I’m done ranting. I’ll eventually suck it up and get a certificate as I’m powerless to do anything else.

As for Air, I’ve just scratched the surface, but I’m impressed.

oh, and if you’d like to see something added to progTools, just let me know.

These properties apply to scrollbar controls in WinForms, but the concepts are pretty universal:

• SmallChange is the change in value that occurs when you click on a scrollbar’s arrows
• LargeChange is the change in value that occurs when you click on a scrollbar’s track

I had some vague ideas on how to set these values, but this MSDN entry confirmed by suspicions that the values should be set relative to size of the container and not the size of the content.

User interface guidelines suggest that the SmallChange and LargeChange properties are set relative to the size of the view that the user sees, not to the total size including the unseen part. For example, if you have a picture box with scroll bars displaying a large image, the SmallChange and LargeChange properties should be set relative to the size of the picture box, not to the size of the image.

A while back I wrote about 2 applications, The KMPlayer and JCreator not behaving well when attempting to run both concurrently (see post).

Now, I have an incredibly weird situation on my system. KMPlayer and JCreator don’t play nice together. If they’re both open, some JCreator panels and menus are suddenly blank and don’t refresh and the side tabs panel is transparent, showing thru to the desktop. As for KMPlayer, I can’t open anything, clicking play (which plays the last file opened when nothing else has been loaded) does nothing, and certain items are mysteriously missing from the context menu. This hasn’t been a big deal for me, and I still use both JCreator and KMPlayer, but it would be nice if they worked together. Also, I have to wonder, what is the common component causing the conflict here, what would a media player and a java IDE both be using or trying to access concurrently? (assuming there is a conflict for a common component, which I suspect might be the issue here)

My suspicion was wrong, it was not a conflict between the applications or a common component, it was the system running out of User objects. In Winforms (and I suspect most other GUI toolkits as well) any GUI control or window will consume at least 1 user object (more complex controls, with multiple sub-components will consume more User objects), and when the system or process hits the limit (65,536 for the user session, 200 – 18,000 per-process; default is 10,000 on Windows XP), creation of new User objects will fail, even if the system has enough memory to support whatever it is that’s being created. On the .NET Framework, you’ll notice this if you get an exception that looks similar to the following,

System.ComponentModel.Win32Exception: Error creating window handle. at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at System.Windows.Forms.Control.CreateHandle() at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at System.Windows.Forms.Control.CreateControl()

I’m still puzzled as to why there simply isn’t a limit based on available memory, but I haven’t been able to find a whole lot written on User objects in general much less details on why they exist.