Tim Anderson’s ITWriting

Bart Czernicki has a detailed post showing how Silverlight 2.0’s multithreading can improve performance. He took my counting primes code and  adapted it for parallel processing. On my quad core system the results are impressive:

As you can see by squinting at the screen grab, the processing time went from 0.43 to 0.20 seconds.

Multithreading is getting a bad rap in some quarters, because it greatly complicated debugging. On the other hand, if you have an app which does some heavy duty calculations then performance benefits like this are worth a little pain.

Microsoft has announced that Silverlight will support the H.264 video standard “in a future version”, along with AAC for audio. H.264 is also used by Adobe Flash and has wide adoption across the industry; it’s likely that your HD video camera records to H.264, for example.

Good news for Silverlight, though it may be a while before we see this rolled out, but surely bad news for VC-1, Microsoft’s preferred video format and part of the Windows Media family. Why would anyone not standardize on H.264 now?

I liked this post by Larry Dignan on the cloud computing buzzword and how meaningless it has become.

Writing on the subject recently, I was struck by the gulf between what some people mean – online apps like Google Apps and Gmail - and what others mean, on-demand utility computing such as that delivered by Amazon Elastic Compute Cloud or Flexiscale. These things have little in common.

Dignan has even more examples.

Should we abandon the term? Maybe, but I find it useful if only as shorthand for describing how the centre of gravity is shifting to the Internet.

Some services are more cloudy than others. Dignan refers to this Forrester report (though you’ll have to look at the blog post for the extracts, unless you want to buy it) which has a table of “six key characteristics.” I don’t agree with all of them; the business model, for example, is not an inherent part of cloud computing. I am interested in number two:

Accessible via Internet protocols from any computer

Any computer? OK, probably not the Atari ST which I have in the loft. Any computer with a web browser? What about requiring a “modern” web browser, is that OK? Java? Flash? Silverlight? A specific version of Java or Flash? What about when we need a runtime like Adobe AIR or Microsoft Live Mesh? What if it doesn’t run on Linux? Or on an Apple iPhone? What about when there is an offline component such as Google Gears? All these things narrow what is meant by “any computer”.

This is the old “rich versus reach” debate; it is still being played out. My point: cloud computing isn’t a boolean characteristic, but a continuum from very cloudy (NTP) to not cloudy at all (Microsoft Office).

I’ve written a short piece on XAML for the Register. Here’s a few things you might not have known about Microsoft’s Extensible Application Markup Language:

1. It is not just for WPF (Windows Presentation Foundation); it is also used as a language for Workflow Foundation (WF). Microsoft has hinted that we will see more XAML applications announced at the forthcoming PDC.

2. XAML doesn’t have to be XML – see the intro to the XAML Object Mapping Specification 2006, which says that “any physical representation may be used.”

3. XAML is a small core and distinct from XAML vocabularies. The huge WPF is a XAML vocabulary. WF is another vocabulary.

4. Although XAML is usually represented as XML, it is near-impossible to create an XML Schema to validate it usefully. Here’s where Microsoft explains why.

5. In Visual Studio 2005, a huge but imperfect .xsd schema file was used for validation and to drive IntelliSense (things like code completion) in the XAML editor. In Visual Studio 2008 Microsoft abandoned that idea and uses a language service instead.

6. The core idea behind XAML is to be a declarative language for .NET. WPF is merely an early application for XAML.

7. XPS, Microsoft’s fixed-layout language that competes (just about) with Adobe’s PDF, uses XAML that is a subset of WPF. This means that you can actually display XPS documents in Silverlight – there’s no need for a viewer, it is native Silverlight code.

8. When you compile a Silverlight application, the XAML stays as XAML, albeit bundled into a resource.

9. Silverlight allows you to write inline XAML within HTML.

10. XAML rhymes with Camel. Sorry, you knew that already. But did you know that CAML (Compiled Application Markup Language) is XAML compiled to MSIL (Microsoft Intermediate Language)? Microsoft tested this idea in pre-release versions of WPF, but apparently the performance benefits were disappointing and it was less compact than BAML (Binary Application Markup Language), a tokenized representation of XAML. Silverlight doesn’t bother with either: XAML is saved as a resource in a .NET DLL, and then zipped as part of the .XAP package by which a Silverlight application is delivered.

This was the conclusion of an EcmaScript meeting in Oslo last month. Specifically, as Brendan Eich explains, three features - packages, namespaces and early binding – were considered too heavyweight unsuitable for a browser scripting language. Here is Eich’s “Executive summary”:

The committee has resolved in favor of these tasks and conclusions:

1. Focus work on ES3.1 with full collaboration of all parties, and target two interoperable implementations by early next year.

2. Collaborate on the next step beyond ES3.1, which will include syntactic extensions but which will be more modest than ES4 in both semantic and syntactic innovation.

3. Some ES4 proposals have been deemed unsound for the Web, and are off the table for good: packages, namespaces and early binding. This conclusion is key to Harmony.

4. Other goals and ideas from ES4 are being rephrased to keep consensus in the committee; these include a notion of classes based on existing ES3 concepts combined with proposed ES3.1 extensions.

This means that the evolution of JavaScript is now on a new path, focused for now on a more modest enhancement to the language called EcmaScript 3.1.

Given how loudly Eich protested about EcmaScript 3.1 last October, it is a surprising turn of events. Was Eich convinced by the arguments of Microsoft and Yahoo in support of a more lightweight JavaScript?

What this means is that JavaScript 2.0 won’t happen as previously envisaged. John Resig:

… you can forget a lot of what you learned about ECMAScript 4, previously. Many of the complicated concepts contained in the language have been tossed. Instead there is a considerable amount of effort going in to making sure that new features will be easily duplicable through other means.

Eich and Resig are keen to stress that JavaScript will still be a highly capable language. Still, the obvious conclusion is that this will be good for plug-ins which support more powerful languages: Adobe Flash, Microsoft Silverlight, Sun Java or Java/FX. Personally I’m disappointed.

It is also presenting Adobe with a tricky problem, as it implemented much of an earlier specification for EcmaScript 4 in ActionScript 3. Rather than being a standard language, as Adobe had planned, it looks like this will now be more of an Adobe language. I doubt this will have much practical impact on developers.

PS Brendan Eich has commented below.

I’ve been working on a Silverlight tutorial involving reading an RSS feed. Silverlight has a SyndicationFeed class which is meant to make this easy – as Microsoft’s Scott Barnes enthuses here.

It is handy, but I discovered that the Quickstart Barnes refers to does not work in Silverlight 2 Beta 2. The Quickstart section on Silverlight.net needs some work. Even if you get to this Quickstart via the link for Silverlight 2 Beta 2 examples on this page, it is soon apparent that it is actually for Silverlight 2 Beta 1. Click the Run It button and you’ll see that it asks for the older runtime.

The code doesn’t work in Beta 2 either; and as so often with thread-y stuff, it’s not immediately clear what’s going wrong. I got a blank page and the following message in the Debug output window in Visual Studio:

A first chance exception of type ‘System.UnauthorizedAccessException’ occurred in mscorlib.dll

In situations like this I recommend breaking on all CLR exceptions (Debug – Exceptions – check the Thrown box for Common Language Runtime exceptions in Visual Studio). Run again; and this time Visual Studio stops on the line which updates a Silverlight TextBlock:

feedcontent.Text += "* " + item.Title.Text + Environment.NewLine

with the message “Invalid cross-thread access”:

Rooting about a bit, I found this post from Karen Corby on changes in Silverlight 2 Beta 2:

HttpWebRequest’s delegates are called on a new non-UI thread.

• Delegates were previously always called on the UI thread.
• You must invoke back on to the UI thread if the data you’re retrieving will be consumed by a UI element.
• For an example, see the updated networking post series (part one).

What this means is that you have two doses of asynchronous coding to think about if you use HttpWebRequest. First, the request itself; and second, in the code you write for the response handler if it needs to update the UI – which in most cases it will.

The example referenced by Corby shows a neat solution using a SynchronizationContext object, or you can use the Dispatcher class as explained by Wilco Bauwer here – he also draws attention to locking issues. See also Shawn Wildermuth’s post though note that CheckAccess is available despite what is said here.

This adds a significant dose of complexity to Silverlight coding. I’m not sure if any of this will change again in the final release.

I also noticed that VB coders are not well served by the Silverlight examples out there, which are overwhelmingly C#. Looks like this is the language of choice if you want an easy life.

The BBC’s streamed catch-up broadcasting, iPlayer, is about to be upgraded to the high-definition H.264 standard, according to this post, from the BBC’s Head of Digital Media Anthony Rose.

He says that the “Play high quality” option will be available “from this week”, though I couldn’t see any sign of it on a brief sampling of available content.

The question: where does this leave the download service, based on peer-to-peer file sharing? This is the thing that caused me considerable hassle this time last year, and which also drew criticism because it is Windows-only.

By contrast, the Flash-based embedded video seems to have performed as smoothly as Flash usually does.

When Flash streaming was introduced, the BBC said that the download option would remain for higher-quality viewing, but with H.264 Flash that argument has little force. It is still comforting to have a downloaded file, in case your Net connection fails or becomes congested, but other than that there is little advantage. My guess is that it will wither. Supporting both must be expensive.

It is unfortunate for Microsoft, whose technology is losing out to Adobe’s at the BBC, particularly since Silverlight would probably have worked nicely in this context. Unfortunately the old iPlayer is not Silverlight, but based on Windows Media Player, known to be hassle-prone as well as being single platform.

First, the patch removal tool, now officially called the “Visual Studio 2008 Service Pack Preparation Tool”.

Wait ages. Useless progress bar stuck at 50%. Wait some more.

Help – it’s asking for the Visual Studio DVD. Hey, at least it proves it is doing something. But where is it? Scrabble round office, eventually find .iso instead and mount it.

Wait ages. We are now over an hour into this install, and haven’t got past the preparation tool yet. Still useless progress bar stuck at 50%.

It’s done at last. Next, mount and run the SP1 iso:

http://www.microsoft.com/downloads/details.aspx?FamilyId=27673C47-B3B5-4C67-BD99-84E525B5CE61&displaylang=en

Wait again. This is when you need multiple computers in order to get on with your work.

Now Windows Update pops up to request a restart. I’m not sure if this is coincidence, or something triggered by the install. It doesn’t seem a good plan to restart when the SP1 installer is still chugging away, so I refuse.

Wait.

Done. Now the installer requests the inevitable Windows restart.

Still need to reinstall Silverlight beta 2:

http://www.microsoft.com/downloads/details.aspx?FamilyId=50A9EC01-267B-4521-B7D7-C0DBA8866434&displaylang=en

That one wasn’t too bad in comparison.

Overall: took longer than I’d like, but it worked.

A year or so a go I wrote a post called Adobe AIR: 10 reasons to love it, 10 reasons to hate it. Here’s the same kind of list for Microsoft’s Silverlight, based on the forthcoming Silverlight 2.0 rather than the current version. The items are not in any kind of order; they also reflect my interest in application development rather than design. It is not a definitive list, so there are many more points you could make – by all means comment – and it will be interesting to have another look a year from now when the real thing has been out for a while.

This Silverlight developer chart is available in full on Brad Abrams’ blog here, or in Joe Stegman’s Deep Zoom version here.

The pros…

1. The Silverlight plug-in means developers can target a single, consistent runtime for browser-based applications, rather than dealing with the complexity of multiple browsers in different versions. You also get video and multimedia effects that are hard or impossible with pure HTML and JavaScript; though Adobe’s Flash has the same advantages.

2. Execute .NET code without deploying the .NET runtime. Of course, the Silverlight plug-in does include a cut-down .NET runtime, but instead of dealing with a large download and the complexities of the Windows installer, the user has a small download of about 4MB, all handled within the browser. In my experience so far, installation is smooth and easy.

3. Performance is promising. Silverlight comes out well in this prime number calculator, thanks no doubt to JIT compilation to native code, though it may not compare so well for rendering graphics.

4. Support for Mono (Moonlight) means there will be an official open source implementation of Silverlight, mitigating the proprietary aspect.

5. Silverlight interprets XAML directly, whereas Adobe’s XML GUI language, MXML, gets converted to SWF at compile time. In fact, XAML pages are included as resources in the compiled .XAP binary used for deploying Silverlight applications. A .XAP file is just a ZIP with a different extension. This also means that search engines can potentially index text within a Silverlight application, just as they can with Flash.

6. Third-party component vendors are already well on with Silverlight add-ons. For example, Infragistics, ComponentOne and DevExpress.

7. Take your .NET code cross-platform. With Macs popping up everywhere, the ability to migrate VB or C# code to a cross-platform, browser-based Silverlight client will be increasingly useful. Clearly this only applies to existing .NET developers: I guess this is the main market for Silverlight, but it is a large one. The same applies to the next point:

8. Uses Visual Studio. Microsoft’s IDE is a mature and well-liked development environment; and since it is also the tool for ASP.NET, you can use it for server-side code as well as for the Silverlight client. For those who don’t get on with Visual Studio, the Silverlight SDK also supports command-line compilation.

9. Choose your language. Support for multiple languages has been part of .NET since its beginning, and having the .NET runtime in Silverlight 2.0 means you can code your client-side logic in C#, Visual Basic, or thanks to the DLR (Dynamic Language Runtime) Iron Ruby or Iron Python.

10. Isolated storage gives Silverlight applications local file access, but only in a protected location specific to the application, providing a relatively secure way to get this benefit.

The cons…

1. If Apple won’t even allow Flash on the iPhone, what chance is there for Silverlight?

2. Silverlight is late to the game. Flash is mature, well trusted and ubiquitous; Silverlight only comes out of beta in the Autumn (we hope) in the version we care about – the one that includes the .NET runtime - and will still lack support on mobile devices, even Windows Mobile, though this is promised at some unspecified later date.

3. The design tools are Expression Blend and Expression Design – but who uses them? The design world uses Adobe PhotoShop.

4. While having solution compatibility between Expression Blend and Visual Studio sounds good, it’s actually a hassle having to use two separate tools, especially when there are niggling incompatibilities, as in the current beta.

5. No support for the popular H.264 video codec. Instead hi-def video for Silverlight must be in VC-1, which is less common.

6. It’s another effort to promote proprietary technology rather than open standards.

7. Yes Linux will be supported via Moonlight, but when? It seems likely that the Linux implementation will always lag behind the Windows and Mac releases.

8. Silverlight supports SOAP web services, or REST provided you don’t use PUT or DELETE, but doesn’t have an optimized binary protocol like Adobe’s AMF (ActionScript Message Format), which likely means slower performance in some scenarios.

9. Silverlight is a browser-only solution, whereas Flash can be deployed for the desktop using AIR (Adobe Integrated Runtime). Having said that, yes I have seen this.

10. You have to develop on Windows. This is particularly a problem for the Expression design tools, since designers have a disproportionately high number of Macs.

Looks like I’ll be missing out on Silverlight’s big moment – the NBC Olympics site.

Annoyingly, it was happy to display the pre-roll ad.

I’ll be interested to know how Silverlight and the streaming servers for this event perform.