Miguel de Icaza 细说 Mix 07大会上的Silverlight和DLR

Mono之父Miguel de Icaza 详细报道微软Mix 07大会上的Silverlight和DLR ,上面还谈到了Mono and Silverlight, 实现WPF目前不在Mono团队的近期计划之内,不过Silverlight for linux是不远的将来.就可以用.索性将他转载过来,内容如下:

Mix 07, Silverlight, Dynamic Languages Runtime and OpenSource
A very impressive set of demos at Mix 07, the 72 hour conversation that Microsoft is having in las Vegas. The focus was mostly around Silverlight, Microsoft's new web pluging to author rich application and tools used to design this content. The whole Expression suite was adorable, and Blend is fantastic. The demos were pretty amazing, Scott built a nice animation for an airline reservation system on stage:

Silverlight and WPF

Today Microsoft announced two Silverlight editions: one that went into beta (Silverlight 1.0) and is a relatively simple technology. Silverlight 1.0 uses a retained graphics system (a canvas) that exposes the internal structure to the browser DOM. It has no scripting capabilities built into it, all the scripting support is actually done by the Javascript interpreter in the browser and all changes are done by talking to a Javascript object exposed by the hosted Silverlight surface. The scene definition is done using the XAML markup using a subset of the WPF primitives available in the full-blown WPF. Then the big announcement came: The second edition was Silverlight 1.1, and this one is a different beast altogether. 1.1 extends the model by embedding a complete Common Language Runtime. Here is the slide that Scott used for this part of the presentation:Scott did a demo of a chess program that had logic built with JavaScript and C#, notice the nodes per second computation:The outcome of the famous battle between dog vs vampire:There are a handful of changes to the runtime. Here are some notes on what I found out about it today. It might not be complete nor accurate:

• A new security system: Unlike the CAS there is no stalk walking but instead there are trusted and untrusted assemblies. This is part of a new sandboxing model.
• Trusted assemblies have a way of flagging entry points as being untrusted. which requires that the caller be a trusted assembly. This means that calling things like FileStream File.Open (string filename) from an untrusted assembly is not permitted. Instead developers would call something like FileStream File.OpenDialog(...) (which is hosted in a trusted assembly) and this would in turn call File.Open(string) and this would return a FileStream that the user selected with a dialog box.
• The API has been trimmed down: some classes were removed that did not make much sense for the core.
• A Minimalist WPF implementation: this is now available as a new assembly. This implementation at this point does not seem to have support for high-level controls like Buttons or Sliders, those have to be authored in a per-application basis. There is talk about which pieces belong in the minimal WPF and which pieces do not. In my opinion, keeping the controls out was a good idea as the controls in the real WPF are a bit too big.
• Dynamic Language Runtime: the dynamic language runtime is an integral part of the Silverlight distribution.

Dynamic Language Runtime

The Dynamic Language Runtime was announced today. Jim Hugunin's blog has the details and rumor is that in the next couple of days/weeks he will be posting on his blogs the technical details behind the design of the DLR.Binaries of the DLR were released today as part of Silverlight 1.1, and the source code was included with IronPython 2.0 (also released today). The release for the DLR is done under the terms of the Microsoft Permissive License (MsPL) which is by all means an open source license. This means that we can use and distribute the DLR as part of Mono without having to build it from scratch. A brilliant move by Microsoft. During the keynote they announced support for four dynamic languages built on top of the DLR: Python, JavaScript (ECMAScript 3.0), Visual Basic and Ruby. The rumor on the halls is that IronPython and Ruby will be released under the MsPL license, while ECMAscript and Visual Basic will continue to be proprietary. From Jim's announcement:

For the short term, our focus is on using a small number of languages to drive the first wave of DLR development where we can work closely and face-to-face with the developers in order to iron out the worst kinks in the DLR design. After this initial phase, we want to reach out to the broader language community. If you're building a language on top of .NET and are interested in supporting dynamic language features then we want your feedback on the DLR. However, I'd discourage you from trying to implement on top of the DLR today. I don't want you to get frustrated trying to work with these really early bits and then not be interested in working with us when we're better prepared to engage with the language community. We plan to kick off a broader engagement with language implementers at the upcoming lang.net conference in three months - at the end of July. This will be the best place to really engage with the DLR and let us know what we got wrong.

Mono and Silverlight

For a long time a common question that the Mono team was when we were planning on implementing WPF. Most people want to hear a date like "tomorrow", "next month", "in a year". But the answer is more complex than just thinking "we can do this in N months". We as a team have to evaluate the cost of implementing a technology and contrast it with the impact that such technology would have. With our finite development resources (in the Mono community and the companies contributing to it) we have to pick our battles. And implementing WPF was never really high up on the priority list for a couple of reasons:

• WPF requires a very big investment before things will start working.
• Users of WPF is limited to those starting new applications and are willing to start those applications using WPF.
• Only a minority of existing users (Windows.Forms) were willing to rewrite their software to move it to WPF. The rest basically will continue developing Windows.Forms and using the technologies they have been using for the time being.

So it is fair to say that we currently do not have plans to look at WPF. But a Mono-based Silverlight is an entirely different story. Unlike WPF that requires people to rewrite their software to take advantage of it, Silverlight is aimed at the Web and it will become a nice complement, a way of spicing up existing web applications without rewriting what already works. It makes tons of sense for us to start looking at an implementation of Silverlight on Linux with Mono. There is already a XAML loader, it is the perfect excuse to use Antigrain for high-speed graphics and that only leaves the pesky media issue to be solved. In fact, am kind of happy that Microsoft did not do the port themselves as implementing this sounds incredibly fun and interesting.

Upsides

The major upside of this show has been how open the Microsoft folks have been open to discuss technicalities of any sorts. I had the chance of participating on an open source panel at the conference and PHP, Mozilla, SubSonic.NET and Mono were well represented and I did not fell any angry mood from anyone. There is also a surprising amount of talk about using the MsPL license, again, all good news. Finally, I also made tons of new friends, have had a great time with everyone I have met here. I also noticed that both Jon Udell and Dave Winer both look happier, they were always smiling,

IE 8?

Someone mentioned (and I forget whom it was) that talk about IE8 was strangely missing from the whole conversation. There were no announcements about new upcoming features in IE, no mention of whether IE8 will support what-wg nor any future plans.

Predictions

So how did my predictions score?

• "They will spend most of the time showing the new features in the recently released Orcas and probably the Silverlight media encoder." At least on the keynote there were little demos of Orcas, most of the demos were demos about Expression, but they did show the Silverlight media encoder. Am going to give myself half a point.
• "There will be a fresh Silverlight update." score 1.
• "Blend and Expression Design will probably ship as a final product, or a new beta will be released." They did. score 1.
• "Dynamic Language Runtime: a set of class libraries with some sort of supporting infrastructure in the CLR to help dynamic language authors speed up their code.". score 1.
• "_Javascript: probably Microsoft will announce that they are upgrading the JScript compiler in .NET." Although they did announce that it would be writing a new JavaScript compiler, it is not clear if its a research prototype to test the DLR or the real thing, so am going to go with half a point.
• "Silverlight will bundle a micro-clr." Silverlight bundled a full CLR. So zero points, although I was close.
• "Silverlight for Linux. And if there is no announcement, we should try to get someone drunk enough to get them to do it." There was no announcement of Silverlight for Linux, but I was still kind of joking. But I did get drunk with senior Microsoft employees. One point.

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