Mike

Thanks for the comments. It wan't my intent to say whether or not using these features is a good idea or a bad idea. It is an interesting question though. Programming tools often get used in unexpected ways. If you offer the capability to do something, chances are that some will take advantage of it, bad idea or not. And applications evolve - say you've done a Silverlight app, and then find that some feature request can be easily fulfilled with a dash of COM interop? Would you rewrite in WPF, just because that would be a "bad idea"?

I think the addition of COM to Silverlight 4 is a huge change to the platform, for better or worse. And I think Microsoft should keep parity with the Mac version; it was meant to be WPF *everywhere*. Perhaps few will use it though; we'll see.

Tim

Hola vengo con los enlaces interesantes de hoy pero quisiera resaltar uno y establecer un pequeño

One thing I did not see was that it looks like .Net 4 client profile install is going to be about 40 megs!

thats way smaller than a 3.5 Sp1 install at over 150 megs!

so .Net 4 client is going to be much less hassle to get on customers boxes when it hits RTM / TRW in about 2 months.

I think the difficultly of getting a .NET version > 2.0 deployed cannot be over stated.  Silverlight is a much better soln and has less deployment friction.  There are some serious deployment issues with Silverlight however.  For an enterprise rollout on shared workstations (more than one user uses the same computer), having them accept the trust elevation and accept to have it run on the desktop doesn't work.  There needs to be a group policy way to override these UI elements.  How do I deploy to 3000 workstations in a 1 month rollout and have the user just run the Silverlight app?  Local storage can't go to the "all users"/public documents folder.  Why NOT?   Add more flexibility to the Silverlight sandbox via group policy.  Allow me indicate what directories on the machine Silverlight can have full control over.  Also, please if I can get the web cam, why on earth can't I get to ANY serial or USB port that I need to from Silverlight?  Let me open up any tcp/ip port (socket) I want to by policy as well.  How about including a basic ADO .net stack, serial/usb port access, and more file i/o ALL controlled of course by policy (in this case Group Policy), that would avoid much of the need and security risks of COM interop.

Just expand these settings:

www.microsoft.com/.../grouppolicysettings.aspx

Then we would really be able to build the easy to deploy hybrid (client/webservice) enterprise applications.

Hi Mike,

Rationally I agree with you. As wierd as I felt seeing ASP.NET desktop applications (you, corporate intranets), that was at least justifyable because skills of writing ASP and WinForms are essentially different. So, if you have ASP developers only - why not.

But Silverlight instead of WPF for Windows desktop app (especially Win7 desktop app)  - what is really the point?

But I still see that this going to be favorable trend in coming years. And I cannot quite understand why.

May be it's just because developing in SL gives you hope you can easily adjust your SL Win app to web, or Mac? This never going to happen if you have bunch of refs to COM, but still it's a warm feeling.

COM Interop in Silverlight 4 should be used very sparingly and only if there is no other user-effective way of achieving the same outcome.  For example, we were forced into using COM interop to add screen-capture capabilites to our application.

The main reason to not use it is because it destroys the cross-platform run-anywhere nature of Silverlight.  Being able to provide 1-click trialing of your software to potential visitors on your website (using Silverlight) is such a huge benefit for software developers that it amounts to a significantly higher number of sales (compared to download-and-install-trialware).  From a startup's perspective this is a huge plus with Silverlight and AIR.

Luckily with Silverlight we can partition the areas off that need to use COM and inform the user of this as they need these capabilities, allowing for gradual enhancement whilst still providing the browser-based (even though it will be running as out-of-browser) software experience to users.

It's going to be very interesting to see what sort of native capabilities Silverlight provides on the Mac and Linux.

Great conversation piece Mike and it's just another great feature in our Silverlight bag of tricks.

Mike

I don't get it.  With SL4, you can have a button that takes you to OOB for EXTRA features, otherwise, you stay in Browser... OR,

You go OOB, and have advanced functionality loaded via Prism or MEF.

Why is is one or the other, with SL4, you can have both!

BTW, if you're worried about COM interop and having the full .Net framework, just develop in C++ for your COM object, and you're guaranteed to run.

So it looks like the Silverlight, will become another windows only technology.

Choose a tool based on your target platform. Creating Windows desktop app using ASP or Silverlight is similar as designing PC with 64K memory and assuming it will never be a time that people will need more than 64K (remember that time?). Using ASP just because there is no one in the office has knowledge to write Win App is just too funny.

Mike there are a couple of articles on building a COM object, downloading it from a website, and registering it, ALL in a SL4 OOB app, it's not that hard.

The problem they encounter is that they develop the COM object with C#, and therefore have to worry if the full framework is there, and that it's the proper version.

That's why I said to write the COM object in C++, and it's GUARANTEED to run on any windows platform, no dependencies to worry about.

You blew past my comment that you don't have to choose, you can have both cross platform capability AND Windows only capability, and use the ones that are appropriate.

The point is that I don't need to limit myself to WPF, with SL4, I can do it all, and deliver it all over the web through the browser.

There are places for WPF, I just don't see any reason for me to even consider WPF for 99.999% of what most customers want or need, and WPF is nowhere as flexible as SL4... period.

Great Mike, and I totally agree with your last sentence.

The fact is that SL4 provides so much flexibility to solve these problems that WPF becomes a specialized solution, here's my thinking.

Since SL4 can be the ultimate delivery product, if you need WPF functionality, THEN download the WPF app from the OOB experience!

I love SL4 because I have the option to stay in the browser, go to OOB, all the while maintaining 100% cross platform, and then you have the "Nuclear Option" of going Windows only, ALL in one app.

SL4 doesn't eliminate the need for WPF, it just places WPF in a smaller niche.

One of the things which has been noticeable by its absence is any form of blogging by the people who are developing Silverlight for OSX; who are the people involved?  Presumably there's a big team of developers, but do we know who they are?  Nope.  Let's see/hear who they are :-)

great topic!

Silverlight 4 – Writing a Windows-Only Application via COM Interop? - Mike Taulty's Blog - Mike Taulty's

I agree that it's definitely to be used sparingly, but it's better to have the feature and the option to use it than not. It can be frustrating as a developer to always have to program for the lowest common denominator, and COM interop at least gives some option for those of us who want to provide some accelerated functionality beyond what Silverlight alone can offer.

As an example ( apologies for the shameless plug ), see my post on using CUDA with Silverlight via COM.

www.planetmarshall.co.uk/.../silverlight-and-cuda-interop

Silverlight 4에서 COM 지원하는 것과 관련한 많은 이야기들 중에 하나 윈도우에서만 돌아가는 Silverlight 애플리케이션을 만들것인지?

I recently came across your blog and have been reading along. I thought I would leave my first comment. I don't know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.

Lucy

http://dataentryjob-s.com

With file system access and now COM Interop, Silverlight 4 is sounding more like ActiveX. I think it is a terrible idea to put WIndows only features in a runtime that is supposed to be cross-platform. Sorry MS, you are really losing me here.