Jason Zander's WebLog : Video

Lang.NET Videos Back Online

Jasonz — Fri, 14 Mar 2008 06:44:00 GMT

I had posted a pointer to our Lang.NET videos here, but unfortunately the site they were hosted on was overwhelmed by the interest. The videos have been re-posted to a more robust network and are ready for viewing again. Please accept our apologies for the time delay and initial failure. I hope you will enjoy the content...

Side by Side In Process CLRs Start with Silverlight

Anonymous — Thu, 10 May 2007 22:31:00 GMT

When we started working on managed code for Silverlight one scenario I wanted to see working was the ability to create a new browser or shell in managed code that could still browse to and execute rich web content. We spent (endless) time debating if this scenario should simply target the desktop CLR if it were installed and just use one CLR. In the end my main concern about that solution was ensuring 100% behavior compatibility. We strive really hard to reach this on the desktop already, and at some point just being able to execute what you wrote against is the best solution. So instead we went down the road of creating a separately factored CLR which could run side by side in the same process. To test this, I wrote a small managed application which hosted shdocvw.dll (IE’s core browser engine) and browsed to a Silverlight enabled web site. The first few times this was not a pretty experience <g>, but that was quickly fixed.

Enabling side by side CLRs in the same process not only enables this scenario, but it removes a long standing complaint from developers trying to write applications that implement add-in models for extensibility. In these cases, you often want to load and bind to the version of the CLR your add-in was built for. Previously one had to roll forward to the latest and greatest version to pull this off. It does work, but can be a little painful.

This video gives a demonstration of running two CLRs in the same process using a WPF demo I blogged about here:

There are a few things to notice in this diagram:

· There is no retroactive change to Versions 1.0, 1.1, or 2.0 of the CLR. Only one of these may be in the process at the same time. The diagram shows V2.0 (3.0 and “3.5” are built on top if used).

· Silverlight can run side by side with any one of the V1.0, V1.1, or V2.0 CLRs.

· Future versions of the CLR (which are under development already) will run side by side with the original desktop CLR instances and Silverlight.

Now that we have this feature, you may ask why it wasn’t there from the beginning. There were always two main considerations we had historically for not going down this road. The first is thread suspension. You need to ensure that if two CLRs are suspending threads to do a GC they don’t suspend each other in the process (there are some XML dlls out there today which do a poor job of this). The second consideration is the performance of the resulting process. Each CLR has its own GC heap and loaded code; they do not share data with each other (any interop between them must be done through unmanaged code / COM).

Given all of this, it is still our recommendation that if you are designing a new extensibility API for your application, try to make it work well with the add-in running out-of-process. This really does provide the cleanest way to isolate 3^rd party code and keep the best possible compatibility. However if you are using an existing API extensibility model (sidebar, browser, etc) that was not designed for this, this new feature does simplify your life a lot.

Tip/Trick: Embedding ActiveX in WPF with WindowsFormsHost (Video Demo)

Anonymous — Mon, 07 May 2007 23:03:00 GMT

I was looking for instructions on how to embed ActiveX in a WPF application and didn’t find a ton of stuff out there. After getting my demo working, I decided to record it and post it here for anyone else trying to make this work. In my example, I created a WPF “Browser” that embeds the IE control (shdocvw.dll) and uses WPF for the outer control. I will be using this sample application in my next video.

The basic instructions for getting this working are as follows:

1. Create a WPF application shell (I used Visual Studio “Orcas” Beta 1)

2. Create a Windows Forms Control assembly with the ActiveX content

3. Use the WindowsFormsHost class to embed the Windows Forms Control into the WPF application

The code is pretty straightforward for this. The following is the XAML for the application:

<Window x:Class="WPFApplication5.Window1"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Title="Window1" Height="300" Width="800">

</Button>

</Canvas>

</Grid>

</Window>

This markup creates a Canvas for the URL text box and Go button at the top of the application. It leaves room for the browser portion to be added later. The next step is to create the Windows Forms Control. This control is super easy to create, just drag a WebBrowser control wrapper onto the form itself. In my sample I’ve added one new public method to allow the URL to be set. The entire code for the control then winds up as follows:

namespace BrowserControl

{

public partial class UserControl1 : UserControl

{

public UserControl1()

{

InitializeComponent();

}

public void SetUrl(string url)

{

this.webBrowser1.Url = new Uri(url);

}

The final step is to create add the WindowsFormsHost control into the WPF element tree. The code then adds a Click handler for the “Go!” button so that we can set the URL of the browser control to the text value the user has typed into the address text box. The entire code for the WPF application then winds up as follows:

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Shapes;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Forms.Integration;

namespace WPFApplication5

{

public partial class Window1 : Window

{

BrowserControl.UserControl1 _Browser;

public Window1()

{

InitializeComponent();

WindowsFormsHost host = new WindowsFormsHost();

_Browser = new BrowserControl.UserControl1();

host.Child = _Browser;

host.Margin = new Thickness(0, 35, 0, 0);

this._Grid.Children.Add(host);

this._GoButton.Click += new RoutedEventHandler(_GoButton_Click);

}

void _GoButton_Click(object sender, RoutedEventArgs e)

{

_Browser.SetUrl(this._UrlTextBox.Text);

}

Now when you run the application, you get the following:

That’s all there is to it! I hope you find this sample useful. Next up I'm going to use the sample to talk about CLR versions now that we have Silverlight available.