Communicating between two Silverlight objects on a single page

Not sure where I stumbled on it, but recently I watched video online where as the video was playing, a banner ad on the same page changed as the context of the video changed.  I was intrigued by the potential this technique had in interactive marketing.  As I was watching the video I was envisioning a character picking up a can of Pepsi and at that moment a corresponding banner ad somewhere else on the page switching to an ad for Pepsi.  This could be a very powerful way to create interactive calls to action.

This got me thinking about how I might duplicate that technique in Silverlight 2. I figured that the first step was to figure out a simple way communicate between two distinct Silverlight object which exists on the same page.  For this example I am going to have one SL object contain a series of Buttons, while the other SL object contains a single TextBlock.

In the image above the red box I refer to as slObject1, where the blue box I refer to as slObject2.  Both of these <objects> have unique id’s and point to their own respective Silverlight Project and both have been placed in a single html file. 

In this example my slObject1 will be executing a Javascript function, which in turn will be calling an internal function inside of slObject2.  To do this I simply add a reference to the “System.Windows.Browser” namespace and call the Invoke method of the Window object.  here is what my button click handler looks like. 

Once I have this defined I can now go back into my default.html file and define this Javascript function.  The function finds the appropriate html object and calls the internal function in slObject2. 

To create my “UpdateTextBlock function I need to add a few things to the slObject2 project.  First I have to go into my App.xaml.cs file and enter the following in my Application_Startup handler.  “HtmlPage.RegisterScriptableObject("Page", page);”  This registers a managed object for scriptable access by JavaScript code.  Once registered I can create my methods as follows.

That is all there is to it.  Now that I have the ability to communicate between the two SL object I can go after a more complicated implementation.

Code: SLObjects.zip