Silverlight HVP Design, Refinements

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Design Update 

This was posted on Dec. 29 and updated on Dec. 30. The significant changes are to the Configuration and Marker Events sections

This blog post extends the  previous post in which I discussed the IMarkerEventHandler interface and how it might be implemented.

Readers and Frames

The design calls for one or more Pages each of which may have any number of UI modules. The default case is to have a TableOfContents module, a LinksDisplay module and a Reader module.

A Reader houses Frames where a Frame is a set of controls.  The Reader knows which frame to create and manages the lifetime of Frames.

A given frame has a known set of controls. For example, Frame-Type-1 might house the  HVP-extended version of the Silverlight Media Framework player (as described in this blog post) and Frame-Type-2 might display an html page and have a set of navigation controls.   (More on readers and Frames early in January)

Configuration

We anticipate using XML configuration files (delivered via WCF RIA Services and instantiated by MEF into a collection of business objects that for now I’ll call  HVPLayout. 

Marker Events

The meaning and actions to be taken by a Frame in response to hitting a marker in the video will be managed by the IMarkerEventHandler (MEH) implementing class. as described in the previous post mentioned earlier. 

One approach is to have the Marker Event Handler class  own a collection of HVPMarkerEvent business objects, each representing one association between a marker, its time, its type (link, etc.) and whatever other information the MEH class will need to raise the appropriate event.  A second approach, and one that is gaining a lot of traction, is to bring in the EventAggregator from Prism.

Supporting Legacy Videos

The Silverlight HyperVideo Player will continue to support existing videos that do not have markers nor our config files by having a default layout in which there is a reader that takes up the entire page, and that reader contains a Frame that itself contains nothing but our extension to the SMF player.

Other Technologies

We are actively looking at when using an IoC (Inversion of Control) container such as Ninject would provide services that are not otherwise available. For now, we believe MEF will provide the Container services, configuration and interaction with Unit Test that we need.

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About Jesse Liberty

Jesse Liberty is an independent consultant and programmer with three decades of experience writing and delivering software projects. He is the author of 2 dozen books and multiple Pluralsight courses, and has been a Senior Technical Evangelist for Microsoft, a Distinguished Software Engineer for AT&T, a VP for Information Services for Citibank and a Software Architect for PBS. He is a Xamarin Certified Mobile Developer and a Xamarin MVP, Microsoft MVP and Telerik MVP.
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