This lesson will present you with a high-level overview of Microsoft Silverlight.
An Overview of Silverlight
Silverlight enables development of the next generation of Microsoft .NET-based media experiences and rich interactive applications (RIAs) for the Web. Silverlight is delivered as a cross-platform and cross-browser plug-in that exposes a programming framework and features that are a subset of the .NET Framework and Windows Presentation Foundation (WPF).
Support
The industry has been abuzz about Silverlight since the beginning of 2007 when Microsoft began demonstrating its power at developer conferences. In fact, no other development technology has been so highly anticipated since the arrival of the .NET Framework and Silverlight resources and examples abound on the Web. To spark developer interest in Silverlight, Microsoft launched several community Web sites dedicated to Silverlight development including the Silverlight home page (http://www.microsoft.com/silverlight) and the Silverlight.net community Web site (http://silverlight.net).
Early Adopters
In response to the overwhelming developer community anticipation for the arrival of Silverlight, many developers and companies have become early adopters of the technology.
Some example sites are listed below:
World Series of Poker
Discovery Channel
The Emmys
Home Shopping Network (HSN)
World Wrestling Entertainment (WWE)
Fox
XBOX 360
Netflix - uses Silverlight to allow subscribers to instantly watch movies on their PCs or Intel-based Macs.
Many of the published early adopter applications are featured in the Silverlight.net showcase.
The .NET Framework
Microsoft introduced the .NET Framework in 2000 as a new approach to software development. The .NET Framework borrowed ideas from the best practices in the software industry as well as brought new ideas to the table in an effort to meet developer needs and requests.
Virtually all programming languages manage data at some point. The primary reason that communication between applications created using C++, Visual Basic, Visual FoxPro, and other languages was difficult was because each language stored data being managed in a unique set of data types. For example, an integer in one language may not represent an integer in another language. Data needed to be converted to common data types to communicate between languages.
The .NET Framework introduced a common set of data types (the Common Type System) that is used by all .NET-compliant languages (C++, Visual Basic, C#, etc). Thus all languages can easily intercommunicate. Furthermore, all .NET-compliant languages render a common result when compiling code, Microsoft Intermediate Language (MSIL). (see footnote) MSIL can be deployed to any platform running the Common Language Runtime (CLR). Currently, the CLR is only available for Microsoft Windows although an open source version of the CLR was created for Linux (called the Mono Project). Code written by using the .NET Framework is compiled instead of interpreted resulting in much better performance than Java and competing technologies.
Microsoft took the Web development industry by storm with their .NET upgrade to ASP. ASP.NET put a new face on Web development through a compiled code architecture and improved state management and it provides access to the full functionality of the .NET Framework. ASP.NET is built around XML, supports the latest Web development standards, and allows for the creation of advanced Web Services.
The .NET Framework also provides improved data access and database integration through ADO.NET. For more information, see MSDN.
There are many more features and benefits of the .NET Framework than those mentioned here. The .NET Framework has become the leading software development environment available.
Introducing Silverlight What's New in the .NET Framework
As of the writing of this course, version 3.5 of the .NET Framework has been released. Version 3.5 includes features that encompass all facets of Windows, Web, and network development:
Includes just under 10,000 classes, methods, and properties.
Complies with the latest Web development standards.
Introduces revolutionary technologies used in Windows Vista development, rich media and user experiences, workflow management, security and authorization, and complete distributed communication protocols.
The .NET Framework can also be fully extended by developers to create custom classes and types. The functionality of the .NET Framework spans the server, the workstation, and the Web. The four primary additions to the .NET Framework as of version 3.0 are:
Windows Presentation Foundation (WPF)
Windows Communication Foundation (WCF)
Windows Workflow Foundation (WF)
CardSpace
Windows Presentation Foundation (WPF)
WPF is used to develop elaborate user interfaces like those that adorn Windows Vista and managed advanced media streaming and integration. WPF is the a complete revamp of Windows Forms so that user interface, graphic, and media development is now designed around the .NET Framework.
Windows Communication Foundation (WCF)
WCF encompasses the ASP.NET Web Services and .NET remoting functionality that was contained in the .NET Framework 2.0 as well as new communication technologies.
Windows Workflow Foundation (WF)
WF is used to model complex workflow processes.
CardSpace
CardSpace is the embodiment of new security and user authorization functionality.
ASP.NET AJAX
ASP.NET AJAX was developed to improve performance in the browser by making post backs and calls between the browser and server asynchronously. ASP.NET AJAX uses new built-in types and controls and JavaScript.
Both ASP.NET and ASP.NET AJAX are heavily dependent upon the ASP.NET page event life cycle, are tightly coupled to the server, and have a tough time competing with advanced, media-rich plug-in solutions such as Adobe Flash. Additionally, it is difficult to create Web applications that offer a consistent experience across all supported browsers and platforms by using ASP.NET and AJAX. In 2006, Microsoft began developing a solution to extend into the browser and offer media experiences more robust than competing plug-in solutions.
In 2007, Microsoft introduced Silverlight. (see footnote) Silverlight is a free plug-in that encompasses a subset of functionality from the .NET Framework and WPF. In a manner similar to the JVM (see footnote), Silverlight runs in the browser as a "sandbox" - a secure zone installed into the browser that accommodates Silverlight functionality while completely protecting the host platform from any possibly adverse actions performed by Silverlight.
Silverlight Architecture
Unlike ASP.NET, the bulk of Silverlight processing occurs on the client machine thus decreasing server resource utilization and improving the Web experience on the client. The figure below shows the difference between ASP.NET processing and Silverlight processing: 
When a client initially attempts to run a Silverlight application, if the Silverlight plug-in has not been installed on the client machine, it will be downloaded and installed. Upon subsequent requests to run the application, the application will instantiate on the client machine and make requests for resources from the server only when necessary. The Silverlight plug-in can be thought of as a scaled-down version of the full .NET Framework. It only contains those classes and functionality that are applicable to a Silverlight Web client and those were streamlined and optimized for use on the Web client machine.
Silverlight was designed using the same design paradigm as ASP.NET. Each page of a Silverlight application includes an associated code behind file that includes the code that handles events fired by the page. Silverlight resembles WPF in that it uses Extensible Application Markup Language (XAML) to construct the user interface (presentation layer). As Silverlight applications are composed of text-based files that include markup and code, they can be created using any text editor; however, more advanced tools and development environments such as Visual Studio or Expression Blend simplify the task significantly.
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