In order to write practical code, you need to know quite a bit about the classes you have to
work with. That means acquiring a thorough knowledge of the core class libraries that ship
Silverlight includes a subset of the classes from the full .NET Framework. Although it
would be impossible to cram the entire .NET Framework into Silverlight—after all, it’s a 4MB
download that needs to support a variety of browsers and operating systems—Silverlight
includes a remarkable amount of functionality.
The Silverlight version of the .NET Framework is simplified in two ways. First, it doesn’t
provide the sheer number of types you’ll find in the full .NET Framework. Second, the classes
that it does include often don’t provide the full complement of constructors, methods, properties,
and events. Instead, Silverlight keeps only the most practical members of the most
important classes, which leaves it with enough functionality to create surprisingly compelling
• mscorlib.dll. This assembly is the Silverlight equivalent of the mscorlib.dll assembly
that includes the most fundamental parts of the .NET Framework. The Silverlight version
includes core data types, exceptions, and interfaces in the System namespace;
ordinary and generic collections; file management classes; and support for globalization,
reflection, resources, debugging, and multithreading.
• System.dll. This assembly contains additional generic collections, classes for dealing
with URIs, and classes for dealing with regular expressions.
• System.Core.dll. This assembly contains support for LINQ. The name of the assembly
matches the full .NET Framework, which implements new .NET 3.5 features in an
assembly named System.Core.dll.
• System.Net.dll. This assembly contains classes that support networking, allowing you
to download web pages and create socket-based connections.
• System.Windows.dll. This assembly includes many of the classes for building Silverlight
user interfaces, including basic elements, shapes and brushes, classes that
support animation and data binding, and a version of the OpenFileDialog that works
with isolated storage.
• System.Windows.Browser.dll. This assembly contains classes for interacting with
• System.Xml.dll. This assembly includes the bare minimum classes you need for XML
processing: XmlReader and XmlWriter.
Thats all you need to know to write a Silver Light apps.