You have already seen some use of the Sys namespace through examples in this chapter such as the previous Sys.Browser example. The Sys namespace is the root namespace within ASP.NET AJAX and a lot of classes and interfaces there are available for use within your JavaScript code.
Microsoft has extended upon the JavaScript library to provide you with the extra items that you are most likely going to want to work with when coding your ASP.NET AJAX pages. These extensions are similar to what you are used to in working with the .NET Framework.
The following table details the available objects found in the Sys namespace.
Object in Sys namespace
Description
Sys.Application
Manages client components that are registered with the application
Sys.ApplicationLoadEventArgs
Holds event arguments for the load event of the Application class
Sys.CancelEventArgs
Provides a means to cancel events
Sys.Component
Provides the base class for the Control and Behavior classes, and for any other object whose lifetime should be managed by Microsoft ASP.NET AJAX
Sys.CultureInfo
Like the CultureInfo object in the .NET Framework, this holds culture related settings
Sys.Debug
Provides tracing and debugging information
Sys.EventArgs
Allows for passing of event argument information
Sys.EventHandlerList
Provides a collection of client events for a component
Sys.IContainer
An interface that provides a common interface for all components that can contain other components
Sys.IDisposable
An interface that allows you to close, reset, or release resources
Sys.INotifyDisposing
An interface that provides notifications of disposing events
Sys.INotifyPropertyChange
An interface that provides notification of property changes
Sys.PropertyChangedEventArgs
Used by the propertyChanged event to signify which property changed
Sys.Res
Provides static, culture-neutral exception messages that are used by the Microsoft AJAX Library framework
Sys.StringBuilder
Provides the ability to perform string concatenation
Sys Exceptions
Raises an Error Object; these are exceptions raised by ASP.NET AJAX
Besides the root Sys namespace. You will also find Sys.Net, Sys.Serialization, Sys.Services, Sys.WebForms, and Sys.UI.
Sys.Net allows you to make Web service calls, work with the WebRequest object, work with Web service errors, and provides you with XMLHttp support.
Sys.Serialization helps you take care of the serialization and deserialization of JSON formatted data.
Sys.Services allows you to work with the ASP.NET services such as the ASP.NET membership and role management systems that were introduced with ASP.NET 2.0.
Sys.WebForms lets you deal with the loading and unloading of ASP.NET pages. Finally, Sys.UI allows you to deal with things occurring with the page's UI, such as where the mouse is located on the page, how to deal with keys being pressed, or dealing with the DOM.
