C# in a Nutshell, Second Edition

Name

FileWebRequest

Synopsis

This subclass of WebRequest provides access to resources that use the file URL scheme (such as a file on your local filesystem). Use WebRequest.Create( ) with a file:// URL to create an instance of this class. The WebRequest.Create( ) method returns an instance of this class as a reference of type WebRequest.

You may feel a small sense of confusion regarding this type and the “file:” protocol scheme; if a program needs access to a file on the filesystem, why not simply open a System.IO.FileStream instead of using WebRequest.Create("file:/...")? In terms of straight functionality, the System.IO.FileStream call more closely represents the fact that this resource is coming from disk; however, due to the ubiquity of HTTP servers growing within the enterprise, there are often times when a system wishes to equally represent HTTP URLs and filesystem paths within an arbitrary context. For example, a configuration file might be used to indicate where to retrieve user preferences; by specifying the location as a URL rather than an absolute file location, storage of user preferences is permitted on a centralized server without any additional code. (This allows a kind of “roaming preferences” capability within the system.) Many of the .NET tools also use this approach to identify “files” to act upon via command-line parameters.

public class FileWebRequest : WebRequest {
// Protected Constructors
   protected FileWebRequest(System.Runtime.Serialization.SerializationInfo ...