Programming Microsoft Outlook and Microsoft Exchange, Second Edition (DV-MPS Programming)

Whereas IIS 4.0 and Windows NT 4.0 provided an excellent platform for building Web applications such as OWA, Windows 2000 and IIS 5.0 provide an even better one. For this reason, Microsoft supports running OWA on IIS 5.0 and Windows 2000. To run OWA on IIS 5.0 and Windows 2000, you must upgrade your OWA server to at least Exchange 5.5 Service Pack 3. Using Windows 2000 and IIS 5.0 offers a number of benefits, especially for ASP developers, and I'll discuss them in the next few sections.

Improved ASP Support

In versions of IIS prior to 5.0, the scope of a Web application was a virtual directory. So if you accessed an application in the virtual directory sales, and then you transferred the user to the virtual directory contacts, you lost all the application information from the sales application. Why? IIS considered these two Web applications to be separate because they resided in distinct virtual directories. However, with IIS 5.0, which uses the Server.Transfer method, this directory limitation is removed. With the Server.Transfer method, you can specify another ASP file to execute in a different ASP application without losing all your existing variables in the calling ASP application.

IIS 5.0 also supports much better error-handling than previous versions. When IIS detects an error in your application, it passes you an ASPError object. Using this object, you can determine the error number and the line of the source code as well as the number of the code line that caused the error. From this information, you can display custom error information to your users.

Improved Scripting Support

IIS 5.0 includes new versions of both VBScript and Jscript. While I can't cover all the new features of both languages, I do want to make you aware of two key enhancements in VBScript. The first one is support for the With statement. This support makes it easier for you to instantiate an object and then call methods and set properties on the object without rewriting a bunch of code. The second enhancement is support for regular expressions, which allows you to perform complex evaluation and manipulation of string variables.

Improved Security Features

IIS 5.0 supports the standard Digest authentication. Digest authentication is similar to Basic authentication, but Digest authentication does not send the user's password over the wire. Instead, Digest authentication uses a hashing algorithm to form a hexadecimal representation of a combination of user name, password, the requested resource, and the HTTP method.

WebDAV Support

IIS 5.0 supports WebDAV. WebDAV is a set of extensions to HTTP that allows you to send to your Web server commands that will open, edit, move, search, or delete files. Exchange 2000 supports WebDAV, so you'll learn more about it when I discuss Exchange 2000.