MSXML 5.0 with WinHTTP5

MSXML 5.0 installs and depends upon Microsoft® Windows® HTTP Services (WinHTTP) 5.0. WinHTTP 5.0 is a new server-side component that provides an updated Hypertext Transfer Protocol (HTTP) stack for developing server-based applications for the Web.

MSXML 5.0 uses WinHTTP 5.0 for the ServerXMLHTTP object, a server-side interface for handling HTTP requests. This object differs from the XMLHTTP object, which performs in a similar role as a client-side interface on most computers running Windows. The primary difference between these two interfaces is that XMLHTTP cannot be used in a server environment. This is because it depends upon the WinInet component, which was not designed to provide adequate performance in server-side use.

Because of the dependency between WinHTTP 5.0 and MSXML 5.0, you will probably need to deploy WinHTTP 5.0 with your applications if you are working with the following related technologies:

• Active Server Pages (ASP)
• Internet Server Application Programming Interface (ISAPI) extensions for Internet Information Services (IIS)

If you are developing server-side applications in these contexts with MSXML 5.0, be sure to distribute WinHTTP 5.0 or later with your application.

You should also be aware that if you are planning wide client deployment, you cannot use a component designed to use WinHTTP and MSXML for server-side applications in any client-side applications. This is because the WinHTTP component is not supported in Windows 9x/Me. Therefore, any code reference to the ServerXMLHTTP object will fail when executed on computers running these versions of Windows. For Windows 9x/Me, your application must use the older client-side XMLHTTP object.

Note   WinHTTP 5.1 will ship with the forthcoming release of Windows XP Server. This version will work side-by-side with WinHTTP 5.0. You will no longer have to monitor package and deployment issues for WinHTTP when you develop applications that use this platform.