The Microsoft web-to-host model uses SNA Server to provide web-to-host connectivity between the host system and a web server, such as the Microsoft Internet Information Server (IIS). In this model, web browsers and servers communicate using the HTTP and TCP/IP protocols over the network. The web server, in turn, communicates with SNA Server using a defined server interface, such as ISAPI. The SNA Server computer then communicates with the host system using the SNA protocol over a defined connection.
Figure 12.1 Microsoft web-to-host architecture.
Where you deploy each component of your network is a matter of choice. Smaller enterprises may be able to deploy a web server and SNA Server on the same Windows NT Server computer. To handle a greater number of server and connection requests, it is recommended that you install the web server and SNA Server on separate Windows NT Server computers.
The Internet Information Server (IIS) is the recommended web server for Windows NT Server systems because of its tight integration with the management and administrative features of the operating system. Integration with Windows NT Server also lets you easily couple IIS with other BackOffice applications, such as Microsoft SQL Server or Microsoft Exchange Server, to web-enable enterprise applications such as e-mail and database access.