Migrating a Web Server to IIS 5.0

Migrating Web Applications

An important decision to make when migrating to IIS 5.0 is how to handle existing Web applications. IIS 5.0 supports applications based on CGI, ISAPI, and ASP. In some cases, it is best to simply port an application to IIS 5.0, making only a few necessary changes. This is usually true for existing ISAPI extensions and ASP applications, which make efficient use of server resources, and for CGI applications that are not heavily used. However, you might decide to rewrite CGI applications as either ISAPI extensions or as ASP applications in order to improve their scalability and performance as well as to simplify the development process. This will save both time and money.

This section discusses the following:

• Issues to consider when deciding whether to port a CGI application directly to IIS 5.0 or to rewrite it as an ASP application or ISAPI extension.
• The basic work involved in each approach to migration and references to more in-depth information.
• Changes that must be made to UNIX-based applications before they will run on IIS 5.0.

This material assumes you’re familiar with Web-based applications and CGI. You can find additional references on migrating and porting applications in Additional Resources at the end of this section, and more information about developing with ASP in Developing Web Applications in this book. For information about installing and configuring applications, see the “Configuring Applications” topic of the IIS 5.0 online product documentation.

See the following:

• IIS 5.0 Application Technologies
• Deciding to Port or Rewrite CGI Applications
• Porting CGI Applications
• Special Considerations for UNIX Applications
• Converting CGI to ISAPI
• Migrating from CGI to ASP
• Reproducing Common CGI Services

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