Migrating a Web Server to IIS 5.0
Migrating a Web Server to IIS 5.0 |
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There are special considerations when you’re migrating Web applications from a UNIX environment. Not only do you need to be concerned with how the application functions on the Web server, but on the operating system as well. There are many differences between UNIX and Windows 2000 operating systems, and the degree to which your application is based on UNIX-specific technology affects how easy or difficult it will be to migrate.
The effort required to port a UNIX application to IIS 5.0 will be affected not only by the portability of the application, but also by the products and tools used to build it. This means that the database, round-robin DNS, developer tools, dynamic content pages, CGI applications, and any custom binaries or third party tools must work well with Windows 2000 Server.
The “ideal” UNIX-based application to port to IIS 5.0 would have the following characteristics:
This type of application would be a good candidate to migrate “by hand,” converting it to a CGI, ISAPI, or ASP-based application that can run natively on IIS 5.0.
Most applications won’t be so ideal. You might decide it isn’t cost-effective to migrate some or all of your CGI applications, for example, if they’re difficult to migrate, or if you have a large number of them. In this case, you might consider using a third-party tool such as PerlEX, a plug-in you can use with IIS 5.0 that dramatically improves the performance of Perl CGI applications. This way, you can run existing Perl CGI applications without creating a drain on IIS 5.0 resources. PerlEX also supports embedding Perl scripts within HTML. For more information, see http://www.activestate.com/plex/.
As an interim solution, you might also consider using a third-party tool that provides a UNIX-like environment for running applications on IIS 5.0. This way, you can gradually migrate applications to run natively on IIS 5.0, avoiding the need to rewrite a large amount of code in a short time frame. One such tool is Interix, by Softway Systems, Inc., which provides a Portable Operating System Interface (POSIX) environment. In addition, NutCracker, by DataFocus, has a run time that provides UNIX calls on Windows NT and Windows 2000. It uses the Win32 environment, which is more efficient than POSIX, and also provides access to COM.
For more information about available tools for migrating UNIX applications, see Additional Resources at the end of this section. In addition, see the following topics, Migrating a UNIX Perl Script and Converting UNIX Application Files.