Key differences from the Apache HTTP Server

This section takes a high-level look at the main differences between IBM HTTP Server and the Apache HTTP Server.

IBM HTTP Server is based on the Apache HTTP Server (httpd.apache.org), developed by the Apache Software Foundation. IBM HTTP Server includes the following additional features not available in the Apache HTTP Server:

• Support for the WebSphere console.

• InstallShield for multiple platforms enables consistent installation of the IBM HTTP Server on different platforms.

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  Fast Response Cache Accelerator (FRCA) is available for AIX 5.x and certain Windows operating systems. It significantly improves HTTP Server performance when serving static content such as HTML files or image files.

• Dynamic content generation with FastCGI.

• Installation of IBM HTTP Server in multiple languages on all platforms.

Operational differences between Apache and IBM HTTP Server:

• The apachectl command is the only supported command to start IBM HTTP Server. We cannot directly invoke the httpd command because it will not find the required libraries. The apachectl command is the preferred command to start Apache V2.0 and higher, but the httpd command might work on the Apache server as expected, depending on the platform and how Apache was built. We can specify httpd options on the apachectl command line.

• IBM HTTP Server supports the suEXEC program, which provides for execution of CGI scripts under a particular user ID.

  • If we use the suEXEC program, we must install the IBM HTTP Server to the default installation directory only. The suEXEC program uses the security model which requires that all configuration paths are hard-coded in the executable file, and the paths chosen for IBM HTTP Server are those of the default installation directory.

  • When an Apache user chooses an installation location for Apache at compile time, the suEXEC program is pre-built with the chosen paths, so this issue is seen by the Apache users.

  • Customers need to use the suEXEC program with arbitrary configuration paths can build it with Apache on their platform and use the generated suEXEC binary with IBM HTTP Server. Customers must save and restore their custom suEXEC file when applying IBM HTTP Server maintenance.

• As a more flexible replacement for the suEXEC program (which is for other platforms), IBM HTTP Server supports SAFRunAs. The SAFRunAs directive provides for execution of CGI scripts and access to static files under a particular user ID. We can enable the SAFRunAs directive from the mod_auth_saf load module.