About UWM's Web Server

This document attempts to point out some of the differences you might notice in how the new Apache server works compared to our ancient NCSA server (retired 12/98). If you're just doing basic HTML, you can probably skip this altogether, as the new server is very similar to the old one in most respects. However, if you're using CGI programs, includes/SSI, .htaccess files, or log analyzers, please read on...

• Apache is pickier about some things that the old server let slide. For instance, the most common CGI problem is not printing the required HTTP headers first, and a cgi-bin program that the old server accepted may fail under Apache. Note that at a minimum, a cgi-bin program must supply at least this header:
  
  
  • Content-type: text/html
  
  followed by a blank line.
  
  
• If your .htaccess file is not world-readable, or if it contains errors, your entire directory and any subdirectories are no longer accessible from the web. The NCSA server simply ignored .htaccess files that were not world-readable. We looked through the Web directories and renamed the few inaccessible .htaccess files to .htaccess-NOT-USED to prevent some access problems, but if your .htaccess file causes errors you will have to remove/rename/fix it.

  If you are using a directive such as:
  
  

  • AddType   application/x-httpd-cgi   index.html
  
  You will need to change it to:
  
  
  • AddType   application/x-httpd-cgi   .html
  
  as Apache will only take a file extension, not a file name.
  
  
• UWM Redirects. Due to the many file system links added over the years to allow URLs to work with different cases (either "Dept" or "dept") or changed names, we've had the situation where a given page could have more than one URL (Dept/X, dept/x, Dept/x, dept/X). Unfortunately, these are usually interpreted as separate pages, making for confusing results with Search Engines, logging, etc. We have now added "redirects" in the server so that "duplicate" URLs are redirected to a single URL. Users will probably not notice this change. If you're using log analyzers, you may have to adjust the base URL you're looking for (which probably means you weren't counting all of the hits before).

  Note that this change does not affect personal pages.
  
  

• DNS lookups have been turned off in the server. As our server gets more and more busy, doing DNS host name lookups for each request is no longer desirable. This means that cgi-bin programs will only get the IP number of the request, and will need to lookup the host name themselves if needed. Also, .htaccess files should use IP numbers when possible, instead of host names. For example, the "only UWM" restriction ".uwm.edu" should be changed to "129.89." to avoid DNS lookups. Note that the server will do DNS lookups in cases where the host name is needed, but defaults to not doing it always.
  
  Note that this also means that the CGI environment variable REMOTE_HOST is usually not available.
  
  
• Logging Changes:
  
  
  • Apache now writes log files in the "combined" format, which includes "referer" and "agent" fields at the end of each log record. The old server used the "common" format which did not have these fields. Most modern log analyzers should handle both formats.
    
    
  • For efficiency, the actual raw log file written by the server is no longer publicly available. Instead, every 15 minutes, a separate process reads the raw log file, does DNS host name lookups (they were turned off in the server), and splits the entries off into dated public files. Each of these dated files will now contain ALL of the log records for that day, with NO log records for other days, and the old access_log names are now symbolic links to these files.
    
    
  • See the UWM Redirects section - Some log entries may be under different URLs than you were used to seeing in the old logs.
  
  
• If you're doing "complicated" things with cgi-bin or Server Side Includes, be sure to check the Apache Project's documentation:
  
  
  • Compatibility Notes with NCSA httpd. Most of these are server configuration issues, but there are some notes that pertain to .htaccess files.
    
    
  • Server Side Includes (mod_include), SSI, or now XSSI (eXtended Server Side Includes).
    
    
  • The NCSA Common Gateway Interface document is still a good reference for CGI programming.
    
    

We are currently running version 1.3.3 of the Apache web server software. For detailed information about our server, see the Apache User's Guide. Please report any problems to <www@uwm.edu>.

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Last update: July 27, 2000. --- URL: http://www.uwm.edu/apache/
Copyright 2000 by the University of Wisconsin-Milwaukee, all rights reserved.
If you have questions or comments about this page please send e-mail to: www@uwm.edu