Server-side imagemaps are a built-in function of the Apache Web server used
at cscweb.net. Because Apache is a descendant of the NCSA
httpd package, imagemap control files are in "NCSA Format"
(programs such as Adobe PageMill will ask you this; the other common choice
is "CERN Format").
For a walk-through, we recommend the
tutorial from NCSA httpd, and the
Apache documentation for
the imagemap module. The Apache information is more up-to-date, but
the NCSA tutorial may be easier to read.
Once you have a .map file and an image you wish to use as an
imagemap, use the following HTML to implement your imagemap:
...where mapfile.map and image.gif are your
imagemap control file and image file, respectively. You are not required
to use a GIF file, of course; other image formats are also acceptable.
<A HREF="mapfile.map"><IMG SRC="image.gif" ISMAP></A>
If there is any problem with your imagemap, the server will usually return
a very generic error message. The most common problems causing this are:
Unfortunately, there is very little in the way of diagnostics available
from the server. Nothing is generated in the error logs.
- The mapfile isn't a proper text file. This often happens if you
transfer the file via FTP from a Macintosh or PC, without specifically
setting the "Text" or "ASCII" option. You shouldn't
rely on your FTP client to automatically recognize text files and transfer
them in the appropriate mode.
- The URLs in the mapfile are relative instead of absolute. An absolute
URL always begins with http://. Absolute URLs are recommended.
- The mapfile is in CERN format rather than NCSA, or has some other