Description:

mod_ext_filter presents a simple and familiar programming model for
filters. With this module, a program which reads from stdin and writes
to stdout (i.e., a Unix-style filter command) can be a filter for
Apache.

This filtering mechanism is much slower than using a filter which is
specially written for the Apache API and runs inside of the Apache
server process, but it does have the following benefits:
- the programming model is much simpler
- any programming/scripting language can be used, provided that it
allows the program to read from standard input and write to standard
output
- existing programs can be used unmodified as Apache filters

Even when the performance characteristics are not suitable for
production use, mod_ext_filter can be used as a prototype environment
for filters.