Chapter 7. Filters

Filters are a mechanism introduced in Apache 2.0 to preprocess client POST data before it is seen by the content handler, and to postprocess the output from the handler before it is sent back to the client. Filters can be chained and can modify the metainformation as well as the data itself. They can be used explicitly and are also used internally by Apache, for example, for implementing SSL encryption. Table 7-1 lists the filters provided by standard Apache modules.

Table 7-1. Standard built-in filters

Filter name	Module	Description
DEFLATE	mod_deflate	Output compression
INFLATE	mod_deflate	Input uncompression
INCLUDES	mod_include	SSI processing
SUBSTITUTE	mod_substitute	Response body substitutions