NAME

Servlet::Filter - filter interface

SYNOPSIS

  $filter->setFilterConfig($fconfig);

  # later

  $filter->doFilter($request, $response, $chain);

  my $config = $filter->getConfig();

DESCRIPTION

This is the interface for an object that performs filtering tasks on the request for a resource, the response, or both.

Filters perform filtering in the "doFilter()" method. Every filter has access to a Servlet::FilterConfig object from which it can obtain its initialization parameters and a reference to the Servlet::ServletContext which it can use, for example, to load resources needed for filtering tasks.

Filters are configured in the deployment descriptor of a web application.

Examples that have been identified for this design are:

Authentication Filters
Logging and Auditing Filters
Image conversion Filters
Data compression Filters
Encryption Filters
Tokenizing Filters
Filters that trigger resource access events
XSL/T Filters
MIME-type chain Filters

METHODS

doFilter($request, $response, $chain): This method is called by the container each time a request/response pair is passed through the filter chain due to a client request for a resource at the end of the chain. The filter chain passed into this method allows the filter to passon the request and response to the next entity in the chain.
A typical implementation of this method would follow such a pattern:

1.: Examine the request
2.: Optionally wrap the request object with a custom implementation to filter content or headers for input filtering
3.: Optionally wrap the response object with a custom implementation to filter content or headers for output filtering
4.: 4 a)
Either invoke the next entity in the chain by calling "doFilter()" on $chain,
5.: 4 b)
or block further filter processing by not passing the request/response pair down the chain
6.: Directly set headers on the response after invocation of the next entity in the filter chain.

Parameters:

$request: the Servlet::ServletRequest object that contains the client's request
$response: the Servlet::ServletResponse object that contains the servlet's response
$chain: the Servlet::FilterChain through which the request and response are passed

Throws:

Servlet::ServletException: if an exception occurs while performing the filtering task

getFilterConfig(): Returns the Servlet::FilterConfig object for this filter
setFilterConfig($config): Set the config object for this filter
Parameters:

$config: the Servlet::FilterConfig object for this filter

AUTHOR

Brian Moseley, bcm@maz.org

POD ERRORS

Hey! The above document had some coding errors, which are explained below: