NAME
    Apache::OutputChain - chain stacked Perl handlers

SYNOPSIS
    Inherit from this module to put a new one into the chain.

DESCRIPTION
    This module allows chaining perl handlers in Apache, which enables to
    make filter modules that take output from previous handlers, make some
    modifications, and pass the output to the next handler.

    I will try to explain how this module works, because I hope you could
    help me to make it better and mature.

    When the *handler* function is called, it checks if it gets a reference
    to a class. If this is true, the this function was called from some
    other handler that wants to be put into the chain. If not, it's probably
    an initialization (first call) of this package and we will supply name
    of this package.

    Now we check, where is STDOUT tied. If it is Apache, we are the first
    one trying to be put into the chain. If it is not, there is somebody in
    the chain already. We call tie on the STDOUT, steal it from anybody who
    had it before -- either Apache or the other class.

    When later anybody prints into STDOUT, it will call function *PRINT* of
    the first class in the chain (the last one that registered). If there is
    not other class behind, the *print* method of Apache will be called. If
    this is not the last user defined handler in the chain, we will call
    *PRINT* method of the next class.

SEE ALSO
    Apache::GzipChain by Andreas Koenig, koenig@kulturbox.de for module that
    gzips the output on the fly.

AUTHOR
    (c) 1997 Jan Pazdziora, adelton@fi.muni.cz

    at Faculty of Informatics, Masaryk University, Brno