NAME

       XML::SAX::Manifold - Multipass processing of documents

VERSION

       version 0.46

SYNOPSIS

           use XML::SAX::Machines qw( Manifold ) ;

           my $m = Manifold(
               $channel0,
               $channel1,
               $channel2,
               {
                   Handler => $h, ## optional
               }
           );

DESCRIPTION

       XML::SAX::Manifold is a SAX machine that allows "multipass" processing of a document by
       sending the document through several channels of SAX processors one channel at a time.  A
       channel may be a single SAX processor or a pipeline (see XML::SAX::Pipeline).

       The results of each channel are aggregated by a SAX filter that supports the "end_all"
       event, "XML::Filter::Merger" by default.  See the section on writing an aggregator and
       XML::Filter::Merger.

       This differs from XML::Filter::SAXT in that the channels are prioritized and each channel
       receives all events for a document before the next channel receives any events.
       XML::SAX::Manifold buffers all events while feeding them to the highest priority channel
       ($processor1 in the synopsis), and replays them for each lower priority channel one at a
       time.

       The event flow for the example in the SYNOPSIS would look like the following, with the
       numbers next to the connection arrow indicating when the document's events flow along that
       arrow.

          +--------------------------------------------------------+
          |         An XML::SAX::Manifold instance                 |
          |                                                        |
          |               +-----------+                            |
          |            +->| Channel_0 |-+                          |
          |          1/   +-----------+  \1                        |
          |  Intake  /                    \                        |
        1 |  +------+ 2   +-----------+  2 \    +--------+ Exhaust |
        --+->| Dist |---->| Channel_1 |-----*-->| Merger |---------+--> $h
          |  +------+     +-----------+    /    +--------+         |
          |          \3                  3/                        |
          |           \   +-----------+  /                         |
          |            +->| Channel_2 |-+                          |
          |               +-----------+                            |
          +--------------------------------------------------------+

       Here's the timing of the event flows:

          1: upstream -> Dist. -> Channel_0 -> Merger -> downstream
          2:             Dist. -> Channel_1 -> Merger -> downstream
          3:             Dist. -> Channel_2 -> Merger -> downstream

       When the document arrives from upstream, the events all arrive during time period 1 and
       are buffered and also passed through Channel_0 and Channel_0's output is sent to the
       Merger.  After all events have been received (as indicated by an "end_document" event from
       upstream), all events are then played back through Channel_1 and then through Channel_2
       (which also output to the Merger).

       It's the merger's job to assemble the three documents it receives in to one document; see
       XML::Filter::Merger for details.

NAME

       XML::SAX::Manifold - Multipass processing of documents

METHODS

       new
               my $d = XML::SAX::Manifold->new( @channels, \%options );

           Longhand for calling the Manifold function exported by XML::SAX::Machines.

Writing an aggregator.

       To be written.  Pretty much just that "start_manifold_processing" and
       "end_manifold_processing" need to be provided.  See XML::Filter::Merger and it's source
       code for a starter.

AUTHORS

       •   Barry Slaymaker

       •   Chris Prather <chris@prather.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2013 by Barry Slaymaker.

       This is free software; you can redistribute it and/or modify it under the same terms as
       the Perl 5 programming language system itself.