XML::SAX::Pipeline(3pm) 				User Contributed Perl Documentation				   XML::SAX::Pipeline(3pm)

NAME

       XML::SAX::Pipeline - Manage a linear pipeline of SAX processors

SYNOPSIS

	   use XML::SAX::Machines qw( Pipeline );   ## Most common way
	   use XML::Fitler::Foo;

	   my $m = Pipeline(
	       XML::Filter::Foo->new,  ## Create it manually
	       "XML::Filter::Bar",     ## Or let Pipeline load & create it
	       "XML::Filter::Baz",
	       {
		   ## Normal options
		   Handler => $h,
	       }
	   );

	   ## To choose the default parser automatically if XML::Filter::Foo
	   ## does not implement a parse_file method, just pretend the Pipeline
	   ## is a parser:
	   $m->parse_file( "blah" );

	   ## To feed the pipeline from an upstream processor, treat it like
	   ## any other SAX filter:
	   my $p = Some::SAX::Generator->new( Handler => $m );

	   ## To read a file or the output from a subprocess:
	   my $m = Pipeline( "<infile.txt" );
	   my $m = Pipeline( "spew_xml |" );

	   ## To send output to a file handle, file, or process:
	   my $m = Pipeline( ...,  *STDOUT );
	   my $m = Pipeline( ..., ">outfile.txt" );
	   my $m = Pipeline( ..., "| xmllint --format -" );

DESCRIPTION

       An XML::SAX::Pipeline is a linear sequence SAX processors.  Events passed to the pipeline are received by the "Intake" end of the pipeline
       and the last filter to process events in the pipeline passes the events out the "Exhaust" to the filter set as the pipeline's handler:

	  +-----------------------------------------------------------+
	  |		    An XML:SAX::Pipeline		      |
	  |    Intake						      |
	  |   +---------+    +---------+	 +---------+  Exhaust |
	--+-->| Stage_0 |--->| Stage_1 |-->...-->| Stage_N |----------+----->
	  |   +---------+    +---------+	 +---------+	      |
	  +-----------------------------------------------------------+

       As with all SAX machines, a pipeline can also create an ad hoc parser (using XML::SAX::ParserFactory) if you ask it to parse something and
       the first SAX processer in the pipeline can't handle a parse request:

	  +-------------------------------------------------------+
	  |		    An XML:SAX::Pipeline		  |
	  |		    Intake				  |
	  | +--------+	 +---------+	     +---------+  Exhaust |
	  | | Parser |-->| Stage_0 |-->...-->| Stage_N |----------+----->
	  | +--------+	 +---------+	     +---------+	  |
	  +-------------------------------------------------------+

       or if you specify an input file like so:

	  my $m = Pipeline(qw(
	      <input_file.xml
	      XML::Filter::Bar
	      XML::Filter::Baz
	  ));

       Pipelines (and machines) can also create ad hoc XML::SAX::Writer instances when you specify an output file handle (as shown in the
       SYNOPSIS) or an output file:

	  my $m = Pipeline(qw(
	      XML::Filter::Bar
	      XML::Filter::Baz
	      >output_file.xml
	  ));

       And, thanks to Perl's magic open (see perlopentut), you can read and write from processes:

	  my $m = Pipeline(
	      "gen_xml.pl |",
	      "XML::Filter::Bar",
	      "XML::Filter::Baz",
	      "| consume_xml.pl",
	  );

       This can be used with an XML::SAX::Tap to place a handy debugging tap in a pipeline (or other machine):

	  my $m = Pipeline(
	      "<input_file.xml"
	      "XML::Filter::Bar",
	      Tap( "| xmllint --format -" ),
	      "XML::Filter::Baz",
	      ">output_file.xml",
	  );

METHODS

       See XML::SAX::Machine for most of the methods.

       new
	       my $pipeline = XML::SAX::Pipeline->new( @processors, \%options );

	   Creates a pipeline and links all of the given processors together.  Longhand for Pipeline().

AUTHOR

	   Barrie Slaymaker <barries@slaysys.com>

COPYRIGHT

	   Copyright 2002, Barrie Slaymaker, All Rights Reserved.

       You may use this module under the terms of the Artistic, GNU Public, or BSD licenses, your choice.

perl v5.10.0							    2009-06-11						   XML::SAX::Pipeline(3pm)