xml::sax::tap(3pm) [debian man page]

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

NAME

       XML::SAX::Tap - Tap a pipeline of SAX processors

SYNOPSIS

	   use XML::SAX::Machines qw( Pipeline Tap ) ;

	   my $m = Pipeline(
	       "UpstreamFilter",
	       Tap( "My::Reformatter", *STDERR ),
	       "DownstreamFilter",
	   );

	   my $m = Pipeline(
	       "UpstreamFilter",
	       Tap( "| xmllint --format -" ),
	       "DownstreamFilter",
	   );

DESCRIPTION

       XML::SAX::Tap is a SAX machine that passes each event it receives on to a brach handler and then on down to it's main handler.  This allows
       debugging output, logging output, validators, and other processors (and machines, of course) to be placed in a pipeline.  This differs from
       XML::Filter::Tee, XML::Filter::SAXT and XML::SAX::Distributer in that a tap is also a pipeline; it contains the processoring that handles
       the tap.

       It's like XML::Filter::Tee in that the events are not buffered; each event is sent first to the tap, and then to the branch (this is
       different from XML::SAX::Dispatcher, which buffers the events).

       It's like XML::SAX::Pipeline in that it contains a series of processors in a pipeline; these comprise the "tapping" processors:

		   +----------------------------------------------+
		   |		      Tap instance		  |
		   |						  |
		   |  Intake					  |
		   |  +-----+	 +---------+	    +---------+   |
	upstream --+->| Tee |--->| Stage_0 |--...-->| Stage_N |   |
		   |  +-----+	 +---------+	    +---------+   |
		   |	     					  |
		   |	       			 Exhaust  |
		   |	       +----------------------------------+--> downstream
		   |						  |
		   +----------------------------------------------+

       The events are not copied, since they may be data structures that are difficult or impossibly to copy properly, like parts of a C-based DOM
       implementation.

       Events go to the tap first so that you can validate events using a tap that throws exceptions and they will be acted on before the tap's
       handler sees them.

       This machine has no "Exhaust" port (see XML::SAX::Machine for details about "Intake" and "Exhaust" ports).

METHODS

       new
	       my $tap = XML::SAX::Tap->new( @tap_processors, \%options );

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, as you choose.

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

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)