NAME

Pipeline - Generic pipeline interface

SYNOPSIS

  use Pipeline;
  my $pipeline = Pipeline->new();
  $pipeline->add_segment( @segments );
  $pipeline->dispatch();

DESCRIPTION

Pipelines are a mechanism to process data. They are designed to be plugged together to make fairly complex operations act in a fairly straightforward manner, cleanly, and simply.

USING THE PIPELINE MODULE

The usage of the generic pipeline module is fairly simple. You instantiate a Pipeline object by using the new() constructor.

Segments can be added to the pipeline with the add_segment method.

The store that the Pipeline will use can be set by calling the store() method later on. If a store is not set by the time a pipeline is executing then it will use a store of the type Pipeline::Store::Simple

To start the pipeline running call the dispatch() method on your Pipeline object.

WRITING A PIPELINE

INHERITANCE

Pipelines are designed to be inherited from. The inheritance tree is somewhat warped and should look a little like this:

     MySegment --> Pipeline::Segment <--- Pipeline

In other words, everything is a pipeline segment.

METHODS

init()

Things to do at construction time. If you do override this, its will often be fairly important that you call $self->SUPER::init() to make sure that the setup is done correctly.

add_segment( LIST )

Adds a segment or segments to the pipeline.

add_cleanup( LIST )

Adds a segment or segments to the cleanup pipeline, that gets executed after the pipeline has finished.

dispatch()

Starts the pipeline execution, returns the production or undef

dispatch_loop( Pipeline, [ ARRAYREF ] )

The dispatch_loop method performs the processing for the pipeline

dispatch_segment( Pipeline::Segment )

The dispatch_segment method handles the execution of an individual segment object.

cleanup( [ value ] )

cleanup gets and sets the value of the cleanup list. At initialization this is set to an array reference.

pipeline( [ value ] )

pipeline gets and sets the value of the pipeline list. At initialization this is set to an array reference.

store( [ Pipeline::Store ] )

store gets and sets the value of a Pipeline's store. At initialization this is set to a Pipeline::Store::Simple object.

AUTHOR

James A. Duncan <jduncan@fotango.com> Leon Brocard <acme@astray.com>

COPYRIGHT

Copyright 2002 Fotango Ltd. Licensed under the same terms as Perl itself.