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.

To see what is being dispatched within a pipeline dispatch set the pipeline's debug value to true.

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

The Pipeline class inherits from the Pipeline::Segment class and therefore also has any additional methods that its superclass may have.

init( @_ )

Things to do at construction time. If you do override this, it will often be fairly important that you call $self->SUPER::init(@_) to make sure that the setup is done correctly. Returns itself on success, undef on failure.

add_segment( LIST )

Adds a segment or segments to the pipeline. Returns itself.

get_segment( INTEGER )

Returns the segment located at the index specified by INTEGER

del_segment( INTEGER )

Deletes and returns the segment located at the index specified by INTEGER

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.

cleanups()

Returns the cleanup pipeline. This is a pipeline in and of itself, and all the methods you can call on a pipeline can also be called on this.

cleanup()

Calls the dispatch method on the cleanup pipeline.

segments( [ value ] )

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

debug_all( value )

Sets debug( value ) recursively for each segment in this pipeline.

SEE ALSO

Pipeline::Segment, Pipeline::Store, Pipeline::Store::Simple Pipeline::Production

AUTHORS

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

COPYRIGHT

Copyright 2003 Fotango Ltd. Licensed under the same terms as Perl itself.