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Workflow::Config - Parse configuration files for the workflow components


This documentation describes version 1.12 of this package


 # Reference multiple files
 my $parser = Workflow::Config->new( 'xml' );
 my @config = $parser->parse(
     'action', 'workflow_action.xml', 'other_actions.xml'
 # Read in one of the file contents from somewhere else
 my $xml_contents = read_contents_from_db( 'other_actions.xml' );
 my @config = $parser->parse(
     'action', 'workflow_action.xml', \$xml_contents
 # Reference multiple files of mixed types
 my @action_config = Workflow::Config->parse_all_files(
     'action', 'my_actions.xml', 'your_actions.perl'


Read in configurations for the various workflow components. Currently the class understands XML (preferred) and serialized Perl data structures as valid configuration file formats. (I tried to use INI files but there was too much deeply nested information. Sorry.)


parse_all_files( $workflow_config_type, @files )

Runs through each file in @files and processes it according to the valid


Creating Your Own Parser

If you want to store your configuration in a different format you can create your own parser. All you need to do is:

  1. subclass Workflow::Config

  2. implement the required methods (listed below)

  3. register your parser with Workflow::Config.

For instance, if you wanted to use YAML for configuration files you would do something like:

 # just a convention, you can use any namespace you want
 package Workflow::Config::YAML;
 use strict;

 # Requirement 1: Subclass Workflow::Config
 use base qw( Workflow::Config );
 # Requirement 2: Implement required methods
 sub parse { ... }

The third requirement is registration, which just tells Workflow::Config which parser to use for a particular type. To do this you have two options.

Registration option one

Register yourself in your own class, adding the following call anywhere the end:

 # Option 1: Register ourselves by name
 Workflow::Config->register_factory_type( yaml => 'Workflow::Config::YAML' );

Now you just need to include the configuration class in your workflow invocation script:

 use strict;
 use Workflow::Factory qw( FACTORY );
 use Workflow::Config::YAML; # <-- brings in the registration

Registration option two

You can also just explicitly add the registration from your workflow invocation script:

 use strict;
 use Workflow::Factory qw( FACTORY );
 use Workflow::Config;
 # Option 2: explicitly register your configuration parser
 Workflow::Config->register_factory_type( yaml => 'Workflow::Config::YAML' );

Whichever one you choose you can now parse (in this example) YAML files alongside the built-in parsers for XML and Perl files:

     workflow  => 'workflow.yaml',
     action    => [ 'my_actions.yaml', 'other_actions.xml' ],
     validator => 'validators.yaml',
     condition => [ 'my_conditions.yaml', 'other_conditions.xml' ]
     persister => 'persister.perl',

Inherited Methods

new( $parser_type )

Instantiates an object of the correct type -- see Class::Factory for how this is implemented:

 # Parser of type 'Workflow::Config::XML'
 my $xml_parser  = Workflow::Config->new( 'xml' );
 # Parser of type 'Workflow::Config::Perl
 my $perl_parser = Workflow::Config->new( 'perl' );

is_valid_config_type( $config_type )

Returns true if $config_type is a valid configuration type, false if not. Valid configuration types are: 'action', 'condition', 'validator', 'workflow'.


Returns list of strings representing the valid configuration types.

get_config_type_tag( $class, $type )

Returns string representing a valid configuration type, looking up the type parameter in a lookuptable defined in Workflow::Config class.

Required Object Methods

parse( $workflow_config_type, @items )

Parse each item in @items to a hash reference based on the configuration type $config_type which must pass the is_valid_config_type() test. An 'item' is either a filename or a scalar reference with the contents of a file. (You can mix and match as seen in the SYNOPSIS.)

Should throw an exception if:

  • You pass an invalid workflow configuration type. Valid workflow configuration types are registered in Workflow::Config and are available from get_valid_config_types(); you can check whether a particular type is valid with is_valid_config_type(). (See above for descriptions.)

  • You pass in a file that cannot be read or parsed because of permissions, malformed XML, incorrect Perl data structure, etc. It does not do a validation check (e.g., to ensure that every 'action' within a workflow state has a 'resulting_state' key).

Returns: one hash reference for each member of @items


This gives you an idea of the configuration information in the various workflow pieces:


      type          $
      description   $
      persister     $
      initial_state $
      observer    \@
          sub           $
          class         $
      state       \@
          name          $
          description   $
          action        \@
              name            $
              resulting_state $
              condition       \@
                  name              $
  • the 'type' and 'description' keys are at the top level

  • the 'extra_data' key holds an array of zero or more hashrefs with 'table', 'field', 'class' and 'context' keys

  • 'initial_state' key holds a string declaring the name of the initial state. by default, this value is 'INIITAL'.

  • 'state' key holds array of one or more 'state' declarations; one of them must be 'INITIAL' (or the value of initial_state, if it's defined)

  • each 'state' declaration holds 'description' and 'name' keys and multiple 'action' declarations

  • each 'action' declaration holds 'name' and 'resulting_state' keys and may hold a 'condition' key with one or more named conditions


     condition \@
        name  $
        class $
        param \@
            name  $
            value $
  • array of one or more hashrefs with 'name' and 'class' keys


     validator \@
        name  $
        class $
        param \@
            name  $
            value $
  • array of one or more hashrefs with 'name' and 'class' keys, plus possibly one or more 'param' hashrefs each with 'name' and 'value' keys


    action \@
       name  $
       field \@
          name         $
          is_required  yes|no
          type         $
          source_list  \@ of $
          source_class $
          param        \@
              name  $
              value $
       validator \@
           name $
           arg  \@
               value $
  • array of one or more action hashrefs with 'name', 'class' and 'description' keys

  • each 'action' may have zero or more values used to fill it; each value has a 'name', 'description' and 'necessity' ('required' or 'optional')

  • each 'action' may have any number of 'param' hashrefs, each with 'name' and 'value'

  • each 'action' may have any number of 'validator' hashrefs, each with a 'name' key and array of 'arg' declarations


   extra_table   $
   extra_field   $
   extra_class   $
   extra_context $


Copyright (c) 2003-2004 Chris Winters. All rights reserved.

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


Chris Winters <chris@cwinters.com>