NAME
VS::RuleEngine::Loader::XML - Load VS::RuleEngine engine declarations in XML
SYNOPSIS
use VS::RuleEngine::Loader::XML;
my $engine = VS::RuleEngine::Loader::XML->load_file("my_engine.xml");
$engine->run();
my $other_engine = VS::RuleEngine::Loader::XML->load_string($xml);
$other_engine->run();DESCRIPTION
This module provides a mean to load VS::RuleEngine engine declarations from XML.
INTERFACE
CLASS METHODS
- load_file ( PATH )
-
Loads the engine declaration from PATH.
- load_string ( XML )
-
Loads the engine declaration from XML.
XML Document structure
The document root element must be <engine>. Valid children are:
<action> - Declares an action.
<defaults> - Defines a default argument set
<input> - Declares an input.
<output> - Declares an output.
<rule> - Declares a rule.
<ruleset> - Groups a set of rules under a common name.
<run> - Connects a set of rules to an action.
Action, Input, Output and Rule elements
The elements <action>, <input>, <output> and <rule> all have the following mandatory attributes:
- name
-
The name of the entity to define in the engine.
- instanceOf
-
The class that implements the entity and that'll be instansiated when the engine is runned.
- defaults
-
The default arguments to the entity as defined by a previously declared <defaults>. Separate multiple defaults with comma and/or whitespace.
If the class defined by instanceOf implements the method process_xml_loader_args it will be called as a class method with the XML::LibXML::Element-element as only argument. This method must return a list of arguments that will be passed to the constructor for the class when the entity is instansiated.
If no process_xml_loader_args method is available the loader will interpret all children as a hash where the elements name is the key and its text content its value. If a child is an empty element, that is has no children (as in <foo/>) its value will be undef. This hash will be passed to the constructor as a hash reference.
Defaults
By using the tag <defaults> t is possible to declare common arguments that can be reused by multiple entities. Its children will be interpreted as key/value pairs. The required attribute 'name' defines the name for the defaults.
Rulesets
By using the tag <ruleset> it is possible to give a set of rules a shared name that can later be used when binding together rules and actions.
The attribute name is always expected and is used to give the ruleset its name which can be referenced later on by other rulesets or rule<->action mappings.
To specify what rules to include it expects <rule>name of rule</rule and/or <ruleset>name of ruleset</ruleset> elements as children. Any other element will result in an error.
In addition to specifying specific rules or contens of other rulesets it is also possible to include the rules that matches the criteria specified by the attributes:
- rulesMatchingName
-
Include all rules that matches the name by the given Perl5 regular expression.
- rulesOfClass
-
Include all rules which inherits from the given class.
Note, if both attributes above are present it does not create a ruleset with the rule that matches both (i.e a union).
Connecting rules and actions
To connect an action to a rule use the <run> element. It expects the attribute action which must be the name of an already defined action. Which rules to invoke the action on is specified with children of type <rule>name of rule</rule and/or <ruleset>name of ruleset</ruleset>. Any other element will result in an error.
SEE ALSO
BUGS AND LIMITATIONS
Please report any bugs or feature requests to bug-vs-ruleengine-loader-xml@rt.cpan.org, or through the web interface at http://rt.cpan.org.
AUTHOR
Claes Jakobsson <claesjac@cpan.org>
LICENCE AND COPYRIGHT
Copyright (c) 2007 - 2008, Versed Solutions <info@versed.se>. All rights reserved.
This software is released under the MIT license cited below.
The "MIT" License
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.