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The Rules
• Rules is a module usually used to automate actions on Drupal site
• Allows site administrator to define conditionally executed actions based
on occurring events, known as reactive or Event-Condition-Action
(ECA) rules
• Rules is an engine for automating actions in Drupal
– Rules can react to events occurring on Drupal site, such as a user logging in or a node
being submitted
– it can perform customized follow-up actions such as redirecting to a certain page or
setting field values
• Rules is also a framework used by other modules
– allowing other modules to expose user-reconfigurable components with sets of actions
and conditions
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Event Condition Action (1)
• Event
– specifies the signal that triggers the invocation of the rule
• Action
– consists of updates or invocation on the data
• Example:
– When “a user has logged in” “send an email to a user”
– When “content has been viewed” “unpublish content”
– When “content has been updated” “notify the content author”
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Picture: https://drupal.org/files/drupal_EA.png
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Event Condition Action (2)
• Condition
– a logical test that, if satisfied to true, causes the action to be carried out.
• Example:
– When “content has been updated”:
• If “content author different than the acting user” “notify the content author”
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Picture: https://drupal.org/files/drupal_ECA.png
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Features
• To react upon any event with custom conditions and actions
• Allow functionality to be re-used via components (sets of Rules
configuration)
• Scheduling system that allows scheduling any components/action
• Sharing Rules configuration by using the import/export feature
• Makes use of caching routines to speedup rule evaluation
• Rules 2.x:
– improved APIs
– a new admin GUI
– parameter configuration via simple data selection (i.e. “node:author” as argument)
– loops and lists (i.e loop over the list of tags)
– improved debug log
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Integration (1)
• Web Service Client
– provides an interface to consume external web services.
• Rules HTTP Client
– adds an action wrapping of drupal_http_request to use Rules for making http requests.
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Integration (4)
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• Use case: Distributed Editorial Workflow [Ref. vi]
• Separate editorial back-end site and front-ends serving the content to
the public.
– Use Rules web hooks (drupal.org/project/rules_web_hooks) on the editorial back-end
– the front-ends react on these hooks in order to locally create and publish the content
Picture from [Ref. vi]
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Conclusion
• Rules provides capability to react on events automatically
• The reaction could be toward the local data and to remote data (using
additional modules)
• Rules as a framework could be extended to add more functionality for
Action (i.e. request HTTP data, access a Web Service) and Event (i.e.
react to an Event on remote Drupal site)
• Current integration are mostly for the Action part, only few for the Event
part
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References
i. Rules, https://drupal.org/project/rules
ii. Rules Documentation Handbook,
https://drupal.org/documentation/modules/rules
iii. Rules HTTP Client, https://drupal.org/project/rules_http_client
iv. Web service client, https://drupal.org/project/wsclient
v. Rules Web Hooks, https://drupal.org/project/rules_web_hooks
vi. Wolfgang Ziegler, “Event-Condition-Action rules for distributed content
management”, Master Thesis, TU Wien, 2010
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