Author: Bill Erickson
Created on: Dec. 7, 2009
See the description in Dan Scott's Evergreen Workshop
A reference to an action within the ILS. This is how we indicate what types of behaviour we want to react to. Examples include "hold.available" (item became ready for pickup from the holds shelf) and "checkout.due" (circulating item is due).
Module that validates context data prior to reaction. This is critical for supporting delayed reactions. Common examples include "HoldIsAvailable", "CircIsOverdue", and "CircIsOpen".
For developers: The system looks for validator modules in the OpenILS::Application::Trigger::Validator namespace. If they are not found, it searches the Perl library path
Module that defines how the system should respond to actions that match configured hooks. The most common example is "SendEmail".
For developers: The system looks for reactor modules in the OpenILS::Application::Trigger::Reactor namespace. If they are not found, it searches the Perl library path.
Module that performs post-reaction cleanup operations. The system support success cleanups and failure cleanup modules. This type of module is useful for cleaning up temporary files, etc.
The Event Definition is the heart of the action/trigger configuration. It ties together a hook, validator, reactor, cleanup(er), template, and other settings to define a single reaction context. If you said, "I want to set up 7-day overdue email notices", you'd be talking about configuring an event definition.
Under normal circumstances, the hooks, validators, reactors, and cleanup modules will already be in place. All an administrator needs to do is set up the event definition to pull those pieces together. Below is a discussion of the event definition fields and how they are used.
The context library for the event definition. This can be any organization unit in the hierarchy. This value is important because it defines the scope of the event definition. If the Owning Library has descendant org units (e.g. a consortium or a system), actions that occur at all descendant org units are relevant to the event definition. If the owning library is a single branch, then only actions at that branch are relevant. This gives admins the flexibility to define, for example, a single 7-day overdue notice for an entire consortium, or one per system, branch, etc.
Human-friendly name for an event definition. This can be anything as long as it is unique to the owning library. A good rule of thumb for naming an event definition is to summarize the hook, reactor, and delay. For example, "7-Day Courtesy Email Notice".
A reference to the hook (described above)
Event definitions can be turned off by setting the active flag to false.
This value defines the amount of time the system should wait after a target object becomes "relevant" before reacting on that target object. This value is stored in the database as an interval data-type, use compatible input formats. Some examples will help here:
This is the field on the target object that defines the time stamp to use as the base time for calculating the time since the target became relevant or, in the case of looking into the future, the time until the target becomes relevant. This value is used to determine if a given target falls within the configured processing delay.
For checkout.due, the delay context field is the due date. With a 7-day notice, we add 7 days to the due_date to determine if the item is in fact 7 days overdue. For hold.available, the delay field is shelf_time. With a 1-hour delay, the system just adds 1 hour to the shelf_time value to determine if the system has waited long enough before sending the notice.
The field name maps to a <field> entry in the IDL for the target object's class. The field must be a date/time field.
This field is used to group events so they can be reacted upon en masse. The most common example of this is to group by the user field on the target object so that a patron, for example, will only receive 1 email for all items that are 7 days overdue and not 1 per item.
The field name maps to a <field> entry in the IDL for the target object's class.
The validator module to use. To create a custom validator add code/modules to the
OpenILS::Application::Trigger::Validator package and create an entry for this new code in the list of Validators.
The reactor module to use.
The failure cleanup module to use (optional)
The success cleanup module to use (optional)
A string used to distinguish among events that should be run (by the action_trigger_runner.pl script) at different times.
If a site is busy or large enough that all the events typically run overnight won't be able to finish by morning if they're all run in a big lump, or if you have some events that you don't even need to run every night, you can use the granularity field (and the –granularity and –granularity-only options of action_trigger_runner.pl) to group events and selectively run them.
A template toolkit input document, data are specified using the Event Environment and Event Parameters options for the event definition. This template is used, for example, by the SendEmail reactor.
[% USE date %] [% USE Dumper %] [% SET user = target.0.usr %] To: [%- user.email -%] From: Subject: Item Due Reminder Dear [% user.first_given_name %] [% FOR circ IN target %] Title: [%- circ.target_copy.call_number.record.simple_record.title -%] Barcode: [% circ.target_copy.barcode %] Due: [% circ.due_date %] [% END %] [% Dumper.dump(target) %]
Controls which data are available when processing this trigger (Validator, Reactor, Cleanup). Many trigger definitions include usr, target_copy, pickup_lib or target_copy.call_number.record.simple_record. The Event Environment values are paths to objects in the system. This data is stored in action_trigger.environment, bound to action_trigger.event_definition via event_def.
This allows one to define key/value type data which becomes available during the processing of the trigger (Validator, Reactor). These options may be useful when creating custom validators for example. The Parameter Name can match /[\w,\-\.]+/, but just /\w+/ is more practical. The Parameter Value is eval'd on the server side, so they must be stored as valid Perl values. For strings, wrap them in quotes. This data is stored in action_trigger.event_params, also bound by event_def.
When events occur records are created in the action_trigger.event table and these events are processed by the action_trigger_runner.pl script. Usually as a set of cron tasks for the opensrf user.
# General A/T */2 * * * * action_trigger_runner.pl --process-hooks --run-pending # Run Specific Granularity Only 20 20 * * * action_trigger_runner.pl --run-pending --granularity Daily-Active-Report --granularity-only # Just do these hooks 21 21 * * * action_trigger_runner.pl --run-pending --hooks=checkout # Example with Wrapper 4 4 * * * /openils/cron/daily-overdue.sh
It's not uncommon to have dozens of entries in the crontab for Evergreen. One may also want to create create wrapper shell scripts for the action_trigger_runner script to permit in-line documentation or other features. Here is an example.
#!/bin/bash # I'm some documentation on this script! # Run holds available, only the daily-hold granularity /openils/bin/action_trigger_runner.pl \ --debug-stdout \ --verbose \ --run-pending \ --hooks=hold.available \ --granularity=Daily-Hold \ --granularity-only \ >/var/log/atr.log \ 2>/var/log/atr.log logger --id --tag atr "Action Trigger Runner for Daily Available Holds Done"