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1.1.1.1 Keynames

The following is the list of recognized keynames for a TOSCA trigger definition:

Keyname

Required

Type

Description

description

no

description

The optional description string for the named trigger.

event_type

yes

string

The required name of the event type that activates the trigger’s action.

schedule

no

TimeInterval

The optional time interval during which the trigger is valid (i.e., during which the declared actions will be processed).

target_filter

no

event filter

The optional filter used to locate the attribute to monitor for the trigger’s defined condition. This filter helps locate the TOSCA entity (i.e., node or relationship) or further a specific capability of that entity that contains the attribute to monitor.

condition

no

constraint clause

The optional condition which contains an attribute constraint that can be monitored.  Note: this is optional since sometimes the event occurrence itself  is enough to trigger the action.

constraint

no

constraint clause

The optional condition which contains an attribute constraint that can be monitored.  Note: this is optional since sometimes the event occurrence itself  is enough to trigger the action.

period

no

scalar-unit.time

The optional period to use to evaluate for the condition.

evaluations

no

integer

The optional number of evaluations that must be performed over the period to assert the condition exists.

method

no

string

The optional statistical method name to use to perform the evaluation of the condition.[MR1] 

action

yes

operation

The required operation to invoke when the event is triggered and the condition is met (i.e., evaluates to true).

1.1.1.2 Grammar

Trigger definitions have the following grammars:

<trigger_name>:

  description: <trigger_description>

  # TBD: need to separate “simple” and “full” grammar for event type name

  event: <event_type_name>

    type: <event_type_name>

  schedule: <time_interval_for_trigger>

  target_filter:

    <event_filter_definition>

  condition: <attribute_constraint_clause>

    constraint: <attribute_constraint_clause>

    period: <integer> # e.g., 60

    evaluations: <integer> # e.g., 1

    method: <string> # e.g., average

  action:

    <operation_definition>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

  • trigger_name: represents the required symbolic name of the trigger as a string.
  • trigger_description: represents the optional description string for the corresponding trigger_name.
  • event_type_name: represents the required name of the TOSCA Event Type that would be monitored on the identified resource (node). 
  • time_interval_for_trigger: represents the optional time interval that the trigger is valid for.
  • event_filter_definition: represents the optional filter to use to locate the resource (node) or capability attribute to monitor. 
  • attribute_constraint_clause: represents the optional attribute constraint that would be used to test for a specific condition on the monitored resource.
  • operation_definition: represents the required action to take if the event and (optionally) condition are met.

 

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