Tasks

The task construct defines how to perform a goal. This may be to take some action internally, or it could be to delegate the work to another actor via the Paranet.

Just like rules, a task has a goal pattern and statement body. Here is an example of a task defined following our running example of employee onboarding:

task !DoCorporateTraining($employee_id) {
  let $template = Env("CORPORATE_TRAINING_TEMP");
  pncp request employee/send_message($employee_id, $template);
}

This is an example where the task is simply delegated to another actor via the Paranet.

Paraflow Task

One of two types of tasks, the Paraflow task describes how to achieve matching goals as code. Like rules, the task declaration has a goal pattern to describe what goals it applies to. Unlike rules, the task body describes how to achieve the goal procedurally. When the planner matches a specific goal instance to a task, the task body will be executed. The goal will be considered complete once the task body has been executed.

<paraflow-task> : =
  "task" <goal-pattern> [ <cost-clause> ] [ "on" <expression> ] 
  <task-stmt-block>
  [ <catch-block> ]

Goal patterns are described in detail in the Rules section. The task body consists of a list of statements to execute.

<task-stmt-block> := "{" <task-statement> { <task-statement> } "}"
<task-statement> :=
  <let-statement> |
  <rpc-statement> |
  <procedure-call> |
  <pncp-statement> |
  <if-statement> |
  <with-statement> |
  <loop-statement> |
  <transaction-statement> |
  <update-statement> |
  <new-goal-statement> |
  <update-goal-statement> |
  <return-statement> |
  <exception-statement> |
  <retry-statement> |
  <audit-statement> |
  <log-statement>