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Paranet Actors

The following sections describe more advanced usage of the native Paranet support in Paraflow.

Skill Implementation​

The expanded form of the skill declaration offers the additional features:

  • Calculate derived values to be used as parameters to the skill goal
  • Handle questions from the skill requester
  • Handle status messages from the skill requester
  • Handle a canceled request

For example,

skill basic/test($case string) {
  let $t = Now();
  new !Test($case, $t);
} handle {
  question progress -> with !Test(case == $case, $t) {
    pncp answer(message -> "working " + TimeElapsed($t, Now()));
  }
  status { $notice } -> log warn(`requester says $notice`);
  cancel -> {
    log warn(`requester cancel`);
    cancel !Test($case);
  }
}

The start block is executed when a skill request is received and the handle cases are executed when a the corresponding message is received. Note that the skill input parameters are available in handlers. The entire handle block is optional as well as each individual handle case.

Skill Requests​

The expanded form of the delegate declaration offers the additional features:

  • Calculate derived values to be used as parameters to the skill request
  • Ability to do post-processing of the response
  • Handle errors from the skill provider
  • Handle a cancel from the skill provider

For example,

delegate !DoRequest($case) {
  let $deadline = Now() + 5 min;
  let { $answer } = pncp request basic/handler($case, $deadline) in {
    pncp response(result -> "success", $answer);
  }
} handle {
  error { $error } -> pncp response(result -> "failed", $error);
  cancel -> pncp response(result -> "canceled");
}

Questions​

Actors can ask each other questions during the coarse of a skill request. Paraflow actors can ask questions by declaring how a goal maps to a question. Since questions are associated with a active skill request, the goal must be part of a skill-request workflow. The concise form of the question declaration has the following syntax.

<question-declaration> := "question" <goal-pattern> "is" <question-id> <call-bindings> [ "output" <output-clause> ] ";"
<output-clause> := "{" <output-field> [ "," <output-field> ] "}"
<output-field> := <variable> | <field> ":" <variable>

For example,

question !Confirm($name) is sure(message->"Are you sure (y/n)") output { $answer };

The question declaration also has an expanded form which support do some pre- and/or post-processing of the question inputs/outputs. For example,

question !Confirm($case) {
  let { $ok } = pncp question sure(message->"Are you sure (y/n)") in {
    log info("got "+$answer);
  }
}

Skillset Declaration​

Skillsets which are not directly implemented by an actor can be declared in a block of paraflow code. These definitions are registered to the paranet, with the expectation that they are implemented by a different actor from the one defining them. This is especially useful for skills intended to be implemented by human actors.

For example,

type Order {
  id string,
  creator string,
  quantity int
};

# Define skills we can call from this actor, or any other.
skillset "orders@1.0.0" {
  orders/place($id int);
  orders/list($creator string) array[Order];
}