Triggers and Rules

Using a Deployment file to bind Trigger parameters

This example builds on the previous Trigger and Rule example and will demonstrate how to use a Deployment File to bind values to a Trigger’s input parameters and apply them against a compatible Manifest File.

Manifest File

Let’s use a variant of the Manifest file from the previous example; however, we will leave the parameters on the ‘meetPerson’ Trigger unbound and having only Type declarations for each.

Example: “Hello world” Action, Trigger and Rule with no Parameter bindings

packages:
  hello_world_package
  ... # Package keys omitted for brevity
    actions:
      hello_world_triggerrule:
        function: src/hello_plus.js
        runtime: nodejs
        inputs:
          name: string
          place: string
          children: integer
          height: float
        outputs:
          greeting: string
          details: string

    triggers:
      meetPerson:
        inputs:
          name: string
          place: string
          children: integer
          height: float

    rules:
      meetPersonRule:
        trigger: meetPerson
        action: hello_world_triggerrule

Deployment file

Let’s create a Deployment file that is designed to be applied to the Manifest file (above) which will contain the parameter bindings (i.e., the values) for the ‘meetPerson’ Trigger.

Example: Deployment file that binds parameters to the ‘`meetPerson`’ Trigger

project:
  packages:
      hello_world_package:
        triggers:
          meetPerson:
            inputs:
              name: Elrond
              place: Rivendell
              children: 3
              height: 1.88

As you can see, the package name ‘hello_world_package’ and the trigger name ‘meetPerson’ both match the names in the corresponding Manifest file.

Deploying

Provide the Manifest file and the Deployment file to the wskdeploy utility:

$ wskdeploy -m docs/examples/manifest_hello_world_triggerrule_unbound.yaml -d docs/examples/deployment_hello_world_triggerrule_bindings.yaml

Triggering

Fire the ‘meetPerson’ Trigger:

$ wsk trigger fire meetPerson

Result

Find the activation ID for the “hello_world_triggerrule’ Action that firing the Trigger initiated and get the results from the activation record:

$ wsk activation list

3a7c92468b4e4170bc92468b4eb170f1 hello_world_triggerrule
afb2c02bb686484cb2c02bb686084cab meetPersonRule
9dc9324c601a4ebf89324c601a1ebf4b meetPerson

$ wsk activation get 3a7c92468b4e4170bc92468b4eb170f1

"result": {
  "details": "You have 3 children and are 1.88 m. tall.",
  "greeting": "Hello, Elrond from Rivendell"
}

Discussion

The ‘hello_world_triggerrule’ Action and the ‘meetPerson’ Trigger in the Manifest file both had input parameter declarations that had no values assigned to them (only Types).
The matching ‘meetPerson’ Trigger in the Deployment file had values bound its parameters.
The wskdeploy utility applied the parameter values (after checking for Type compatibility) from the Deployment file to the matching (by name) parameters within the Manifest file.

Source code

Specification

For convenience, the Actions and Parameters grammar can be found here:

Triggers
Rules