Composer Module

The composer Node.js module makes it possible define, deploy, and invoke compositions.

Installation

To install the composer module, use the Node Package Manager:

npm install @ibm-functions/composer

To take advantage of the compose command, it may be useful to install the module globally as well (-g option).

Example

The samples/node-demo.js file illustrates how to define, deploy, and invoke a composition using node:

// require the composer module
const composer = require('@ibm-functions/composer')

// define the composition
const composition = composer.if(
    composer.action('authenticate', { action: function ({ password }) { return { value: password === 'abc123' } } }),
    composer.action('success', { action: function () { return { message: 'success' } } }),
    composer.action('failure', { action: function () { return { message: 'failure' } } }))

// instantiate OpenWhisk client
const wsk = composer.openwhisk({ ignore_certs: true })

wsk.compositions.deploy(composition, 'demo') // deploy composition
    .then(() => wsk.actions.invoke({ name: 'demo', params: { password: 'abc123' }, blocking: true })) // invoke composition
    .then(({ response }) => console.log(JSON.stringify(response.result, null, 4)), console.error)

node samples/node-demo.js

{
    "message": "success"
}

Alternatively, the compose command can deploy compositions and the OpenWhisk CLI can invoke compositions. See COMPOSE.md for details.

Combinator methods

The composer object offers a number of combinator methods to define composition objects, e.g., composer.if. Combinators are documented in COMBINATORS.md.

Deployment

The composer object offers an extension to the OpenWhisk Client for Javascript that supports deploying compositions.

OpenWhisk method

A client instance is obtained by invoking composer.openwhisk([options]), for instance with:

const wsk = composer.openwhisk({ ignore_certs: true })

The specific OpenWhisk deployment to use may be specified via the optional options argument, environment variables, or the OpenWhisk property file. Options have priority over environment variables, which have priority over the OpenWhisk property file. Options and environment variables are documented here. The default path for the whisk property file is $HOME/.wskprops. It can be altered by setting the WSK_CONFIG_FILE environment variable.

The composer module adds to the OpenWhisk client instance a new top-level category named compositions with a method named deploy.

Deploy method

wsk.deploy(composition, [name]) deploys the composition composition, giving name name to the corresponding conductor action. More precisely, it successively deploys all the actions and compositions defined in composition as well as composition itself.

The compositions are encoded into conductor actions prior to deployment. In other words, the deploy method deploys one or several actions.

The deploy method returns a successful promise if all the actions were deployed successfully, or a rejected promise otherwise. In the later, the state of the various actions is unknown.

The deploy method deletes the deployed actions before recreating them if necessary. As a result, default parameters, limits, and annotations on preexisting actions are lost.

The name argument may be omitted if the composition consists of a single action invocation. In this case, deploy method only deploys the actions and compositions whose definitions are nested inside composition.

Invoke, Update, and Delete methods

Since compositions are deployed as conductor actions, other management tasks for compositions can be achieved by invoking methods of wsk.actions, for instance:

wsk.actions.delete('demo')

Updating or deleting a conductor action only affect the action itself. It does not affect any other action deployed as part of the composition.