NoFlo API

NoFlo - Flow-Based Programming for JavaScript
(c) 2013-2018 Flowhub UG
(c) 2011-2012 Henri Bergius, Nemein
NoFlo may be freely distributed under the MIT license

NoFlo is a Flow-Based Programming environment for JavaScript. This file provides the main entry point to the NoFlo network.

Find out more about using NoFlo from http://noflojs.org/documentation/

/* eslint-disable
    no-param-reassign,
    import/first
*/

Main APIs

Graph interface

fbp-graph is used for instantiating FBP graph definitions.

import { graph } from 'fbp-graph';

Network instantiation

This function handles instantiation of NoFlo networks from a Graph object. It creates the network, and then starts execution by sending the Initial Information Packets.

const network = await noflo.createNetwork(someGraph, {});
console.log('Network is now running!');

It is also possible to instantiate a Network but delay its execution by giving the third delay option. In this case you will have to handle connecting the graph and sending of IIPs manually.

noflo.createNetwork(someGraph, {
  delay: true,
})
  .then((network) => network.connect())
  .then((network) => network.start())
  .then(() => {
    console.log('Network is now running!');
  });

Network options

It is possible to pass some options to control the behavior of network creation:

baseDir: (default: cwd) Project base directory used for component loading
componentLoader: (default: NULL) NoFlo ComponentLoader instance to use for the network. New one will be instantiated for the baseDir if this is not given.
delay: (default: FALSE) Whether the network should be started later. Defaults to immediate execution
flowtrace: (default: NULL) Flowtrace instance to create a retroactive debugging trace of the network run.
subscribeGraph: (default: FALSE) Whether the network should monitor the underlying graph for changes

Options can be passed as a second argument before the callback:

noflo.createNetwork(someGraph, options, callback);

The options object can also be used for setting ComponentLoader options in this network.

import { Network } from './Network';
import { LegacyNetwork } from './LegacyNetwork';
import { deprecated } from './Platform';

export {
  graph,
  Graph,
  journal,
  Journal,
} from 'fbp-graph';

Platform detection

NoFlo works on both Node.js and the browser. Because some dependencies are different, we need a way to detect which we’re on.

export { isBrowser } from './Platform';

Component Loader

The ComponentLoader is responsible for finding and loading NoFlo components. Component Loader uses fbp-manifest to find components and graphs by traversing the NPM dependency tree from a given root directory on the file system.

export { ComponentLoader } from './ComponentLoader';

Component baseclasses

These baseclasses can be used for defining NoFlo components.

export { Component } from './Component';

NoFlo ports

These classes are used for instantiating ports on NoFlo components.

export { InPorts, OutPorts } from './Ports';

export { default as InPort } from './InPort';
export { default as OutPort } from './OutPort';

NoFlo sockets

The NoFlo internalSocket is used for connecting ports of different components together in a network.

import * as internalSocket from './InternalSocket';

export { internalSocket };

Information Packets

NoFlo Information Packets are defined as “IP” objects.

export { default as IP } from './IP';

/**
 * @callback NetworkCallback
 * @param {Error | null} err
 * @param {Network|LegacyNetwork} [network]
 */

/**
 * @typedef CreateNetworkOptions
 * @property {boolean} [subscribeGraph] - Whether the Network should monitor the graph
 * @property {boolean} [delay] - Whether the Network should be started later
 */

/**
 * @typedef { CreateNetworkOptions & import("./BaseNetwork").NetworkOptions} NetworkOptions
 */

/**
 * @param {import("fbp-graph").Graph} graphInstance - Graph definition to build a Network for
 * @param {NetworkOptions} options - Network options
 * @param {NetworkCallback} [callback] - Legacy callback for the created Network
 * @returns {Promise<Network|LegacyNetwork>}
 */
export function createNetwork(graphInstance, options, callback) {
  if (typeof options !== 'object') {
    options = {};
  }
  if (typeof options.subscribeGraph === 'undefined') {
    options.subscribeGraph = false;
  }

Choose legacy or modern network based on whether graph subscription is needed

  const NetworkType = options.subscribeGraph ? LegacyNetwork : Network;
  const network = new NetworkType(graphInstance, options);

Ensure components are loaded before continuing

  const promise = network.loader.listComponents()
    .then(() => {
      if (options.delay) {

In case of delayed execution we don’t wire it up

        return Promise.resolve(network);
      }
      const connected = /** @type {Promise<Network|LegacyNetwork>} */ (network.connect());
      return connected.then(() => network.start());
    });
  if (callback) {
    deprecated('Providing a callback to NoFlo.createNetwork is deprecated, use Promises');
    promise.then((nw) => {
      callback(null, nw);
    }, callback);
  }
  return promise;
}

Starting a network from a file

It is also possible to start a NoFlo network by giving it a path to a .json or .fbp network definition file.

noflo.loadFile('somefile.json', {})
  .then((network) => {
    console.log('Network is now running!');
  });

/**
 * @param {string} file
 * @param {NetworkOptions} options - Network options
 * @param {any} [callback] - Legacy callback
 * @returning {Promise<Network>}
 */
export function loadFile(file, options, callback) {
  const promise = graph.loadFile(file)
    .then((graphInstance) => createNetwork(graphInstance, options));
  if (callback) {
    deprecated('Providing a callback to NoFlo.loadFile is deprecated, use Promises');
    promise.then((network) => {
      callback(null, network);
    }, callback);
  }
  return promise;
}

Saving a network definition

NoFlo graph files can be saved back into the filesystem with this method.

/**
 * @param {graph.Graph} graphInstance
 * @param {string} file
 * @param {any} [callback] - Legacy callback
 * @returning {Promise<string>}
 */
export function saveFile(graphInstance, file, callback) {
  return graphInstance.save(file, callback);
}

Embedding NoFlo in existing JavaScript code

The asCallback helper provides an interface to wrap NoFlo components or graphs into existing JavaScript code.

// Produce an asynchronous function wrapping a NoFlo graph
var wrapped = noflo.asCallback('myproject/MyGraph');

// Call the function, providing input data and a callback for output data
wrapped({
  in: 'data'
}, function (err, results) {
  // Do something with results
});

export { asCallback, asPromise } from './AsCallback';

Generating components from JavaScript functions

The asComponent helper makes it easy to expose a JavaScript function as a NoFlo component. All input arguments become input ports, and the function’s result will be sent to either out or error port.

exports.getComponent = function () {
  return noflo.asComponent(Math.random, {
    description: 'Generate a random number',
  });
};

export { asComponent } from './AsComponent';

This page contains documentation generated automatically from NoFlo's NoFlo.js file.

API Documentation