NoFlo is an implementation of flow-based programming for JavaScript running on both Node.js and the browser. From WikiPedia:
In computer science, flow-based programming (FBP) is a programming paradigm that defines applications as networks of "black box" processes, which exchange data across predefined connections by message passing, where the connections are specified externally to the processes. These black box processes can be reconnected endlessly to form different applications without having to be changed internally. FBP is thus naturally component-oriented.
Developers used to the Unix philosophy should be immediately familiar with FBP:
This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface.
It also fits well in Alan Kay's original idea of object-oriented programming:
I thought of objects being like biological cells and/or individual computers on a network, only able to communicate with messages (so messaging came at the very beginning -- it took a while to see how to do messaging in a programming language efficiently enough to be useful).
NoFlo has been written in CoffeeScript for simplicity. The system is heavily inspired by J. Paul Morrison's book Flow-Based Programming.
Read more at http://noflojs.org/.
Suitability
NoFlo is not a web framework or a UI toolkit. It is a way to coordinate and reorganize data flow in any JavaScript application. As such, it can be used for whatever purpose JavaScript can be used for. We know of NoFlo being used for anything from building web servers and build tools, to coordinating events inside GUI applications, driving robots, or building Internet-connected art installations.
Tools and ecosystem
NoFlo itself is just a library for implementing flow-based programs in JavaScript. There is an ecosystem of tools around NoFlo and the fbp protocol that make it more powerful. Here are some of them:
- Flowhub -- browser-based visual programming IDE for NoFlo and other flow-based systems
- noflo-nodejs -- command-line interface for running NoFlo programs on Node.js
- MsgFlo -- for running NoFlo and other FBP runtimes as a distributed system
- fbp-spec -- data-driven tests for NoFlo and other FBP environments
- flowtrace -- tool for retroactive debugging of NoFlo programs. Supports visual replay with Flowhub
See also the list of reusable NoFlo modules on NPM.
Requirements and installing
NoFlo is available for Node.js via NPM, so you can install it with:
$ npm install noflo --save
You can make a browser build of NoFlo using component.io. The grunt-noflo-browser plugin makes this easy.
Installing from Git
NoFlo requires a reasonably recent version of Node.js, and some npm packages. Ensure you have the grunt-cli
package installed (grunt
command should be available on command line) and NoFlo checked out from Git. Build NoFlo with:
$ grunt build
You can also build NoFlo only for the desired target platform with either grunt build:nodejs or grunt build:browser.
Then you can install everything needed by a simple:
$ npm link
NoFlo is available from GitHub under the MIT license.
Changes
Please refer to the Release Notes and the CHANGES.md document.
Usage
Please refer to http://noflojs.org/documentation/. For visual programming with NoFlo, see http://flowhub.io/documentation/.
Development
NoFlo development happens on GitHub. Just fork the main repository, make modifications and send a pull request.
We have an extensive suite of tests available for NoFlo. Run them with:
$ grunt test
or:
$ npm test
Platform-specific tests
By default, the tests are run for both Node.js and the browser. You can also run only the tests for a particular target platform:
$ grunt test:nodejs
or:
$ grunt test:browser
Running tests automatically
The build system used for NoFlo is also able to watch for changes in the filesystem and run the tests automatically when something changes. To start the watcher, run:
$ grunt watch
To quit thew watcher, just end the process with Ctrl-C.
Discussion
There is an IRC channel #fbp
on FreeNode, and questions can be posted with the noflo
tag on Stack Overflow. See http://noflojs.org/support/ for other ways to get in touch.