1.4.3 API docs

Publishing modules

NoFlo modules are distributed via the NPM package registry. You can see a list of reusable NoFlo modules using the noflo keyword.

Developers can publish their own NoFlo modules by simply releasing them on NPM. The module can be NoFlo-only, but it is also possible to include NoFlo components and graphs in any NPM module.

Module structure

To provide NoFlo components, an NPM module should provide the following structure:

  • package.json: The module manifest listing dependencies and other package metadata
  • components/: directory used for finding components. Components can be either .coffee or .js files
  • graphs/: directory used for finding graphs. Graphs can be either .json or .fbp files

Both the components/ and graphs/ directory contain subfolders. This is useful for further organization if your module ships many components or graphs.

Publishing your module

Please refer to the NPM documentation on how to publish packages in general.

To make your module discoverable to NoFlo users, it is a good idea to include the noflo keyword in your package.json:

  "keywords": [

The NPM registry can also be used for publishing private modules.

Cross-platform modules

NoFlo components or graphs can either be specific to one platform, or available for both Node.js and the browser. For cross-platform libraries there are some different strategies for dealing with the platform differences. By default NoFlo assumes that each component or graph works in both Node.js and the browser.

There are situations where a component only makes sense for a particular platform. For example, DOM manipulation is typically only useful in the browser, and only Node.js can serve HTTP.

Components that work on both platforms

The ideal setup is that a component would work the same way in both Node.js and the browser.

Since there can be some differences between the environment, including different third-party libraries available, you can perform platform checks at runtime with:

if (noflo.isBrowser()) {
  // Do something specific to the browser environment
} else {
  // Do something specific to Node.js

Platform-specific components

If you have components or graphs that only work on one of the platforms, you can use runtime annotations to tell NoFlo which platform a component works on.

To tell NoFlo that a component works only in the browser, add the following comment to beginning of the source file:

// @runtime noflo-browser

If the component works only on Node.js, use the following comment:

// @runtime noflo-nodejs

The possible values for the @runtime annotations include:

  • noflo-browser for browser-based components
  • noflo-nodejs for Node.js components
  • noflo-gnome for GNOME desktop components
  • microflo for microcontroller components

Aliasing components

If you want to provide the same component interface on multiple platforms, but need different implementations for each, you can use the name annotation to alias a file to a different component name.

For example, if you have a LoadImage component, with platform-specific implementations, you could have:

components/LoadImage-browser.js file:

// @runtime noflo-browser
// @name LoadImage

components/LoadImage-node.js file:

// @runtime noflo-nodejs
// @name LoadImage

Best practices

To make NoFlo modules easy to maintain, it is a good idea to aim for a good test coverage.

When the module has tests, there are useful services to automate parts of the module maintenance work:

  • Travis CI can be used for continuous integration
  • Greenkeeper can send you Pull Requests when any of your module dependencies get updated

Release automation with Travis CI

In addition to running your test suite, Travis CI can be configured to automatically release new versions of your module on NPM whenever you git tag it.

1) Have the required gems installed

$ sudo gem install json
$ sudo gem install travis

2) log into npm

$ npm login

3) copy auth token

$ cat ~/.npmrc | grep _auth

You’ll get ~ ‘//’. copy the part after ‘_authToken=’, in this case it is 12aaeee1-1ee2-101a-1a11-1111aaaa1b23

4) configure travis

$ travis setup npm

enter the information it asks for, the npm API key is the one from step 3.

Bootstrapping modules

For faster setup of new NoFlo modules, we have a grunt-init project scaffold template for NoFlo libraries.

Start by installing grunt-init:

$ npm install -g grunt-init

Then you can clone the grunt-init-noflo template to your local directory:

$ mkdir -p ~/.grunt-init
$ git clone ~/.grunt-init/noflo

After this you can create new NoFlo modules easily. Create an empty directory, and run:

$ grunt-init noflo

The scaffold will ask you some questions. Answer those, and you’ll be all ready for component development, including a continuous integration setup.