@flowscripter/esm-dynamic-plugins

esm-dynamic-plugins

Plugin framework using ES Modules and Dynamic Import.

Overview

This project provides a Javascript framework for defining plugins which may be dynamically discovered and imported into a running Javascript process.

Key Features

• Universal support for both NodeJS and browser Javascript runtimes
• Dynamic plugin import using Javascript dynamic import
• ES2015 module based
• Written in Typescript

Key Concepts

The framework's key concepts are borrowed from the Eclipse Project's extension framework. The key concepts are:

• A HostApplication instantiates a PluginManager
• The PluginManager provides an ExtensionPointRegister
• The HostApplication can declare ExtensionPoints in the ExtensionPointRegister
• A Plugin provides one or more Extensions for one or more ExtensionPoints
• A Plugin provides an ExtensionDescriptor for each Extension it provides
• A PluginManager scans for and registers Plugins which provide Extensions for the known ExtensionPoints
• A HostApplication uses the PluginManager to query for and select an Extension for a desired ExtensionPoint
• The PluginManager uses an ExtensionFactory declared in an ExtensionDescriptor to instantiate a selected Extension

The following high level class diagram illustrates these relationships:

The following sequence diagram illustrates the key steps for a HostApplication to use a PluginManager for discovery and registration of Plugins:

Once registration has been performed, the HostApplication may query for and instantiate Extensions for known ExtensionPoints:

As ExtensionPoints are simply Javascript classes, for the purposes of testing or validation, it is possible to bypass the framework altogether and import an Extension and use it directly:

Examples

The following example projects are available which all support execution in NodeJS and a browser:

• TypeScript based host application
• TypeScript based plugin
• JavaScript based host application
• JavaScript based plugin

Code Documentation

Typescript documentation

Development

Firstly:

npm install

Note: The warnings regarding peer dependencies are caused by dependencies or sub-dependencies which have yet to update their peer-dependencies. They can safely be ignored.

Build: npm run build

Watch: npm run watch

Test: npm test

Lint: npm run lint

Docs: npm run docs

The following diagram provides an overview of the main classes:

Further Details

Further details on project configuration files and Javascript version support can be found in the template for this project.

Alternatives

• js-plugins - also provides a plugin framework following Eclipse Project's framework. Relies on plugin declarations in package.json instead of Typescript interfaces. Does not support browser or ES2015 modules.
• oclif plugins - very much tied to the Oclif CLI. Relies on available plugins being declared in package.json. Does not support browser or ES2015 modules.

License

MIT © Flowscripter