Answer to http://jeditoolkit.com/2012/03/21/protocol-based-polymorphism.html#comment-474842550

example.js

// module: plugin-manager.js

var installable = require('./installable')
var events = require('./event-protocol')

function getPlugin() { /* ... */ }
function getDependents() { /* ... */ }

exports.start = function(plugin) {
   // start all dependencies
   plugin.dependencies.forEach(function(id) {
      exports.start(getPlugin(id))
   })

   // notify that plugin is going to be started.
   events.on(plugin, 'before:start', { ... })
   // start an actual plugin!
   installable.on(plugin)
   // notify that plugin was started.
   events.emit(plugin, 'after:start', { ... })

   // track plugin stops so we can unload dependents
   events.once(plugin, 'before:stop', function onstop() {
      // stop all the plugins that depend on this one.
      getDependents(plugin).forEach(exports.stop)
   })
}

exports.stop = function(plugin) {
   events.emit(plugin, 'before:stop', {... })
   installable.off(plugin)
   events.emit(plugin, 'after:stop', { ... })
}

BTW to be completely fare in reality I would have defined Plugin type where I would have implemented custom on / off that would have emitted events, but anyway I think this illustrates how two protocols may be used with a same type.