invoice petri g.js

// Loosely-formed runtime implementation of following action scheme:
// http://www.site.uottawa.ca/~bochmann/ELG7187C/CourseNotes/BehaviorModeling/Petri-nets/Orders%20-%20activity%20diagram.jpg

// async properties, which need some kind of outside world interaction to fill up 
// - order.accepted - decided by admin
// - order.invoice - an object that holds details of payment request
// - order.payment - details of fulfilled payment
// - order.shipment - details of fulfilled shipment

// variables that can be mutated freely in runtime
// - order.accepted
// - order.trusted

// In code:       In Petri:
// - Array/Scope  - Subnet
// - Object       - Tokens
// - Key          - Place
// - Observer     - Transition
// - Dependency   - Ark

// The G language deals with asynchronicity of transitions,
// propagating changes in steps, unrolling and migrating effects


// For each entry in `app.incoming_orders`
var IncomingOrder = {
  // Auto-accept trusted orders
  'trusted == true': function() {
    this.set('accepted', true);
  },
  // Request administrator validation
  'trusted == false': function() {
    this.set('accepted', this.prompt('Approval'))
  },
  // Close invalid orders
  'accepted == false': function() {
    this.set('closed', true);
  },
  // Send invoice if order is valid
  'accepted == true': function() {
    this.set('invoice', this.prompt('Invoice'))
  },
  // When invoice is sent, request for payment
  'invoice': function() {
    this.set('payment', this.prompt('Payment'));
  },
  // Ship goods right after invoice for trusted orders
  'invoice && trusted == true && accepted == true': function() {
    this.set('shipment', this.prompt('Shipment'))
  },
  // Ensure shipment is requested when payment is received 
  'payment': function() {
    this.set('shipment', this.prompt('Shipment'))
  },
  // Once both shipment and payment is complete, close order
  'shipment && payment': function() {
    this.set('closed', true);
  }
}

var InvoicePetri = new G.Petri({
  Order: {
    collection: 'orders',

    attributes: {
      title: String,
      description: String,

      closed: false,
      trusted: false,
      accepted: false
    },

    scopes: {
      incoming: {
        condition: 'closed == false',
        network: IncomingOrder
      },
      closed: {
        condition: 'closed == true && accepted == false'
      },
      fulfilled: {
        condition: 'closed == true && accepted == true'
      }
    }
  }
})