Create Entity/Aspects JS objects for loaded simulation

[tarelli]

• [x] Create generic node class that every tree node will extend, e.g. Node
• [x] Create JS Entity node class, e.g. EntityNode
• [x] Create JS Aspect node class, e.g. AspectNode
• [x] Identify a JS pattern to instantiate objects of a given prototype

[gidili]

Just to add more detail to this - we need to have a state-tree client side made up of nested entities, each entity having one or more aspects. We need to be able not only to store key-value pairs representing variables names and their values but also to call methods on these entities that will be mapped to the server-side API.

We have a sort of object orientation already for client side objects such as simulation in js - but these are currently a global object we need to be able to instantiate these classes so that we can build up a tree made of instances.

We need to find a suitable framework to do this. If anybody has ideas please share them!

[mlolson]

@gidili I'm not entirely sure if I understand the difference between an entity and an aspect so sorry if I'm missing something, but this seems like it might be a job for backbone associations

This would allow you to define a backbone structure for nested models that looks something like the following:

var AspectModel = Backbone.Model.extend({
    defaults:{
        name: null,
        field1: null,
        field2: null
    }
})

var AspectCollection = Backbone.Collection.extend({
    model: AspectModel
})

var EntityModel = Backbone.Model.extend({

    defaults:{
        name: null,
        aspects: null,
        children: null
    },

    relations: [
            {
                type: Backbone.Many,
                key: 'aspects',
                relatedModel: AspectModel,
                collectionType: AspectCollection
            },
            {
                type: Backbone.Many,
                key: 'children',
                relatedModel: core.Backbone.Self
            }
        ]
})

This could be deserialized to Java classes that look something like:

public class Entity {
    public String name;
    public List<Aspect> aspects;
    public List<Entity> children

    public Entity(){}   
}

public class Aspect {
    public String name;
    public String field1;
    public String field2;
    public Aspect() {}
}

I'm simplifying a lot here for the sake of clarity

[tarelli]

@mlolson for entity/aspect description have a look at http://docs.geppetto.org/en/latest/simtutorial.html

[gidili]

@mlolson that sounds like a slick way of doing it. I remember @jrmartin also looked into backbone before but we didn't end up using it as we just wanted an elegant way to handle callbacks at the time.

[tarelli]

@gidili we are using backbone for the widgets already https://github.com/openworm/org.geppetto.frontend/blob/master/src/main/webapp/js/widgets/Widget.js

[gidili]

@tarelli oh cool - I hadn't even noticed :)

[mlolson]

@gidili I'm a fan of backbone because it allows you to do some cool event driven stuff. For example, you can attach listeners to trigger callback functions on "change" or "set" events.

[gidili]

@mlolson sounds close to what we need here --> #112 also would be handy to propagate refresh actions to appropriate listeners every time the state tree changes on the client.