Mar 30, 2016

Open Ember Questions

#programming #frontend #ember.js

I have some open questions about Ember that I'd like to talk about.

I don't think these questions have answers, but I'd like to hear if/how people are addressing these concerns.

  1. Acceptance Testing
  2. Coupling of UI and Route Hierarchy
  3. What is a Component?

Note: It's possible that I'm highly misinformed about any/all of these subjects or that you could help me reframe the problem in a way that makes the solution obvious.

If you're reading this and it's still EmberConf, I would be very much interested in talking in person. Find me at @mehulkar on the tweeter.

Also note that none of these are deal breakers and have various solutions or workarounds. I am interested in talking about them anyway.

Acceptance Testing

How do I organize my UI development so that acceptance tests can retrieve changes from a rapidly developing API and stay relevant/useful?

Possible answers:

  1. Ember CLI Mirage is the touted solution to acceptance testing at the moment, but I don't think it allows you to consume the actual API codebase at a revision. I hear it does let you fallback to a live version of your API, so with the flip of a switch, I could run my tests against a live API, but the extra overhead to maintain a live API (in a clean state) seems...hard.

  2. Dedicated QA for end-to-end testing. This is not only expensive, but I think the existence of QA might also encourage lazy development.

  3. Improve communication/cross polination across the UI and API teams and manually keep API spec changes in sync. This is usually fine, but manual communication is slower and prone to errors. Also, this is a cultural solution and will take time to develop.

  4. Work on API and UI serially, instead of in parallel, so one project becomes well defined before the other and can dictate the constraints and requirements. This is net slower, and creates a less flexible project plan.

  5. A solution I'd like to explore is to generate UI mock endpoints with a revision of the API codebase directly, and on the fly. This will inevitably require a closer coupling between API and UI projects. Possibly even putting them in the same source control repository? (gasp!)

    This is an unpopular opinion because isolating API and UI seems to be a popular architectural pattern these days. I think, at least for the projects I've worked on, this forced decoupling has actually been a form of overengineering and doesn't have many benefits except the promise that, some day in the future, the separation of projects will be useful. I concede that I haven't worked in software long enough to have seen this use case.

Coupling of UI and Route Hierarchy

I've found that the hierarchy of my DOM is very closely tied to the hierarchy defined by my routes. This is because, by default, an {{outlet}} is rendered inside a DOM element that is rendered by the parent route.

For example, with these routes: () {
this.route("post", function () {

if I navigate to the post.detail route and want to render a set of buttons (upvote, comment, edit, etc), the easiest solution would be to put the buttons in the post.detail template. This feels natural and works out of box because these buttons will be rendered in the correct context and scope.

But what if I wanted these buttons to appear in the app header? Rendering outside the UI hierarchy defined by the route would involve some manual rendering or some wiring up of injections in weird places.

Maybe I'm missing something trivial, but if this has never happened to you

  • my app structure is either fundamentally wrong different, or
  • the various workarounds (like render in Ember.Route), are actually the right solution and I need to get over the fact that they feel wrong, or
  • there are use cases for decoupling UI hierarchy from route hierarchy.

It's possible that I'm still thinking of my application in terms of the the 1.x Route + Controller + Template mentality. It's possible that components will be arbitrarily renderable into any place in the DOM and will be the solution here.

But that brings me to my next question:

What is a Component?

I've heard of components in two different ways:

In the HTML web component kind of way, where an object encapsulates behavior and style and can be used in a variety of settings. A good example is the {{link-to}} helper. You could say that this component is domain agnostic.

The other way is a component that is a portion of the application itself. For example, the {{about-page}} component is rendered on the /about route. You could say that this type of component is very much domain driven.

To me, this overloads the concept of Ember.Component and I'm grappling to find the balance between domain agnostic and domain driven components. It seems okay to have both, but I believe that both require their own set of patterns (and maybe a different set of APIs?) A good example is that domain driven components could use a store injection to make API calls.

Another open questions about components is that, if everything should be a component, and Ember.Controller is going away, where does the orchestration of components happen? How do they liaison among each other? Entirely in routes? Service injections? Does all this liaisoning get pushed into some global Application state? Does that defeat the purpose of the neat encapsulation offered by components, in the first place?

Just some thoughts.

Find me at @mehulkar to dig deeper / tell me what I'm missing.

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