Category: Technology

More CSS in JavaScript, this time with React

In September I mentioned a talk at Strange Loop 2014 where the speaker described a technique for writing CSS in the form of JavaScript which then executes to produce the actual CSS. This avoids a server-side build process, it knows more about the browser while operating, it avoids a HTTP round-trip, and has various other advantages. However, the tooling the speaker was talking about was closed source inside of the conference speaker’s product.

Today I encountered a presentation online by a React expert at Facebook, who uses React’s mapping from JavaScript to HTML+CSS, to accomplish many of the same things and more – using tools openly available.

If anyone knows of a audio or video recording of the talk, I would appreciate a link very much.

My own experiments with programmatic CSS also react, but behind ClojureScript, so I’m writing Clojure code which turns into CSS. It is not as mature as what is described in the slides above, but it adds yet another layer of abstraction in the form of a higher-level language.

Task Based User Interfaces

Here at Oasis Digital, the bulk of our work is on complex business data systems. These projects sometimes involve a so-called task-based user interface. Briefly, this is an interface where the operations available to the user are presented in terms of the problem domain, rather than in terms of editing data. Other names for this idea include “task-focused user interface” and “inductive user interface”.

Origins

I was unable to determine the specific research/practice origins of task-based UI, but it is most commonly seen as arriving from three main directions. First, the inductive user interface guidelines published by Microsoft around 2001 lay out a detailed description and motivation. Second, the domain driven design (DDD) and command query responsibility separation (CQRS) communities often described task-based UI as suitable for use in front of the system built with those principles. Third, simply looking at mass-market software there are numerous examples.

CRUD

Task-based UI is the opposite of CRUD UI, a convenient foil. Many software systems have numerous features which are readily described as CRUD: create, read, update, delete. Some developers describe their work as primarily creating CRUD systems, with either pride or disdain. When analyzing a proposed feature or proposed software project, we sometimes evaluate the extent to which the project is “just CRUD” versus behavioral functionality. Brought to the user interface, CRUD typically means screen after screen in which users can make an entity of some kind, find an existing one, update one, or remove one. In other words, a minimal veneer over basic database operations.

Simple CRUD user interfaces have the advantage that they are generally easy to create, and amenable to common tooling. Many development environments offer wizards or libraries to ease such creation, and this dates back to at least early 1990s, and probably much farther than that.

Therefore, CRUD has a lot of appeal when first creating a new application. Unfortunately, a system built primarily around CRUD tends to make behavior beyond minor validation unduly difficult to implement. If you find yourself squeezing business logic into an “on change” or “on click” event handler somewhere, you are probably experiencing this difficulty. As systems grow in complexity this bad fit can consume vast amounts of time and money.

There is a way out, and that is a task-based user interface, one which presents the user with options and actions which fit the problem domain of the software, rather than those which appear to manipulate data in trivial ways.

Change of Address Example

A common example to explain task-based UI is a change of address operation in a system which has subscribers, members, or some other class of people to whom things might be mailed etc. The CRUD approach to change of address is simple: the user searches for the appropriate user record, views that record, moves the cursor to the address fields, types over those values, and clicks “save”. Very convenient, very easy to program.

Unfortunately, down the line if there is nontrivial behavior in the system, it can be extremely difficult to determine what such an edit means. Was the address corrected because it had been mis-entered in the past? Was the ZIP Code changed because the post office changed the ZIP code assigned to that physical location? Or does this edit represent the person moving to a different place of residence? If the latter, how might that affect them in terms of the problem domain?

To avoid this, a task-based user interface would not only present address fields which can be edited. Rather, the user would see information about a person (including their address) then have options (buttons or whatever else is suitable in the visual UI guidelines at hand) with names like “correct mis-entered address”, “subscriber moved to another residence”, etc. Such explicit actions make it possible to capture the underlying domain-level meaning, rather than just edits to data fields. A downstream system receiving this information could then respond appropriately.

Choose Your Words Wisely

Task-based user interface is therefore to a considerable extent about words: the words which describe actions the user can take. If a system merely uses a task-based user interface on top of a CRUD-centric back-end implementation, then the words can at least be chosen well in the user interface. If the system uses a domain driven approach internally, then some of the well-chosen words in the user interface may become part of the ubiquitous language used throughout the implementation.

I encourage developers to consider a task-based approach even if the underlying system is not particularly domain driven.

Add, Edit, Delete, +, –

Speaking of words, having built numerous user interfaces, I very often still “default” to wire framing with button labels like “add” and “delete”. Such things are fine for an early initial wireframe, but task-based design principles suggest reconsidering whether a more specific set of operations is suitable.

An example came up at work today with a list of employees, and the initial proposal was a “delete” button next to each one. But one does not merely delete an employee: at even the most heartless of companies there will be quite a lot more process involved in removing an employee from a list of employees. A system which manages the employees then, should probably have some sort of process flow around that removal, and it should use words other than “delete”.

A Final Quip

If the user wanted Excel, they would use Excel. If they are using an application which is instead specific to a problem domain, then it should have features, both internally and at the user interface level, relevant to that problem domain.

Links

http://en.wikipedia.org/wiki/Task-focused_interface
http://msdn.microsoft.com/en-us/library/ms997506.aspx
http://codebetter.com/iancooper/2011/07/15/why-crud-might-be-what-they-want-but-may-not-be-what-they-need/
https://cqrs.wordpress.com/documents/task-based-ui/
http://stackoverflow.com/questions/12255874/what-is-an-example-of-a-task-based-ui
http://codebetter.com/gregyoung/2010/02/16/cqrs-task-based-uis-event-sourcing-agh/

FlightJS, an event-centric JavaScript library/framework

Are events your favorite part of AngularJS?
Look at FlightJS instead.

Angular’s Event System

At Oasis Digital, we use AngularJS for most of our client-side “SPA” web development. AngularJS is well suited for data and form centric enterprise web applications we most often work on; I’ll write more about why we chose AngularJS another time.

As we teach our Angular Boot Camp class, we spend time on the AngularJS event system. For those who haven’t looked at it, AngularJS’s event system operates at a higher, more abstract level then DOM events – AngularJS events propagate up-and-down AngularJS scopes rather than up-and-down the DOM directly. We typically recommend it only for narrow cases where some bit of information should be transmitted and responded to broadly across the application; it avoids the computational cost of numerous watches.

In both these classes and our development work, we sometimes meet developers who are very excited by the AngularJS event system, and endeavor to create an event-based application with it. We must then unfortunately give the following disappointing advice:

If you are looking to build a mostly event-based system, AngularJS is probably not the right tool for you. There are a lot of merits to events, but the event-centric approach is not the AngularJS way. If you’re going to build primarily with events, you are wasting much of the AngularJS ecosystem, which is primarily about scopes, data binding, directives to enhance HTML with technology and domain specific add-ons, and so on.

DOM Events Find a Home

But that is not to say events are bad. Events are great. Don’t lose hope. There is a home for you: Twitter’s FlightJS.

FlightJS is 100% event centric and DOM-centric; it embraces the browser DOM with minimal abstraction. FlightJS is tiny – according to its website “Flight is only ~5K minified and gzipped. It’s built upon jQuery.” FlightJS fits in well with JavaScript ecosystem; because it adds so many fewer features than one of the big frameworks, there is little to get in your way of using it with any other common tool. Based on a quick look at its mailing list and GitHub repo, is getting a small amount of traction, though perhaps much less so than the big frameworks.

Here at Oasis Digital, we are not switching to FlightJS, and we don’t force an event centric approach on our AngularJS work, in which we aim to stay squarely in the mainstream of AngularJS practice. But if something comes up where events are the right solution, we know where to look, and now you do too.

 

HTML to Hiccup Conversion

Recently I wrote about alternative HTML syntaxes and in-language HTML DSLs like Hiccup. Those posts were about the broad issues. This one is about a boring and practical one.

Hardly any project consists entirely of fresh newly-written HTML. Most projects have snippets of HTML brought in from a (hopefully properly licensed) framework or template. For example, sometimes to start an application page I’ll use some HTML from a Bootstrap example page.

Such examples are written in ordinary HTML, not an alternative syntax or DSL, so I need a way to quickly and mechanically convert HTML to (in this example) Hiccup. A couple of years ago I wondered this, did some research, and put a few answers in the Hiccup repo wiki. It (still unchanged as of this writing) lists these tools capable of converting HTML to Hiccup:

Of those three, I found hiccup-bridge and this workflow quite easy to use:

  1. Add [hiccup-bridge “1.0.0-SNAPSHOT”] to project.clj
  2. Save example HTML snippets or pages in files
  3. lein repl
  4. (require ‘[hiccup-bridge.core :as hicv])
  5. (require ‘clojure.pprint)
  6. (clojure.pprint/pprint (hicv/html->hiccup (slurp “html_source/plain.html”)))
  7. Copy output or portions thereof to source code
  8. Repeat for additional files

Of course this could easily be wrapped in to a one-liner command line operation; but for maximum convenience someone should make an online tool for this conversion, analogous to Html2Jade. Maybe I’ll make such a thing, if no-one else does first.

Separation of Concerns != Separate Languages

A while back I wrote about the merits (and problems) of alternative HTML syntax such as Jade, HAML, etc. Another form of alternative syntax for HTML is an “internal DSL” in a programming language. There are various examples out there, including Domo for JavaScript and Hiccup for Clojure/CLJS.

Screen Shot 2014-10-03 at 10.16.20 PMScreen Shot 2014-10-03 at 10.17.29 PM

Hiccup syntax (which is to say, Clojure syntax) is of particular interest to me. Clojure spans server and web client code very well, and Hiccup data structures can be fed directly to Reagent for a concise and efficient dynamic web application based on React under the hood. Observe this snippet:

(defn lister [items]
  [:ul
   (for [item items]
     ^{:key item} [:li "Item " item])])

…in which ordinary Clojure “for” is used for iteration in a web page. I am experimenting with this tool stack – who knows what might emerge.

Why would anyone want to do this?

The reasons I have heard most often are:

  • Many projects are excessively polyglot without good reason. Even an “all JavaScript” project with a Node server typically has JavaScript, HTML, CSS, perhaps Sass, and various mini-languages (like CSS selectors) embedded inside.
  • Separation of Concerns does not have to mean separation of programming languages; even with separate programming languages, there are countless examples of poor separation of concerns, such as Java logic in a JSP template.
  • Your main programming already has a way to (for example) loop, yet you need a new and different way to loop at each layer.

The main reasons to stick with typical, different languages per layer/concern are more obvious:

  • Developers and non-developers probably already know how to use HTML and CSS; in particular, non-developer designers may have little interest in anything but HTML.
  • There are millions examples online for HTML and CSS.
  • Everyone else uses HTML and CSS as they are, let’s just do the same thing.

So again, why would anyone do this? The answer is as with other choices to use unusual technology – a chance to beat the averages and produce more value per time spent.