Monday, December 12, 2016

Why MVC will die out like the incunable and the dinosaur

There is hardly a web-framework around these days that doesn't base itself around model-view-controller, a programming paradigm as old as the hills of software engineering. It was invented at Xerox PARC in the '70s. Back then, when dinosaurs roamed those digital hills, MVC was a useful abstraction that simplified the development of desktop applications. With the invention of the Web, MVC was quickly ported to many frameworks that advocated doing everything on the server to overcome the inconsistency in Web-browsers' implementations of Javascript and CSS. So Java frameworks like Spring, and PHP frameworks like Zend adopted the MVC idea and made it core. But what is MVC exactly? "Model" is clear enough: that's the database and all interactions with it. "View" is clearly the GUI, which in Web applications is HTML/CSS/Javascript. "Controller", though, is less clear. It's the glue that arbitrates interactions between the model and the view. Without it the view would have to directly manipulate the model, or vice versa, which would be bad. But the basic problem with MVC is that it compels the developer to conflate the database code with the GUI development. That is, the model and the view are written in the same language and then the GUI result is spat out to the client who consumes it. All this is very Web 1.0 by design.

Web 2.0 and what it changed

Web 2.0 changed all that by turning the pages themselves into the web application. Without the GUI being part of the server-side code, web-applications are simply services that supply and consume data. And that data is, increasingly, being sent and received in JSON format. What need of the controller now? The funny thing is, the MVC paradigm was revised to cope with Web 2.0 as well. A sort of "web-incunable" – an incunable being a 15th century book that aped the design of manuscript books in type. In the same way, MVC is a kind of desktop application being aped in web applications – trying to do all work in a single place, when the separation of the model and the view is already implied by the Web 2.0 application model.

15th Century print incunable (manuscript lookalike)

Doing everything in one place using whatever framework we choose compels us to handle GUI-related stuff (e.g. composing HTML code and ensuring that it calls the correct Javascript functions etc) on the server. And that means that the framework will be very complex, and all those beans, taglibs, JSPs, ASPs and PHPs only exist to cope with all that functionality. And when the framework gets updated, the poor programmer has to dance the tune of the framework developer. "Oh, by the way Sir, in version 2.1.1 you have to change all your calls to the database because we changed the API. Sorry.". Or worse still: "Due to a fall in demand the product Framework X has been discontinued. Users should migrate their code to Framework Y. Sorry for any inconvenience this may cause." And the poor programmer again is compelled to do a lot of work because he/she joined all their code at the hip to that once popular framework.

Doing (almost) everything on the client

Doing almost everything on the client reduces the complex server part to a mundane: "here is data, store it" or "Get me some data about X". And the language is HTTP/JSON. The GUI code can GET and POST all it needs directly without reference to a "Controller". A web-page is increasingly a template where data is filled in asynchronously as it becomes available. We can now deal with the "business logic" where it is logically decided: in the GUI, and now your web-application will become as simple as a piece of cake: simple to develop, simple to maintain. Inconsistency in the way that browsers handle Javascript and/or CSS is not quite a thing of the past but is at a sufficiently low level to make this possible. The natural separation between model and view is now enshrined in the physical separation of server and client. And MVC will eventually go the way of the incunable and the dinosaurs that preceded it.

An extinct dinosaur

Won't that slow down the client?

I hear some skeptics cry: "But that will slow down the client, which is a thing we never do." In fact MVC slows down the client all the time by rebuilding the GUI on the server whenever the data changes. Even the humblest smart phone nowadays packs a whallop in processing power. The real limit is bandwidth. Once the application is downloaded to the client it runs there as long as it is needed, fetching only the necessary resources. "Oh but we can do AJAX also with MVC." True, but done properly that will no longer be MVC. If you really want a responsive interface then the code has to execute locally. So MVC is not only overly complex, but a resource hog too. You still hear the old mantra: "Your application should still run even if Javascript is turned off." But nowadays, turning off Javascript is like turning off the Web. No one is seriously going to do that.

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