What kind of issues are you going to face? What questions are going to keep coming up?

“… but how do I do postbacks?”

The loss of the postback model is going to hit a lot of web developers hard – there’s a big mindset shift to make. So how did we get here, and where are we going?

In the history of web development so far, there have basically been two major different approaches/philosophies to web UI.

1. Event-driven

Just like with native GUI apps, we imagine that when the user clicks a button, we can change the text on some label. When they change a value in a list, the “total” is updated. The fact that this stateful UI has to be transmitted over HTTP is just a technical obstacle to be overcome.

2. RESTful

Following the principles of REST and SOA, we understand that the cleanest web apps are stateless. We think in terms of requests and responses, working with HTTP rather than against it.

While RESTful apps are the fashion today, don’t forget that it’s the older technology. In 1997, the age of Perl, we had no choice. The first Event-driven platforms came later, achieving their statefulness through complicated abstraction layers (ASP.NET), fiddly scripting (AJAX), or abandoning HTML entirely (Flash).

Here’s another way of comparing the two mindsets:

Event-driven	RESTful
ASP.NET	RoR, MonoRail, ASP.NET MVC
Stateful	Stateless
Heavyweight	Lightweight
Overcomes HTTP	Embraces HTTP
Widgets	HTML
3rd-party controls	DIY
Design view	Code view
GUI	Web page
Postbacks	-
Partial page updates*	Full page updates
Web 1.0 (uncool)	Web 2.0 (cool)

##

• I know classic ASP.NET actually replaces the whole page on a postback, but *the mental model *is that it’s doing partial page updates. It just technically uses full page updates to achieve that.

Note I’m trying to keep AJAX out of this, because it’s just a way of strapping extra event-driven semantics on top of whatever other platform you’re using. I totally accept that it’s useful today, but in 3-5 years it will be gone and we won’t miss it.

So which should I use?

Another way to think about the progression of these approaches is like this:

	RESTful	Event-driven
Ineffective web technology	Perl, Plain PHP	ASP.NET
Effective web technology	RoR, MonoRail, (ASP.NET MVC?)	?

The most effective web frameworks today are undoubtedly the highly-streamlined, designed-for-HTTP, MVC derivatives. I call ASP.NET “ineffective” because anyone who’s used it for more than a few years knows that the abstraction doesn’t really work, it tends to be too heavyweight, and the “page lifecycle” is the software equivalent of cholera.

What’s the future?

The future is not Ruby on Rails. It’s not ASP.NET MVC either, though that will hopefully improve our industry for the next 2-4 years and you should probably use it.

The future is, inevitably, obviously, undoubtedly, the question mark on the table above. It has to be an event-driven architecture since that matches both the end-user and developer’s instincts about UIs. But unlike ASP.NET, it will be thick-client, not a load of leaky abstractions. It may be so well integrated into the OS that users don’t think of it as being different to their local apps.

In other words, the future is client-side. Well, it’s going to be interesting anyway.