Poor old Silverlight. Once upon a time, the application framework was one of the keys to writing rich internet applications and it was the darling of a strong development community.

But it’s been a tough 12 months-or-so for Silverlight. First, HTML5 started to look good – really good. Big providers have been queuing up to back the next generation web framework, knowing HTML5 offers key features that could help break an over-reliance on a series of web-browser plug-ins.

Further pain mid-year came when Apple CEO Steve Jobs laid into rival plug-in Adobe Flash, attacking the non-standardised nature of the framework and removing the capability for Flash to work on Apple’s leading devices such as the iPad and iPhone. Plug-ins, it seemed, were no longer the flavour of the month.

But there was still Microsoft, of course – they wouldn’t abandon their own framework. Not abandon, no – but mixed messages from Redmond towards the back-end of 2010 really didn’t help the cause of Silverlight.

First, Internet Explorer general manager Dean Hachamovitch suggested that the future of the web was HTML5. Then a few weeks later, Microsoft’s director of product management for developer platforms Brad Becker said the Silverlight framework actually extended the web by enabling scenarios that HTML does not cover.

So, what are these scenarios? Well, they’re actually pretty limited. Bob Muglia, the Microsoft president in charge of the company’s server and tools business, recently said Silverlight is the provider’s development platform for Windows Phone.

Anything else, or is that it? Muglia stressed that Silverlight will also be important in specific areas, such as media. But when it comes to the big stuff – the cross-media development – then he believes that HTML5 offers the only true solution for everything.

That must be pretty tough for the legions of devoted Silverlight developers. And that rough feeling is only like to grow, as Silverlight increasingly becomes a niche platform for niche applications.

That type of specificity is simply a non-starter. The future of consumer and business interaction is the mobile. Businesses have to find ways to write once and deploy multiple times, rather than having to develop across several platforms for a broad range of operating systems and devices.

Plug-ins have a bad effect on the high quality web browsing experience. Users have to run applications before they can see content. In the worst – and increasingly large number – of cases, the plug-in might not even be compatible with the browser or device.

For individuals, the pain of plug-ins will be removed as HTML5 becomes the standard for web development. For Silverlight and its associated plug-in counterparts, the future looks grim.