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Developers say Microsoft has "betrayed" them by changing strategy on the Silverlight web technology.

When first announced Silverlight was portrayed as a rival to Flash and key to getting Microsoft software running on many different devices.

Now Microsoft is slowing Silverlight development and turning its attention to web standards such as HTML5.

Silverlight will remain as a way to get apps running on Windows phone 7.

The strategy shift emerged as a result of an interview that Bob Muglia, Microsoft's head of servers and tools division, gave at the company's Professional Developers Conference.

In that interview, he said Silverlight was still "core" to Microsoft but the company was looking to other technologies such as HTML to get its software running on devices people use to get at online sites and services.

saying that exploding use of e-readers, tablets and different sorts of smartphones now made it "practically impossible" to get something like Silverlight running on all those devices.

Like Adobe's Flash, Silverlight acted as a wrapper that, once installed on a machine, allowed that device to run code written for it. Many sites used it as a way to present rich video and multimedia to visitors.

Silverlight also made it easier for developers to hook into the many back office systems Microsoft produces to help enrich the services that could be put online.

Mr Muglia said the shift on strategy was not a "negative statement" but a recognition that the industry had changed.

The furore kicked off by Mr Muglia's comments also led Microsoft boss Steve Ballmer to underscore the software giant's commitment to Silverlight .

Despite this, many of the comments on Mr Muglia's blogpost took the software giant to task for the change.

Developers described themselves as "betrayed", "disappointed" and "demoralised" by the decision.

Others said they felt they had wasted the time they had invested in learning to use Silverlight and others said they would now consider changing to rival technologies.

Many pushed for more clarification on the future of Silverlight and when the next version of the software will be available.

Microsoft has only said it would talk about a release date for Silverlight 5 "in the coming months".