Microsoft's announcements at its developers' conference this week have completed a journey for its Azure technology. Previously seen - and marketed as a platform as a service technology - the introduction of Server Application Virtualisation, which allows users to run Windows Server instances as part of the Azure platform and the Windows Azure Virtual Machine Role has changed the game and for the first time has introduced Infrastructure-as-a-service into the equation.

Much of the debate on the cloud has centred on the differences between all its manifestations: Infrastucture-as-a-service, Platform-as-a-service, software-as-a-service, security-as-a-service or indeed, what HP calls everything-as-a-service. In fact, it's long been expected that some of these different offerings would move closer together and while we can see the difference between the likes of the Amazon and Google services and Azure; Microsoft has clearly moved closer to the Amazon model and is looking to a world where cloud mirrors the modern data centre much more.

But there are limitations as to how far this will go. While Microsoft now supports Windows Server in Azure, there's little sign of support for other software.: you're going to wait in vain for Linux, for example.

Microsoft has made plenty of noises in the past about the importance of cloud computing and the departure of Ray Ozzie doesn't seem to have slowed down their ambition. And while it may sound like Microsoft is blurring the distinction between IaaS and PaaS, Microsoft Server and Tools president Bob Muglia still insists that the company is a PaaS player. "Platform-as-a-service recognises that failure will happen. Failure will happen certainly within the hardware. It's designed to keep the application running through failure. When something fails it's no big deal - another instance is just spun up" he said at PDC, before announcing a further range of modifications to Azure.
>It's going to be an interesting battle over the next year or so to see whether Microsoft has got this right. The company knows that it's going to have a delicate balancing act between maintaining its on-premise business and developing its cloud offerings. There's an awful lot at stake right now.

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