Microsoft has placed the hypercall application program interface (API) for its Viridian virtualization server under the banner of its Open Specification Promise (OSP) (http://www.microsoft.com/interop/osp/default.mspx). But will it help company notch up more open source street cred?

The hypercall API for Viridian, which comes as part of Windows Server 2008 (http://www.microsoft.com/windowsserver2008/default.mspx), enables developers to integrate non-Windows virtualization components with Windows Server.

Under Microsoft's OSP arrangements "any individual or organisation is free to implement, commercialise and modify Microsoft’s virtualization format technology for free, now and forever". This means developers can build components under operating environments such as Linux and incorporate them with Windows Server 2008 without fear of infringing Microsoft's intellectual property.

Microsoft has been vigorously courting partners for its version of virtualization in the face of intense competition from market leader VMWare. Its two main partners - Novell and Citrix - have been quick to support the move. Novell has, of course, been working closely - and controversially - with Microsoft on virtualization. The two worked up an agreement (http://www.regdeveloper.co.uk/2007/02/13/ms_novell_swing/) to share developments in virtualization technology earlier this year.

The Viridian technology is expected to be released as Windows Server Virtualization within three months of Windows Server 2008's February 27th 2008 release. ®

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