Will Monday, 5 April 2004, be celebrated as the day Microsoft began turning into an open source company?

At first sight, the Windows Installer XML (WiX) toolset released then is just the latest piece of software distributed under Microsoft's Shared Source Initiative. This is the company's increasingly complex attempt to steal some of open source's thunder by offering classes of users degrees of access to the underlying code - mostly to look at, but in certain circumstances to touch, too.

Microsoft's nervousness about letting others see its source can be judged by the plethora of different licensing schemes now available. It is also reflected in the low- key description of the "WiX Shared Source Licensing Program". It is only when you follow the link to the SourceForge page where the project is hosted that you discover that WiX is being released under a licence that is fully approved by the Open Source Initiative. In other words, WiX is Microsoft's first open source code.

The background to this historic moment is sketched by the software's principal author, Rob Mensching. That he does so in a blog is hardly surprising these days; that he is one of more than 150 fellow Microsoft employees who not only create blogs but are allowed to share them with the world is rather more amazing.

Another of those blogs gives an insight into why Microsoft is opening up. It relates the company's new-found interest in blogging to concerns about "software quality" and the "customer connection." These are precisely the areas where free software excels, thanks to the tight links between coders and users that lie at the heart of the open source development model - and that people at Microsoft are trying to replicate through its official Shared Source Initiative as well as more informal approaches like blogs and Wikis, the latter mostly part of the interesting Channel 9 project.

The same blog contains a hint as to why the WiX posting may prove so momentous. The entry in question shows a rather drab Web page: Microsoft's first. Interestingly, it was not run on home-grown server software - because none existed - but used code that came from the European Microsoft Windows Academic Consortium (EMWAC), at the University of Edinburgh. As the official history of microsoft.com makes clear, initially there was little interest within the company for Internet technologies.

Even Bill Gates failed to get it at first, though that had changed by the time of his famous Pearl Harbour Day speech in December 1995, in which he vowed to put the Internet at the heart of everything Microsoft did. And just as the EMWAC server, modest as it was, would mark the starting point for that massive corporate transformation, so may WiX turn out to be the first, almost imperceptible move in Microsoft's re-invention of itself in the light of open source.

Those who doubt that a company so wedded to proprietary software could ever make such a huge shift may like to consider an intriguing fact about WiX. The licence that Microsoft has chosen for its first foray into open source, the Common Public Licence, was drawn up by IBM. As IBM's FAQ explains, the Common Public Licence was based on an earlier version called the IBM Public Licence. This is essentially the same as a 1998 licence used for a small program called Jikes, a Java compiler.

Few today have heard of Jikes, but it deserves more fame, since it was the first open source software that IBM ever released. The success of that and later moves led the company to adopt free software for an increasingly wide range of its products, to the point where IBM can probably be regarded today as the biggest and most important open source player. If IBM, the archetypal corporate behemoth, can make such an improbable change in just six years, how much more quickly might the far nimbler Microsoft effect the same transition?

Glyn Moody welcomes your comments.