Possible prior art for Microsoft XML patent found

An open source application could potentially invalidate a patent that Microsoft was granted for XML serialisation last week.

A ZDNet UK reader pointed out on Thursday that SXP, a library for converting C++ programming objects into XML files, was made available on Sourceforge in February 2000. Microsoft filed its patent for the conversion of programming objects into XML files in June 2001, over a year later.

Patents are granted by the patent office on condition that there is no prior art — that no-one has evidence for a similar technology that is older than the patent. If SXP does constitute prior art, it could invalidate the Microsoft patent.

Microsoft wouldn't say whether it believed the SXP library was an example of prior art, but instead pointed enquiries towards the US Patent and Trademark Office (USPTO).

"If there is prior art related to this patent, there is a process for third parties to submit that prior art to the USPTO. The public input mechanism is an important part of the USPTO’s patent review process and it is available to anyone to use," said a Microsoft spokesperson.

Microsoft was granted the patent for XML serialisation by the US patent office. A number of software developers and ZDNet UK readers have expressed anger that Microsoft was been granted this patent, claiming that it is obvious and in general use. But Microsoft defended itself, claiming that its innovations are "among the most significant across any industry".

The controversy over this patent began just days before Microsoft announced that the next version of Office will include new XML-based file formats for its Excel, PowerPoint and Word applications.

Microsoft said that companies can integrate Office documents with applications without any charge as it has granted a royalty-free licence for the XML-based file formats.

"Microsoft Office Open XML Formats are fully documented file formats with a royalty-free license. Anyone can integrate them directly into their servers, applications and business processes, without financial consideration to Microsoft," Microsoft said in a statement.

The wording of Microsoft's XML serialisation patent suggests that it could cover any application that converts between programming objects and XML files, so it is possible that Microsoft could charge a licence fee to anyone integrating XML with applications or business processes.

Microsoft said that it has not investigated potential links between the patent and the Office Open XML Formats.

"We have not analysed whether any of the claims in the XML serialisation patent are actually related to the Office XML file schema and any report that said there was a connection would be speculation," said a Microsoft spokesperson.