XML Paper Specification, or XPS, is a new XML-based format for creating formatted documents. Seen as a direct competitor to Adobe's Portable Document Format (PDF), it is one of the more controversial features in Windows Vista. Because it touches so much of the Windows infrastructure, it is expected to affect all users in one way or another.
XPS shares many of the same features as PDF. Both are positioned, or being positioned, as the de-facto format for documents that need page based layouts. Both can be created by having applications print to a special printer driver. Both offer free readers.
The key difference is that Adobe makes its money from PDF editors, while Microsoft is practically begging developers to build their own editors right into their applications. So if XPS takes off, Adobe stands to lose.
Ken Fisher of Ars Technica reports that Adobe did file a complaint with the European Union over XPS. Rather than ordering it removed from Vista, the EU has obtains assurances from Microsoft that XPS will be handed over to a standards body. The end result is that XPS is in a stronger position to become the new cross-platform standard for documents.
This isn't the first time Adobe went toe-to-toe with Microsoft over open file formats. Earlier this year Adobe forced Microsoft to pull PDF support from Office 2007 under the threat of a lawsuit.
A stand-alone viewer and the XPS print writer is included in Vista. Windows XP users can download these in the Microsoft XPS Essentials Pack. XPS is also supported by Office 2007.
For application developers, Microsoft has included the ability to read and write XPS documents in Windows Presentation Foundation. Being an XML-based standard, WPF isn't strictly required and developers are free to build their own libraries.
XPS also changes the game for hardware manufacturers. As of Windows Server 2003, kernel mode print drivers were disabled by default. With Vista, they are not available at all. In exchange, users get support for XPS-based printer drivers. These drivers promise improved rendering and spooling capabilities. Inline filters allow for advanced color control, an essential feature for graphic artists. Asynchronous notifications offer the ability to inform the user not only how many pages have been printed so far, but also how far along it has gone through the rendering and filtering stages.
Microsoft is also targeting IT professionals with XPS. One of the touted advantages is that it is a safe format. Unlike Word documents and PDF files, which can contain macros and JavaScript respectively, XPS files are fixed and do not support any embedded code. The inability to make documents that can literally change their own content makes this a preferable archive format for industries where regulation and compliance is a way of life.
Finally there is the HD Photo Specification. This is a "new file format for continuous tone still images that surpasses the limitations of existing image formats." Specifications for both XPS and HD Photo Specification can be found on the Windows Hardware Developer Central.