Microsoft has raised the ire of the open source community with its Windows Marketplace licence by specifically refusing to allow software covered under an open licence to be distributed.
The licence, which anyone wishing to distribute Windows, Windows Phone, or Xbox applications through the company's copy of Apple's App Store is required to agree to, is the usual torrent of legalese - but hides a nasty surprise for those who support open source ideals.
Jan Wildeboer, open source evangelist and Red Hat employee, was one of the first to spot the restrictions in Microsoft's licence this week. "One thing is extremely obvious," Wildeboer claims in a post to his personal blog. "Microsoft wants to keep its platform clear of Free Software. Period."
As evidence, Wildeboer points to Article 5 of the Application Requirements section of the Microsoft Application Provider Agreement, which states: "The Application must not include software, documentation, or other materials that, in whole or in part, are governed by or subject to an Excluded License, or that would otherwise cause the Application to be subject to the terms of an Excluded License."
The reference to 'Excluded License' refers to an earlier section which explicitly names the GNU General Public License version 3 and its Lesser derivative - two of the most common open source licences around - along with 'any equivalents.'
Effectively, the agreement requires that products shipped through the Windows Marketplace contain no open source code at all. Considering that Microsoft uses open source libraries in its own products, and has even contributed code to open source projects in the past, it's a poor showing.
The licence doesn't just stop the release of open source programmes on the Windows Marketplace, however: taken at face value, it would also prevent closed-source apps from including open source libraries - a major blow for developers.
"This, coming from the company that publicly claims to be a friend of open source," argues Wildeboer, "should make app developers think again if this mobile platform is the platform of choice."
The full Microsoft Application Provider Agreement can be downloaded directly from the Microsoft Developer Network, if you want to check Wildeboer's interpretation.