It’s been a big month for Microsoft and open source. The company joined the Eclipse project and open-sourced some plug-in code. It announced SQL Server will be made available for Linux (presumably for the benefit of Azure). It now has a range of Android apps available. The news keeps flowing in, and plenty of people are impressed by the efforts.

Microsoft wants to be seen as a community member on both Linux and Android, plus in a wide range of developer technologies. An enormous charm offensive is in progress. A Microsoft employee is president of the Apache Software Foundation. Microsoft is buying open source companies like Revolution and Xamarin, and it's partnering with Red Hat. Microsoft is donating pocket change to all sorts of communities and conferences. The company's activities seeking open source community recognition and approval are too numerous to list here.

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But while this has been going on, you're not hearing about another part of Microsoft. Simultaneous with the Eclipse and SQL Server announcements, Microsoft announced it had successfully extracted patent licenses out of Wistron of Taiwan for its use of Android and out of Rakuten of Japan for use of Linux and Android. Though there’s been something of a lull in patent aggression lately, it has a long history and generates a significant revenue stream.

Yes, that’s right: With one face, Microsoft wants us to forgive and forget the “cancer” comments, the dirty tricks, and the standards fixing. Even as the body of SCO lays slightly warm following the Redmond-financed fight against Linux, Microsoft wants us to overlook more than a decade of hostility and accept it as a full-status community member because it showed up with code, cash, and compliments. But with the other face, Microsoft wants members of the Android and Linux communities where it claims membership to pay up crates of cash for patent licenses or face destructive litigation.

Which community member is next, and for which project Microsoft claims to love?

Open source depends for its success on having guarantees in advance: that users and developers may freely use, improve, and share the software involved. It’s antithetical to open source for those engaged in it to seek permission (and payment) from users or developers on top of the rights delivered through an OSI-approved copyright license. That’s why so many companies involved in open source -- nearly 2,000 -- have forsworn patent aggression by joining the Open Invention Network (OIN). All have exchanged the patent aggression for open collaboration.

Doing so isn’t an obstacle to using patents for self-defense -- that’s clearly stated in OIN’s license agreement. It’s not even an obstacle to patent aggression outside the world of open source. IBM, a founder and cornerstone of OIN, has a chain of patent kills to its name and currently has its fangs embedded in Groupon as its next intended victim.

But joining OIN is a clear signal to the open source community at large that you count yourself as a participant and not as a parasite. That’s why my repeated response to Microsoft news on Twitter remains the same: “But have they joined OIN yet?”

It’s very well for Microsoft to proclaim its love of open source, but it can’t have it both ways. Should it truly decide to become one of us, collaborating in an environment where everyone has permission to use, improve, and share code for any purpose, Microsoft would be welcome. Or it can be a hostile predator, stalking users and developers of Linux and Android and shaking them down for patent licenses. In that role, everything it does will be met with suspicion.

Which will it be? It’s time for Microsoft to put up or shut up. Join OIN, or admit that you can’t be trusted in the open source community you now claim to love.