UPDATED: By joining the Open Invention Network, Microsoft is offering its entire patent portfolio to all of the open-source patent consortium's members.

Several years ago, I said the one thing Microsoft has to do -- to convince everyone in open source that it's truly an open-source supporter -- is stop using its patents against Android vendors. Now, it's joined the Open Invention Network (OIN), an open-source patent consortium. Microsoft has essentially agreed to grant a royalty-free and unrestricted license to its entire patent portfolio to all other OIN members.

Before Microsoft joined, OIN had more than 2,650 community members and owns more than 1,300 global patents and applications. OIN is the largest patent non-aggression community in history and represents a core set of open-source intellectual-property values. Its members include Google, IBM, Red Hat, and SUSE. The OIN patent license and member cross-licenses are available royalty-free to anyone who joins the OIN community.

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Keith Bergelt, OIN's CEO, commented on Microsoft's announcement in an interview: "This is everything Microsoft has, and it covers everything related to older open-source technologies such as Android, the Linux kernel, and OpenStack; newer technologies such as LF Energy and HyperLedger, and their predecessor and successor versions."

In a conversation, Erich Andersen, Microsoft's corporate vice president and chief intellectual property (IP) counsel -- that is, Microsoft top patent person -- added: We "pledge our entire patent portfolio to the Linux system. That's not just the Linux kernel, but other packages built on it."

This is huge

How many patents does this affect? Andersen said Microsoft is bringing all 60,000 patents to OIN.

Keep in mind, as late as 2014, Microsoft made approximately $3.4 billion from its Android patents. Samsung alone paid Microsoft a billion bucks to license its Android patents. That's serious cash -- even on lucrative Microsoft's balance books.

Andersen knows the move is surprising.

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In a forthcoming blog post, Andersen wrote, "We know Microsoft's decision to join OIN may be viewed as surprising to some; it is no secret that there has been friction in the past between Microsoft and the open-source community over the issue of patents."

What changed?

In an interview in September, Scott Guthrie, Microsoft's executive vice president of the cloud and enterprise group, told me that Microsoft has undergone a "fundamental philosophical change."

The Redmond giant has been on a journey, he suggested.

"We came from a place where we were not friendly to open source," said Guthrie. But you should "look at our actions over the last five or six years . . . at the end of the day, we've shown by our actions that we're serious about open source."

With this latest move, Guthrie explained, "We want to protect open-source projects from IP lawsuits, so we're opening our patent portfolio to the OIN."

Yes, that's a top Microsoft official.

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Andersen added, "We are evolving. We're addressing what our customers and developers need. You should judge us by our actions."

This is a major sea-change.

Their actions are showing Microsoft thinks it has more to gain by opening up its patents than by charging for them. And Andersen specifically thinks this is the "next logical step for a company that is listening to customers and developers and is firmly committed to Linux and other open-source programs."

It's not April Fools' Day

This move didn't come out of nowhere.

Besides Microsoft simply contributing more to open source, Microsoft has been seeking rapprochement with its former IP enemies.

Andersen noted Microsoft pivoted about two years ago with its Azure IP Advantage plan.This gave Azure users the shield of 10,000 Microsoft patents against "baseless patent lawsuits."

Then, he said, "We joined Red Hat in bonding GPLv3's cure commitment language to open-source projects, such as Linux, covered by the GPLv2 code."

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Finally, Microsoft recently joined LOT, an anti-patent troll group.

"They aren't trying to sell you something. Microsoft really has been changing. No one's made a longer journey than Microsoft from a proprietary software company to one that lives with open source," explained Bergelt, OIN's CEO.

Why has Microsoft changed so radically?

According to Guthrie, "We recognized open source is something that every developer can benefit from. It's not nice, it's essential. It's not just code, it's community. We don't just throw code on the website. We openly publish our roadmap, and we have 20,000 Microsoft employees on GitHub. With over 2,000 open-source projects, we're the largest open-source project supporter in the world."

Andersen added, "At Microsoft, we take it as a given that developers do not want a binary choice between Windows vs. Linux, or .NET vs Java -- they want cloud platforms to support all technologies. They want to deploy technologies at the edge -- on any device -- that meet customer needs. We also learned that collaborative development through the open source process can accelerate innovation."

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So, it makes perfect sense for Microsoft to support open-source software's IP defenses. You see, Microsoft, with the major legacy exception of its Windows desktop and desktop application code, is an open-source company. I know it. It knows it.

"We see open source as central to our company mission and what our customers are trying to achieve," Andersen said.

He continued, "We believe the protection OIN offers the open-source community helps increase global contributions to and adoption of open-source technologies. We are honored to stand with OIN as an active participant in its program to protect against patent aggression in core Linux and other important open-source software technologies."

Let me remind you once again that that's Microsoft -- not, say, Canonical, Red Hat, or SUSE -- talking.

Indeed, Guthrie, Andersen, and Bergelt all said they hope this Microsoft move will help spur other companies that may be reluctant to back up their open-source code and services with their patents and to join the OIN.

Specifically, Bergelt said, "Microsoft's participation in OIN adds to our strong community, which through its breadth and depth has reduced patent risk in core technologies, and unequivocally signals for all companies who are using OSS but have yet to join OIN that the litmus test for authentic behavior in the OSS community includes OIN participation."

If Microsoft can join the OIN, you can too

So, what if your company has already signed a Microsoft patent agreement covering Android, Linux, or other open-source software? Well, it depends, according to Andersen, on the exact contract. I'll add, although I'm not a lawyer, I think if you were an OIN member, you'd be in a much better position to work out a new, better deal with Microsoft.

How do you do that? By agreeing with OIN's community practice of patent non-aggression in core open-source technologies by cross-licensing your Linux System patents to one another on a royalty-free basis.

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As time has gone on, the definition of "Linux System" has grown wider and wider. OIN patents are similarly licensed royalty free to any organization that agrees not to assert its patents against the Linux System. You can sign the OIN license online. But, before you do that, you should have a long talk with your IP attorneys.

Microsoft took years of internal change and deep consideration to make this fundamental change in both its business model and how it develops it software. In the end, open-source has won, and Microsoft is now a fully fledged open-source company. If they can do it, you can do it.

So, it seems, a leopard can change its spots. A lion and a lamb can lie together. And Microsoft can become an open-source company.

UPDATE: Microsoft clarified that it has licensed its entire patent portfolio to OIN licensees covering the Linux System. Yes, Microsoft has 90,000 total patents and the OIN covers only 60,000. But, that's 90,000 total patent includes those that are pending. Patents that have not been issued cannot be asserted and basically do not exist yet from a legal perspective. Microsoft has licensed all the patents it has in hand. As those other patents are approved, Microsoft will license those as well. That is how the OIN license works.

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