Microsoft for the first time has complied with a European court ruling that it must document its Windows workgroup protocols, allowing other developers to implement them correctly and without fear of retaliation.

"This is what they were supposed to do in 2004," said Jeremy Allison, lead developer of the Samba open source project, a beneficiary of the information that will become available about the protocols. At the end of 2004, a Luxembourg-based court of the European Union issued a ruling that Microsoft must share information about the protocols that ran Windows Server, Active Directory, Windows user authentication, and other workgroup-related activities.

The agreement weakens Microsoft's stance that Linux and other open source code violates its patents. As part of the agreement, it will have to disclose patents that it believes cover its workgroup protocols and open source developers will have a chance to document how their code doesn't infringe the patents. If in doubt, open source developers may now rewrite code so that it gets around the claimed coverage, said Allison.

The Software Freedom Law Center, directed by Eben Moglen, negotiated the agreement with Microsoft and set up a nonprofit Protocol Freedom Information Foundation to receive the documentation. The foundation paid Microsoft a one-time fee of 10,000 Euros, or about $15,000 U.S. dollars, for the agreeing to the pact.

That amount is far less than what Microsoft might be expected to collect in royalties from users if it succeeded in imposing patent claims on Samba, Linux, or other open source code. Microsoft issued a statement saying: "We are pleased that the [foundation] has chosen to take a Work Group Server Protocol Program trade secret and copyright license from Microsoft."

The director of Microsoft's open source labs, Sam Ramji, was in the process of writing a blog on the agreement, said a Microsoft spokesman.

With the protocol documentation, Samba developers will also be able to implement the set of Windows protocols correctly rather than guessing at them by studying their effects out on the network, Allison said.

To many observers, Samba's ongoing ability to translate Windows files between Linux and Windows servers had made it a possible target for a Microsoft patent infringement challenge.

Samba is freely available code that allows a Unix or Linux server to exchange files with Windows servers. Microsoft provided technical information to Samba developers in the early 1990s as the project got underway, but as Linux started being used in the data center, Samba allowed it to become a file and print server or communications server for Windows users and to talk to Active Directory. One of Linux' early uses was as a low-cost file and print server for groups of Windows users. By 1996, Microsoft started to withhold protocol information from the open source project.

"We got too good. We became a competitor," Allison said.

The Microsoft pact was negotiated by Andrew Tridgell, the original developer of Samba. Allison was a co-developer with Tridgell and leads the ongoing Samba development team from his post at Google.

"We are very pleased to be able to get access to the technical information necessary," Tridgell said in a statement announcing the pact.

The documentation doesn't become public once it's turned over to the Protocol Freedom Information Foundation. The deal was negotiated and payment made on behalf of Samba only. But a precedent has been set with the terms of the agreement allowing Samba implementations of the protocols to go out under the General Public License, a provision that's been a sticking point in the past.

Indeed, the U.S. Department of Justice reached an agreement with Microsoft to document and license its protocols to third-party developers prior to the European Union court ruling. But it left the details of the implementation up to Microsoft. As a result, Microsoft imposed a fee on each sale of a product implementing its protocols, refused to agree to any distribution in GPL code, and set terms that restricted use of the protocols only to those proprietary companies that wished to compete head to head with Microsoft. The number of takers was limited, said Allison.