Today at the OSCON open source software convention, the Apache Software Foundation (ASF) got an unexpected new sponsor: Microsoft. The Redmond software giant, which will contribute $100,000 annually to the ASF, joins Google and Yahoo as a platinum sponsor of Apache development.

The ASF is a nonprofit group that exerts loose organizational guidance role over a sprawling ecosystem of autonomously managed software projects, including the Apache web server and a host of libraries, frameworks, toolkits, and programs. The culture of the ASF is built upon what they call the "Apache Way," a philosophy of consensus-based collaborative stewardship and volunteerism.

I spoke with Apache Software Foundation (ASF) president Justin Erenkrantz, who views Microsoft's sponsorship of Apache as a step forward for interoperability. He believes that this move is based on a legitimate desire by Microsoft to foster collaborative development of Apache technologies that implement Microsoft standards. In particular, he points out an ASF project called Apache POI which offers native Java libraries for reading and writing Microsoft Office file formats.

I asked him if this could possibly be the beginning of a broader initiative by Microsoft to increase Apache compatibility with .NET web development technologies, but he says it's still too early to guess Microsoft's future plans for Apache participation. He says that the Apache community, like the license it uses, tends to be pragmatic and naturally receptive to corporate involvement. He doesn't anticipate a confrontational response from the developers working on individual Apache projects because they are already accustomed to positive collaboration with the numerous companies that participate in Apache development. The response of the broader open source software community, however, is harder to predict.

Microsoft's interest in funding Apache projects is likely driven by consumer demand for interoperability. A growing number of companies are deploying Apache-based technologies on top of Windows servers. Microsoft's understanding of enterprise open source adoption is evolving and the company has slowly been taking steps to foster its own community of Windows-based open source software developers.

Erenkrantz told me that Microsoft has been moving in this direction for quite some time. The company recently invited several Apache contributors to visit its Redmond headquarters for informal interoperability talks. Microsoft's recognition of the role that open source software will play in enterprise infrastructure comes directly from the top, he says, and isn't just confined to rogue elements within the company.

Microsoft's history of antagonism to and mixed messages on open source software will likely lead some critics to see the move as a potential trap. Prudence and scrutiny are certainly justifiable wherever Microsoft is involved, but it seems unlikely that there is any possible mischief in this arrangement; the governance model of the ASF just doesn't leave room for abuse.

It isn't clear yet what level of involvement Microsoft will choose to have, but any level of involvement represents strong validation of the Apache ecosystem and the open source software model. This will hopefully be the start of a mutually beneficial arrangement for Microsoft and the Apache community.

Update: Microsoft's Sam Ramji comments on the new partnership with the ASF and some other open source announcements in a blog entry