Microsoft to 'open source' its Outlook PST files

Open Outlook formats helps Microsoft meet its promise to the European Commission.

Microsoft officially announced that it would be opening its Outlook's PST file format by publishing documentation. Each time in the past that Microsoft offered to publish technical specifications, the company was responding to a bullwhip wielded by the European Commission. Is this time different? Not at all.

On Monday, Microsoft promised that the published documentation of .PST " will allow developers to read, create, and interoperate with the data in .pst files in server and client scenarios using the programming language and platform of their choice, said Paul Lorimer, group manager of Microsoft Office Interoperability in a blog post. Lorimer was vague as to when the promised documentation would be available however he did say that once published, it .PST would be available as open source.

UPDATED 10/27/09: Microsoft confirmed that Microsoft only plans on publishing the documentation for Office 2010 files.

On Monday Lorimer wrote:

"When it is complete, it will be released under our Open Specification Promise, which will allow anyone to implement the .pst file format on any platform and in any tool, without concerns about patents, and without the need to contact Microsoft in any way."

Microsoft has previously published the .PST file by opening the Outlook Object Model, which was an interface that allowed .Net applications to tap into Outlook 2007. But, notes the folks at Betanews, the Object Model assumed that Outlook 2007 was running.

The EC had months ago forced Microsoft into promising to open more of its core applications. In July, the EC noted, as part of its press release regarding Web browser competition:

"In July 2009, Microsoft also made proposals in relation to disclosures of interoperability information that would improve interoperability between third party products and several Microsoft products, including Windows, Windows Server, Office, Exchange, and SharePoint (see MEMO/09/352 ). Microsoft is publishing improved proposals on its website. The Commission welcomes this initiative. Even though it remains informal vis-à-vis the Commission, Microsoft’s proposal, which is in the form of a public undertaking, includes warranties that Microsoft offers to third parties and that can be privately enforced."

The timing of today's news makes me wonder if we will be hearing from the EC, perhaps on Tuesday, announcing that another wrist slap of Microsoft. Every other time Microsoft opened one of its more precious file formats, the next day the EC announced fines or investigations. But then again, maybe such public admonitions are no longer necessary. Maybe Microsoft knows that it had better make announcements every quarter -- even ones with vague timing like this one -- that it is opening more of its file formats. Next up, we should be hearing about SharePoint.

UPDATED 10/30/09: A spokesperson for Microsoft contacted me to take issue with how I presented this news, telling me I got it wrong. Here are her gripes:

  • "The subhead of the article - “Open Outlook formats helps Microsoft meet its promise to the European Commission” – is untrue.  To be clear, Microsoft has never discussed .PST with the EU. The work was done on their own – as a response to feedback from partners and customers – and was not because of a mandate. 

  • "The article also notes that “once published, it .PST would be available as open source.”  This is not true. The PST documentation will be provided in such a way that open source implementers can use the documentation – under the Open Specification Promise - to access the PST, but there is no plan to release it as open source.  Just wanted to clarify the difference there."

I can see how these viewpoints represent the way Microsoft sees it -- or wants others to see it. But I respectfully disagree that my analysis was wrong. Let me explain. The EC's press release in July clearly mentions “Exchange” as one of the products that Microsoft promised to document/open … so in my opinion it is splitting hairs to say that Microsoft decided on its own to open Outlook under the Open Specification Promise (which is the “promise” that came about as result of EU pressure).

As for whether the way Microsoft releases .PST files is “open source” or not … my thought is, if it looks like a horse, smells like a horse, acts like a horse, it’s a horse, which is why I quoted Lorimer when he said the documentation would be available for anyone to implement it without concerns of patents or need to contact Microsoft. While it’s true that this does not mean that its available under a specific open source license … if the source is openly available to see and use without license fees to the creator, that’s my idea of a horse.

I’m sure there are many who would feel that my rationale is offbase, that what Microsoft is doing with .PST doesn’t qualify as open source (and don't worry, they’ll contact me to tell me so). Such opinions are just as “right” as mine. That said, I think anything Microsoft does to makes its source code open is good for its customers, which is ultimately good for the company.

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