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Users of the Wilson O/R Mapper sometimes ask for some documentation about OPath in their user forum, since the mapper supports a query language similar (or identical?) to OPath.

They cannot find the documentation on the Microsoft Longhorn website anymore because, from Microsoft's point of view, the version of OPath they ask for is deprecated. It was conceived for the now abandoned ObjectSpaces project.

Inspired by the ideas from OPath (itself being heavily inspired by XPath), I created a "derivative" language (that is now quite different), which I later decided to call OQuery. That's why I sometimes wanted to look at their documentation, so quite a while ago I recovered the docs from the Web Archive. I've cached them here because in my experience the Web Archive can be slow at times.

This may qualify as an "unauthorized reproduction" (blame the Web Archive first, MSFT!), so please, dear Wilson O/R Mapper users, when reading and using it, do observe their copyright.  =)
(But don't take their patent too seriously, because you can't actually.)

The ObjectSpaces articles that were still available might be useful when working with Wilson O/R Mapper (a design goal of which seems to be to mimic the ObjectSpaces API design). All links within these documents are broken. An incomplete list in no particular order:

Accessing Object Data Using ObjectSpaces

Note: This may well be the last and only posting in the OPath category from me---unless someone else wants to write more about the topic. Note that OPath is evolving and getting a new, quite different life in WinFS (or WinFX? Something to mix up easily), so Paul Wilson might want to consider finding a new name for the query language used in his O/R mapper to avoid confusion with technology deployed with a future release of Windows and the .NET Framework. (But not "OQuery"! :)

Update: just realized that OPF3 also uses OPath, presumably also the now deprecated ObjectSpaces variant. So if you're interested in OPath content, you may find stuff there as well (I haven't checked their documentation). Paul and Christian, get in touch, team up and rename your query languages together!  ;)

Posted on Monday, May 23, 2005 3:39 AM Querying: OPath | Back to top


Comments on this post: (Deprecated) OPath Documentation

# re: (Deprecated) OPath Documentation
Requesting Gravatar...
We are going to rename our language soon ;-) I don't know what Paul is going to do - i really never had the chance to get in contact with him.
Left by Christian Liensberger on May 27, 2005 4:28 PM

# re: (Deprecated) OPath Documentation
Requesting Gravatar...
I think MS's plans are clear as mud -- so I'm not changing anything, at least for the foreseeable future. I based my API on ObjectSpaces, but just because ObjectSpaces has been delayed (or cancelled depending on who knows what) does not make my usage of the API any different. It was a great starting point for my ORMapper, but I've always felt free to extend it when it made sense, so I've got quite a bit now that ObjectSpaces never had. I've got support for every imaginable database (unlike ObectSpaces) and I've added lots of DAL-like features too -- and now I've even got support for Generics and Nullable Types. As for OPath, I never included much of OPath -- until just this week actually since I had a user (Jeff Lanning) contribute a pretty major OPath engine based on the latest public Longhorn specs. Maybe it will never be released by MS, or it may change a lot, but for me and my users it works just fine today -- and that's what matters.
Left by Paul Wilson on May 28, 2005 1:50 PM

# re: (Deprecated) OPath Documentation
Requesting Gravatar...
> that's what matters.

Couldn't agree more on this last point... =)
Left by Phil on May 28, 2005 6:39 PM

# re: (Deprecated) OPath Documentation
Requesting Gravatar...
Paul is right. Microsoft makes it very unclear what they want and what they release in the end. They cancel 99% of what they say... The best is probably waiting.
Left by Christian Liensberger on May 29, 2005 12:07 PM

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