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RE: Interest in standardizing Batch methods?

From: Daniel Brotsky <dbrotsky@adobe.com>
Date: Wed, 9 Jan 2002 08:15:30 -0800
Message-Id: <p05101010b86192418770@[153.32.158.166]>
To: "Lisa Dusseault" <lisa@xythos.com>
Cc: "Greg Stein" <gstein@lyra.org>, "Jim Whitehead" <ejw@cse.ucsc.edu>, "WebDAV" <w3c-dist-auth@w3.org>
At 9:29 PM -0800 1/8/02, Lisa Dusseault wrote:
>... A batch MOVE operation can do those in one
>transaction, so that the whole request fails if not all can be moved.  This
>becomes rather more important if the client is actually using an API
>(MSDAIPP??) that offers large-scope operations, yet how can it guarantee
>that operation will work or won't work if it can only send it piecemeal to
>the server?

I'm really glad you brought this up, Lisa.  It's basically the 
"transactional server needs transaction boundaries" issue, and it 
points out a common and important difficulty inherent in broad 
standards: if you specify a transactional protocol then it doesn't 
allow for simple implementations (which can be quite useful), but if 
you don't specify a transactional protocol then people who implement 
transactional client/server pairs need extensions that provide 
missing features.

In general, I think you need a layered protocol model (such as what's 
happening with DAV and delta-V) to satisfy both camps. 
Unfortunately, the base DAV protocol wasn't really well-designed to 
have transactions layered on top of it, because even single 
operations (such as DELETE) aren't required to have transactional 
semantics.

I would certainly be interested in working on a transactional 
DAV-based protocol (delta-t ? :^), although I agree with Lisa it 
ranks behind a number of other issues in base DAV (and ACL and 
delta-V) itself.  I wouldn't, however, be interested in adding 
batch-oriented calls to base DAV: while I completely understand 
Microsoft's use of extensions like this, and while Adobe does the 
same kind of thing (e.g., specialized headers to handle the 
difference between "unlock and advance taskflow" versus "unlock but 
don't affect taskflow"), adding batch operations to WebDAV feels much 
more like an appropriate application-specific patch than the basis 
for a good general-purpose transactional extension.

     dan
-- 
Daniel Brotsky, Adobe Systems
tel 408-536-4150, pager 877-704-4062
2-way pager email: <mailto:page-dbrotsky@adobe.com>
Received on Wednesday, 9 January 2002 12:57:55 GMT

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