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Re: Is APPEND really needed ?

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 08 Aug 2006 10:27:36 +0200
Message-ID: <44D84AF8.20507@gmx.de>
To: Jim Whitehead <ejw@soe.ucsc.edu>
CC: edgar@edgarschwarz.de, w3c-dist-auth@w3.org

Jim Whitehead schrieb:
> One rationale for a separate APPEND are filesystem-like clients (WebDAV 
> file system drivers, for example) that want to be able to map filesystem 
> append capabilities onto WebDAV. This provides a simple method that 
> allows them to do this. Append is one scenario where WebDAV filesystems 
> perform very poorly as compared to alternative network filesystems.

I agree with that, but I think the problem is not just append, but also 
seeking and truncating. APPEND only fixes one of these cases, where a 
PATCH format can fix all of them.

> Authoring clients are the primary target for PATCH, as they have 
> knowledge about fine-grain changes to resources. AFAIK, WebDAV file 
> system drivers don't typically have enough information to send an update 
> and use PATCH for sub-file changes.

Sorry? A file system driver usually has to map a set of write 
operations, such as seek, write, truncate, so we just need a patch 
format that can transport this information, such as 
the-one-published-as-a-note-by-the-W3C (I recommend not to look at it 
unless it becomes clear that there isn't IETF-unfriendly IPR attached to 

> Con:
> * method is more complex: implementors need to implement mandatory 
> append, text, and binary patch formats

Well, I guess we would have two (file op, text patch) mandatory patch 
formats rather than one. I don't see how this is worse than having two 
methods instead of one.

> * no longer possible to implement just append capability on its own

Aha, you want to make those independent? In this case just let all patch 
formats be optional.

Even if I would buy the reasoning for a second method, I'd still make it 
more powerful so that it can do a sequence of seek/write/truncate as 
well (in which case it wouldn't be called "APPEND" :-)).

Best regards, Julian
Received on Tuesday, 8 August 2006 08:27:49 UTC

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