Subject: FW: Partial Property Data Retrieval???

From: "Jim Whitehead" <[email-masked]>
Date: Thu, 4 Sep 2003 16:58:49 -0700

Accidentally caught by the spam filter. I've added Frank's email to the
accept2 list.

- Jim
-----Original Message-----
From: Frank Judge [mailto:[email-masked]]
Sent: Thursday, September 04, 2003 4:37 PM
To: [email-masked]
Subject: [Moderator Action] Partial Property Data Retrieval???

Hi,

I've read over the specifications and want to know if I'm missing something
or if you considered a capability.  For properties in a schema that have
large amounts of data, does WebDAV specify a means to retrieve only portions
of that data?  For example, if you have a document object that has only a
text property containing all the document data, you may only want the first
100K of a 10 megabyte document.  For email the POP and IMAP protocols allow
subsets of the message data to be retrieved ( POP TOP command for
instance ).  Have you thought of allowing retrieval of only a subset of
property data, and if you have could you point me to the reference that
shows how?

Thanks,

Frank Judge
Palm Inc.
[email-masked]

---

From: Chris Knight <[email-masked]>
Date: Fri, 05 Sep 2003 11:02:17 -0700

Frank Judge wrote:

>I've read over the specifications and want to know if I'm missing
>something or if you considered a capability.  For properties in a schema
>that have large amounts of data, does WebDAV specify a means to retrieve
>only portions of that data?  For example, if you have a document object
>that has only a text property containing all the document data, you may
>only want the first 100K of a 10 megabyte document.  For email the POP
>and IMAP protocols allow subsets of the message data to be retrieved (
>POP TOP command for instance ).  Have you thought of allowing retrieval
>of only a subset of property data, and if you have could you point me to
>the reference that shows how?
>  
>

Alas, WebDAV does not allow for retrieval of part of a property. It 
would be very interesting and useful for large structured properties, as 
you've said. Probably would have to support 
XPath...http://www.w3c.org/TR/xpath

---

From: Chris Knight <[email-masked]>
Date: Fri, 05 Sep 2003 11:28:58 -0700

Jim Whitehead wrote:

>For example, if you have a document object
>only want the first 100K of a 10 megabyte document.
>
In retrospect, this is a different question...HTTP/1.1 currently 
supports the "Range" header for GET requests that would satisfy your 
requirement to download parts of document data.

See *ftp://ftp.isi.edu/in-notes/rfc2616.txt*