Subject: RE: What is DASL for?

From: "Julian Reschke" <[email-masked]>
Date: Sun, 9 Jun 2002 16:42:32 +0200

> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Alan Kent
> Sent: Thursday, May 30, 2002 12:59 AM
> To: WebDAV
> Subject: What is DASL for?
>
>
>
> This might sound like a very naive question, but I am trying to understand
> the use cases for DASL. That is, what sorts of problems are people trying
> to solve? Being an open framework to drop any sort of query you like into
> it to me does not improve interoperability in the long term.
>
> ...
>
> Hence my question of what is the goal:
>
> * To enable searching of content? (Similar goals to say google)

It's important to understand that DASL consists of

a) a framework for the HTTP SEARCH method, enabling different kinds of query
grammars, and

b) one specific (and mandatory) query grammar, specialized in searching on
WebDAV properties (it has a single function for content matching, but this
is optional).

> * To enable searching through a file system to find files that match
>   certain properties (more like "Find Files" under windows") in a
>   way that is faster than the client doing PROPFIND etc on each
>   individual file.

Definitively.

> If the latter, I would implement the query engine without using indexes,
> and just do the file system walk at the server end and check the various
> conditions to find matching resources.

Well, that's up to you. Even if a DAV:basicsearch query affects both dead
(stored) and live (computed) properties, it may be able to come up with a
better query strategy that does not require a tree walk. See for instance
Elias' paper at [1].

[1] <http://dav.cse.ucsc.edu/dasl/mod_dav_dasl.pdf>