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Re: Advanced Collection Requirements

From: Judith Slein <slein@wrc.xerox.com>
Date: Mon, 20 Apr 1998 07:40:28 PDT
Message-Id: <>
To: "Jukka-Pekka Numminen" <Jukka-Pekka.Numminen@poyry.fi>
Cc: slein@wrc.xerox.com, www-webdav-dasl@w3.org

I have combined your two notes and am forwarding them to the DASL mailing
list.  It seems to me that your scenario is more likely to be satisfied by
DASL than by WebDAV collections.  Would it be sufficient to have something
like an SQL order-by clause? The current DASL protocol specification does
provide this with the DAV:sortby element.  


At 11:38 PM 4/15/98 PDT, Jukka-Pekka Numminen wrote:
>I have tried to follow the WebDAV discussion because the results would be
very useful for executing industrial plant projects distributed among many
parties. If I have not completely misunderstood your work, the concept of
collections could be streched to cover an area of interest to industial
plant projects namely dynamic hierarchic collection. I hope that you taking
away the possibility to have multiple orderings of a collection does not
kill my scenario.
>The scenario (or an example):
>Engineering documents of an industrial plant can be ordered into
hierarchic collections in many ways. 
>To give you an example of two possibilities:
>Physical plant structure: plant -> department -> process -> equipment
>Document type structure: drawing -> electrical -> loop diagram -> department
>The first structure is the one a process or maintenence oriented person
uses and the second one is the one a design engineer uses. The user of the
system should be able to give the order (any order) of metadata elements
that form the hierarchy dynamically.
>There are tens (even hundreds) of thousands of documents in an industrial
plant project. To effectively navigate the mass a dynamic hierachy based on
the metadata would be very useful. In a sense this is an ordered collection
and the same collection has several ordering schemes. In addition to the
collection members it would be very important to get just the browsing tree
from the server (one could ask just for the tree that is the dynamic
hierarchy without any members)
>I hope that if this is not a part of the definition, the definition does
not prohibit (hopefully it supports) the creation of a system that works
like this.
>best regards
>Jukka-Pekka Numminen
>Jaakko Pöyry Group
One thing bothered me in the DASL working group documentation (DASL
Scenarios slides presented by Saveen Reddy 1st of April). On the Simple
Navigation slide the collections were mentioned with the possibilities to:
- list the sub-collections of a collection
- find the hierarchy of a collection (tree-view).
Is this collection used in the same sense as the collection in WebDAV. If
the collections within this navigation scheme could be dynamic (based on
for example properties), it would solve my problem? The main problem in my
scenario is to get the tree-view for browsing without extensive search
requests to the server or without predefined hierarchies. The tree-view
should be based on actual property values.

An example:

There are properties A, B and C and they have values:

     A   B   C
R1  X   Y   3
R2  X   Y   2
R3  Z   Y   3
R4  X   P   3
R5  Z   P   3
R6  X   P   2
R7  X   Y   3

for each resource Rx

The possible trees are:
1. when order is ABC
 | | |
 | | 3
 | Y-2
 |   |
 |   3

2. when order is BAC
 | | |
 | | 3
 | Z-3
   | |
   | 3

and so on. Normally you would have to first query all values of A then all
values of B where A is X or Z and so on to get the tree (could be expensive
and client specific). If the collection could be dynamic any browser with
the simple navigation tree-view capability could present the view to the
user (if the server was able to produce the hierarchy).
Sorry for a story this long and thank you for your patience.

Jukka-Pekka Numminen

Name:			Judith A. Slein
E-Mail:		slein@wrc.xerox.com
Internal Phone:  	8*222-5169
Fax:			(716) 422-2938
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Web Site:    http://www.nde.wrc.xerox.com/users/Slein/slein.htm
Received on Monday, 20 April 1998 10:34:52 UTC

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