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Re: Statements/Reified statements

From: Jonas Liljegren <jonas@rit.se>
Date: 23 Nov 2000 17:27:02 +0100
To: schwaenzl <Roland.Schwaenzl@mathematik.Uni-Osnabrueck.DE>
Cc: champin@bat710.univ-lyon1.fr, melnik@db.stanford.edu, www-rdf-interest@w3c.org, Wraf development <rdf@uxn.nu>
Message-ID: <874s0yfycp.fsf@astral.paranormal.se>
schwaenzl <Roland.Schwaenzl@mathematik.Uni-Osnabrueck.DE> writes:

> Bag <-type- A -rdf_1-> B           =        Bag <-type- A -rdf_1-> C
>               -rdf_2-> C                                  -rdf_2-> B
> It makes sense to ask whether some resource is a member of a bag. Does it make sense 
> to ask a resource, to be the "second" member of a bag? 

Let's say you are in a highly dynamic enviroment.

You are iterating through a hugh list of resources returned to you as
the answer to some twisted query.

What happens if the answer changes while you are iterating?

Maby best to just add new results at the bottom of the list.  If _245
dissapears, it could be made to point at nothing.

Think about search results returned one page at the time.  It would be
a waste of time to insert all the objects in the container before they
are needed.  Maby we just look at the first page?  This means that the
bag may not even be populated before it's actually accessed.  (I have
thought about this for implementation in the Wraf.)

I think of two basic ways to access the contents of a container:

 1. With a next() method for the container object

 2. Random access to the specific resource.  In the common case, we
    will access the first (and only) resource in the container.

We could minimize confusion by pregenerate the whole bag and make it
private for the requestor.  For large questions, it would be better to
not create the bag but rather provide the method for iteration.  For
common questions it could be an idea to save the query result and
change it then necessary.  It's in this latest case there strange
things can happen if the content change while we are reading form it.

/ Jonas Liljegren

The Wraf project http://www.uxn.nu/wraf/
Sponsored by http://www.rit.se/
Received on Thursday, 23 November 2000 11:26:01 UTC

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