Sherman,
as another alternative, I urge you to take a look at Explorator [1]
(there is a short movie explaining the basic idea, you can also play
with the live interface), which can do all of what you said, and more.
It provides a more general exploration paradigm, of which the example
you give below is only one of the possibilities...
Best
Daniel
[1] http://www.tecweb.inf.puc-rio.br/explorator.
Sherman Monroe wrote:
Dan,
...
As for pivoting and set-based browsing in general, it's a very novel
paridigm that requires more study, espeically user-oriented studies.
It's easy to mis-apply old methods to this new UI approach, for
example, how Parallax creates a 1-dimensional (i.e. 2-directional)
breadcrumb trail. This is borrowed from WWW browsing, where the only
directions from the "subject" (i.e. web page loaded) is back and
forward. But in a linked database, the number of directions from a
subject is equal to the number of possible types of the links from
that subject to its objects. So it's a truly n-dimensional hyperspace.
Thus, the 2D-breadcrumbs trail, while helpful, does not truly orient
user's current position in the database. Here is my attempt to
describe how navigating the linked dataspace would feel in real life,
to better bring out the point. Image a linked database as a building,
and each room contains a set of one or more resources matching a
SPARQL criteria, and along the walls of the room are portals leading
to other rooms, where each portal represents an RDF property those
resources share. Now say I'm browsing a social network database, and
I'm in DanBrickley's room, and I open and enter his *foaf:knows*
portal. Now I am in /DanBrickley >> foaf:knows/ portal. The portals in
here represent all the properties shared by all the folks Dan knows.
Where can I go? I can go back through the DanBrickley portal, or
through one of the property portals. Now here is the magic introduced
by the structured XML SPARQL query. Suppose that from here, I want to
enter the *foaf:interest* portal. In there, I see /semantic web/. Now
I kick out all the other resources in this room, so that only semantic
web remains. If I go back into the *foaf:interest* portal through
which I came, I now find this list of friends is narrowed to just
those whose interest is semantic web. The abilty to manipulate a room
and have it affect the state of all other rooms in my breadcrumbs, is
something you can't currently do with Parallax, because of it's 2D
navigational path (David or anyone, I make this statement after having
tried witht he interface myself, the browse all>> link on properties
is the cloest thing I found). Now from this room (the /friends whose
interest is semantic web/ room), I now go through the
*foaf:currentProject* portal. I have now forked my criteria (an
ability that was in Piggybank/Longwell, but missing from Parallax for
some reason). Here I find the /Umbel Project/. Because each resource
also acts like a portal (thanks to resource dereference :), I enter
the /Umbel Portal/, and now I'm in a new room inside a totally new
building containing rooms specialized around technology projects (a
building represents a SPARQL endpoint, linked database source, an RDF
graph, etc). So the portals can lead into/out of any building
imaginable. Parallax only allows for navigating inside one building,
i.e. Freebase, a second short coming.
Not to pick on Parallax at all, it's outstanding work that must
continue to be pushed and improved, so I'm just here to whet the
concepts it introduces. I have found the above visualazation of the
linked database helpful in my work with linked data browsers, most
recently razorbase. I've toyed with the notion of a 3D linked data
browser along these principles, but don't know if that could actually
be more useful than simple tables for large audiences.
