Two exciting projects I've been recently working on at Mediamatic Lab are two highly
connected sites around the Jewish Community in the Netherlands during
World War Ⅱ. The first is one of the oldest sites we have made, the
Digital Monument.
This site contains verified information on all of the Dutch jews that
have died during WWⅡ along with their households, documented posessions
and known documents and pictures. It is maintained by a team of editors
of the Jewish Historical
Museum.
The second is a brand new community site, to
complement the Monument by allowing anyone to add new information,
pictures and stories on people at the Monument.
The Monument is very impressive, as I learned back at the first
BarCamp
Amsterdam, hosted by Mediamatic. You will know what I mean if
you spend a little as five minutes paging through the site. Today,
however, I want to talk about the technology behind both sites.
Data Model Changes
The data in the Monument is highly semantic in nature. People are
part of households, as head-of-family, spouse, son or daughter. Or
some other relation. Households have a location and lists of
possessions. Tied to all of these are supporting documents and
pictures. In anyMeta,
all of these are modeled as things with
edges between them with a certain predicate. A
typical household would be modelled like this:
For the community site, however, we wanted to have more direct
relationships between people: parent-child relations, sibling
relations, partner relations and a more generic (extended) family
relationship. As the community also has most things of the monument
imported, this meant a change in the data model and a subsequent
conversion in the monument.
In anyMeta, (almost) everything is a thing. As such, the
predicate on an edge between two things is also represented by a
thing. This has traditionally been named role.
Like all things in an anyMeta site have a resource
URI, the resource URI of a role is the predicate's URI.
We try to use existing (RDF) vocabularies as much as possible for
this.
For relationships between people, we've used the
knowsOf and friendOf properties
from RELATIONSHIP,
used in FOAF. So this was the first place to look for the desired new
predicates. However, this vocabulary does not have a property for
expressing a generic extended family relationship. Fortunately,
XFN has the
kin relationship type, along with
child, parent,
spouse and sibling.
Richard Cyganiak described how to express XFN relations in
RDF, so we used that to base our predicates on.
Like RELATIONSHIP, most of the XFN properties are subproperties
of the foaf:knows property, and have some
hierarchy themselves, too. In anyMeta, we didn't have the concept of
subproperties, yet, so we added a new role for expressing subproperty
relationships between roles, and introduced the concept of
implicit edges. These are edges with a
superpredicate of the explicit edge that is being created. For
example, the xfn:child property is a subproperty
of foaf:knows. Whenever an edge between two people
gets created with the child role, another implicit one with the knows
role is added, too.
After conversion and with the implicit edges present, the new
data model of the example above looks like this:
The blue arrows are the new, derived edges. A spouse edge is made
between those people that respectively have a head-of-family and
partner relation to the same household (this can be assumed to be
correct for this dataset). For person that have a son or daugther
edge to a household, a child edge is made from the head-of-family and
partner persons (if any) in that household to this person. We haven't
(yet) added derived sibling edges, as this relation depends on the
parents of both persons, too.
You can also see gray, dashed edges. These are the implicit edges
that follow from the property hierarchy. Another thing to notice, is
that the biographies are gone. We put the texts in there directly on
the persons and households, instead.
Besides the regular pages of all people, households and other
things, you can also use our semantic browser to look at the
relationships between things. For example, Mozes and his
family can be browsed from here.
