Sharing Knowledge: Scientific Communication - SSOAR

166 Judith Plümer
Migration from HTML META to RDF
Above we indicated the advantages that RDF has in comparison with HTML
META. The question that we want to discuss here is how the software can handle
the richer structure.
HTML META is in a mathematical sense equivalent to the SOIF format since
both store attribute/value pairs. But that precludes the use of RDF on the base of
the current harvest software. What we need is a software with the power to handle
RDF and the wisdom to integrate SOIF data that come from some gatherer
agents in the world and don’t want to update their software.
In the CARMEN (http://www.math.uos.de/projects/carmen/) project of the
federal ministry of science (Global Info program of the BMBF) tools were developed
that can be plugged together to operate MPRESS on the basis of RDF.
X-Harvest
The X-Harvest [Kokkelink, 2000] software is a modification of the Harvest-NG
(http://webharvest.sourceforge.net/ng/) software that substitutes the internal
SOIF format by RDF. That means X-Harvest is a substitute for the gatherer
component of the Harvest software which stores the summaries of the documents
in RDF format. X-Harvest is completely written in Perl. That makes addition
and modification of features easy but on the other hand it makes the installation
a real challenge: the Harvest-NG software needs the installation of 8 additional
Perl modules which require further Perl modules. X-Harvest needs additional
Perl modules which piles up to 25 Perl modules totally that have to be installed.
Therefore we decided to implement a script that takes care of the installation
procedure.
But this modular architecture solves for example the problem of character
sets because X-Harvest uses the Unicode module and hence handles Unicode
characters.
As well there are modules for the X-Harvest software that are able to solve
the heterogeneity problems that we mentioned above:
What do we do with HTML documents without any metadata and with documents
coming up in formats that are not able to carry metadata information like
PostScript? For this purpose there is a summarizer that generates metadata out
of HTML documents on probabilistic guesses and a summarizer for PostScript
documents that extracts metadata by given heuristics (http://www.math.uos.de/
projects/carmen/AP11/). The use of heuristics in this context makes complete
sense since mathematical papers are at most all of the same structure and mostly
offered in PostScript which was generated out of TeX/LaTeX. This, however, is
an aspect for which the described solution does not have to be scalable for other
disciplines.