Rome Wasn't Digitized in a Day - Council on Library and Information ...

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services, or “build<strong>in</strong>g blocks of specialized functionality,” <strong>in</strong>clud<strong>in</strong>g functionalities such as
tokenization, lemmatization, and collation that are “wrapped <strong>in</strong>to <strong>in</strong>dividual services to be re-used by
other services or plugged <strong>in</strong>to an application environment”; (3) the TextGrid middleware; and (4)
stable archives (Aschenbrenner et al. 2009). They have also developed a semantic service registry for
TextGrid. Ziel<strong>in</strong>ski et al. have offered a concise summary of their approach:
The TextGrid <strong>in</strong>frastructure is a multilayered system created with the motivation to hide the
complex grid <strong>in</strong>frastructure … from the scholars and to make it possible to <strong>in</strong>tegrate external
services with TextGrid tools. Basically <strong>in</strong> this service oriented architecture (SOA), there are
three layers: the user <strong>in</strong>terface, a services layer with tools for textual analysis and text
process<strong>in</strong>g, and the TextGrid middleware, which itself <strong>in</strong>cludes multiple layers (Ziel<strong>in</strong>ksi et al.
2009).
Nonetheless, the TextGrid project faced a variety of data <strong>in</strong>teroperability challenges <strong>in</strong> terms of us<strong>in</strong>g
the TEI as its basic form of markup, s<strong>in</strong>ce partner projects used the TEI at vary<strong>in</strong>g levels of
sophistication. While they did not want to sacrifice the depth of semantic encod<strong>in</strong>g the TEI offered,
they needed to def<strong>in</strong>e a m<strong>in</strong>imum “abstraction level” necessary to promote larger <strong>in</strong>teroperability of
computational processes <strong>in</strong> TextGrid (Blanke et al. 2008). As a solution, TextGrid developed a “core”
encod<strong>in</strong>g approach:
… which follows a simple pr<strong>in</strong>ciple: one can always go from a higher semantic degree to a
lower semantic degree; and <strong>in</strong> possession of a suitable transformation script, this mapp<strong>in</strong>g can
be done automatically. TextGrid encourages all its participat<strong>in</strong>g projects to describe their data
<strong>in</strong> an XML-based markup that is suitable for their specific research questions. At the same time
projects can register a mapp<strong>in</strong>g from their specific, semantically deep data to the respective
TextGrid-wide core encod<strong>in</strong>g that is a reasonably expressive TEI-subset (Blanke et al. 2008)
TextGrid’s solution thus attempts to respect the sophisticated encod<strong>in</strong>g of local practices while
ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g a basic level of <strong>in</strong>teroperability. This illustrates the difficulties of support<strong>in</strong>g cross-corpora
search<strong>in</strong>g even with<strong>in</strong> one project. All content that is created with the help of TextGridLab or comes
from external resources is saved unchanged to the TextGrid repository. Metadata are extracted and
normalized before be<strong>in</strong>g stored <strong>in</strong> central metadata storage, and a full-text <strong>in</strong>dex is extracted from the
raw data repository and updated with all changes (Ludwig and Küster 2008).
The TextGridLab tool (an Eclipse-based GUI) is <strong>in</strong>tended to help users create TEI resources that can
live with<strong>in</strong> the data grid. Although TEI documents form a large part of the resources <strong>in</strong> TextGrid, it can
handle heterogeneous data formats (pla<strong>in</strong> text, TEI/XML, images). TextGrid also provides a number of
basic services (tokenizers, lemmatizers, sort<strong>in</strong>g tools, stream<strong>in</strong>g editors, collation tools) that can be
used aga<strong>in</strong>st its objects while also lett<strong>in</strong>g users create their own services with<strong>in</strong> a Web services
framework:
Web Service frameworks are available for many programm<strong>in</strong>g languages—so if a person or
<strong>in</strong>stitution wishes to make his/her text process<strong>in</strong>g tool available to the TextGrid community and
the workflow eng<strong>in</strong>e, the first step is to implement a Web Service wrapper for the tool and
deploy it on a public server (or one of TextGrid’s). The next steps are to apply for registration
<strong>in</strong> the TextGrid service registry and to provide a client plug-<strong>in</strong> for the Eclipse GUI so that the
tool is accessible for humans (GUI) and mach<strong>in</strong>es (service registry) alike (Ziel<strong>in</strong>ski et al. 2009).