THE TYPOLOGICAL DATABASE SYSTEM

	Paola Monachesi, Alexis Dimitriadis, Anne-Marie Mineur, 
		Rob Goedemans, Manuela Pinto

We present the design and provisional architecture for the Typological
Database System (TDS), a project for the creation of a unified interface to
independently developed typological databases.

Typological databases provide descriptive information about large numbers of
languages (typically 100 or more), and are an important tool for typological
work.  Many such databases exist, and are increasingly being made available to
the general linguistic community via the internet.  However, such databases
can differ considerably in their terminology, notation, organization of their
content, and in the operation of their host database management system (DBMS).
In addition to the usual problem of resource discovery, then, their effective
utilization presents the following challenges:
 
1. Correct and effective use.  Different databases use varying terminology,
   notation, organization of the data, and search commands.  Even if these are
   documented in detail, they can be quite difficult for a new user to
   assimilate and employ properly.
 
2. Efficiency of resource utilization.  As the amount of online information
   grows, the task of searching databases one by one and collating the results
   becomes an obstacle to their efficient utilization.

The TDS aims to overcome these obstacles by presenting a single, uniform
interface to a collection of typological databases, a ``virtual database.''
The component databases remain on remote servers (although local copies could
be made for performance reasons), and are queried by the TDS during the
execution of user queries.

The system relies on detailed formal descriptions (metadata), prepared in
advance and describing in detail the structure and content of each component
database.  The metadata is used to match a user query against the capabilities
of the component databases.  The TDS will then transform the user's query into
queries suitable to the one or more databases found to contain relevant
information, submit the queries to the appropriate databases, collect their
responses, and present them to the user.

The system will make use of a uniform linguistic vocabulary, chosen so as to be
understood by, and useful to, as much of the linguistic community as possible.
Users will be able to construct queries using either the uniform vocabulary or
the terms of the individual databases.  In general the correspondences will be
only partial, and the system must ensure that the user is aware of the exact
semantics of the query being performed.  The system will also provide
traditional, forms-based query screens with predefined views of the
data.