% Linguistic and Architectural Requirements for Personalized Digital Libraries
% Joachim W.~Schmidt,  Gerald Schr\"oder, Claudia Nieder\'ee, Florian Matthes} 
% Submitted: 7.9.96 to Peter Bunemann for Publication in 'Digital Libraries'
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\journalname{Journal of Digital Libraries}
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\title{Linguistic and Architectural Requirements for\newline Personalized Digital
Libraries} 

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\author{Joachim W.~Schmidt\and Gerald Schr\"oder\and Claudia Nieder\'ee 
\and Florian Matthes} 

%\authorrunning{Joachim W. Schmidt et al.}

\institute{Technische Universit\"at Hamburg-Harburg, Arbeitsbereich Softwaresysteme, 
Harburger Schlo{\ss}stra{\ss}e 20, D-21079 Hamburg, Germany}

%\thanks{}

\mail{j.w.schmidt@tu-harburg.d400.de}

\date{Received \today; accepted \today}

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\begin{abstract}
\small
Our vision of digital libraries is influenced by our experience 
with systems for persistent and networked object management and with polymorphic programming languages for their implementation. When viewed from this perspective, the
essence of digital libraries can be captured by the following three
essentials:

\begin{itemize} 

\item the content of a digital library is represented by two kinds of information entities: on the basic level there are
\e{information tokens} as supplied by information providers on the net; value is added to such tokens by individually
constructing \e{information artifacts} over them with the goal of information consumer satisfaction; 

\item the services required for artifact construction and use -- on the information level as well as on the level of
the software artifacts required for these processes -- rely heavily on powerful \e{binding environments} for
multi-medial, persistent and networked information;
 
\item the processes of artifact construction and use are in themselves valuable sources of information about artifacts;
for the exploitation of such process information, digital libraries employ advanced \e{tracing environments}.

\end{itemize}

We derive linguistic and architectural requirements for digital
libraries from these above essentials. On the language level we
concentrate on generalized requirements for the \e{typing}, \e{binding} and \e{scoping} of library entities and
services. On the system level we discuss architectural requirements in
terms of \e{orthogonal persistence}, \e{open extensibility},
\e{platform independence}, \e{mobility} and \e{reflection}.

We present Tycoon \cite{MaSc92a,MSS95}, a polymorphic, higher-order
language and its system, and demonstrate its potential for digital
libraries. We evaluate Tycoon's rich conceptual basis (\e{data},
\e{functions} and \e{threads}), library-based extensibility, powerful
binding mechanisms, its orthogonal persistence and its capability of
network-wide data, code and thread migration.

We conclude by referring to an interdisciplinary digital library
project in Art History Research based on icons, texts and data. Here,
Tycoon effectively supports the process of individually customizing and
scaling library services thus generalizing the notion of a query
language into that of a persistent personal reference library.

\end{abstract}


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\begin{acknowledgement}
This research was supported by Esprit Projects ISC-CAN-080 and 22552-PASTEL. 
\end{acknowledgement}

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