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revision 1.97 by hemppah, Fri Feb 28 12:36:15 2003 UTC revision 1.98 by hemppah, Fri Feb 28 13:18:40 2003 UTC
# Line 1613  General security considerations \cite{si Line 1613  General security considerations \cite{si
1613  \end{longtable}  \end{longtable}
1614  \normalsize  \normalsize
1615    
1616  \begin{figure}  
 \centering  
 \includegraphics[width=14cm, height=12cm]{xanadu_model.eps}  
 \caption{Xanalogical nodel}  
 \label{fig:xanalogical_model}  
 \end{figure}  
1617    
1618  \begin{figure}  \begin{figure}
1619  \centering  \centering
# Line 1652  functionality. Line 1647  functionality.
1647  \section{Overview}  \section{Overview}
1648    
1649  Fenfire project \cite{fenfireurl} is an effort to build a distributed, hyperstructured user  Fenfire project \cite{fenfireurl} is an effort to build a distributed, hyperstructured user
1650  interface system. Fenfire is licenced under GNU L-GPL. It's main goal is to implement  interface system. Fenfire is free software and it is licenced under GNU L-GPL. Fenfire's main goal
1651  xanalogical storage model \cite{ted-xu-model}. Fenfire was formely also an implementation  is to implement xanalogical storage model \cite{ted-xu-model}. Fenfire was formely also an implementation
1652  of the ZigZag\texttrademark --structure, which was originally invented  of the ZigZag\texttrademark --structure, which was originally invented
1653  by Ted Nelson. Now, however, Fenfire uses Resource Description Framework \cite{w3rdfurl}  by Ted Nelson. Now, however, Fenfire uses Resource Description Framework \cite{w3rdfurl}
1654  for representing internal data structures and their relationships.  for representing internal data structures and their relationships.
# Line 1677  functionality. Line 1672  functionality.
1672  Xanalogical storage \cite{nelson99xanalogicalneeded} is different kind of model for  Xanalogical storage \cite{nelson99xanalogicalneeded} is different kind of model for
1673  presenting data and relationships between data. While in World Wide Web links are  presenting data and relationships between data. While in World Wide Web links are
1674  between \emph{documents}, in xanalogical model links are between individual  between \emph{documents}, in xanalogical model links are between individual
1675  \emph{characters}.  \emph{characters}. Indeed, each character in xanalogical storage model has a
1676    permanent, globally unique identifier. For instance, let's consider the following
1677    scenario: ''the character 'D' typed by Janne Kujala on 10/8/97 8:37:18''. In this
1678    example, when character 'D' is is first typed in, xanalogical storage model
1679    acquires a permanent identifier for that character and retains it when character
1680    is copied to different document. Thus, identifier distinguishes chararacter from
1681    all similar characters typed in independently\footnote{Xanalogical storage model
1682    is not limited to text. It can support arbitrary data, e.g., pixels of picture or
1683    frames of video.}. The connectivity in xanalogical storage model between data content
1684    is more substantial than in other models; a link is shown between any two data contents
1685    containing a specific \emph{fluid media unit} (e.g., a character) that the link connects.
1686    In practice, however, xanalogical storage model uses \emph{spans}, ranges of consecutive
1687    fluid media units, to handle storage operations. This is done for better performance as
1688    doing expensive operations for \emph{every} fluid media unit is not efficient.
1689    
1690    \emph{Enfilade} can be considered as a ''virtual file'' (or part of one), which is a list
1691    of fluid media contents. In xanalogical storage model, links between content are external
1692    and bidirectional. Xanadu link is an \emph{association} of two enfilades, such as an
1693    annotation to a specific part of a another document. Transclusion is an inclusion in an
1694    enfilade of contents already used in another enfilade, i.e. current fluid media is copied into
1695    different data contents. By using this mechanism, system implementing xanalogical model
1696    is able to show all data content that share same fluid media with current data content
1697    (e.g., all documents containing current document's text). Figure \ref{fig:xanalogical_model}
1698    illustrates xanalogical model.
1699    
1700    
1701  4.1. Xanalocical model (some parts from our article, modify)  \begin{figure}
1702  Xanalocical model [cite] is a simple, but rather different model for representing content.  \centering
1703  Project Xanadu [cite] has been a pioneer implementing xanalogical model. In xanalocical model  \includegraphics[width=14cm, height=12cm]{xanadu_model.eps}
1704  links are not between documents, but individual characters.  \caption{Xanalogical nodel}
1705  For instance, when a character is first typed in xanalogical, it acquires a permanent ID  \label{fig:xanalogical_model}
1706  ("the character 'D' typed by Janne Kujala on 10/8/97 8:37:18"),  \end{figure}
 which it retains when copied to a different document, distinguishing  
 it from all similar characters typed in independently.  
 A link is shown between any two documents containing the characters  
 that the link connects. Xanalogical links are external and bidirectional.  
   
 In addition to content links, xanalogical storage keeps an index of  
 transclusions: identical characters copied into different documents.  
 Through this mechanism, the system can show to the user all documents  
 that share text with the current document.  
   
     * Enfilade: a list of fluid media contents, a "virtual file" or part of one  
     * Transclusion: the inclusion in an enfilade of contents already used in another enfilade  
     * Xanadu link: an association of two enfilades, such as an annotation to a part of a document  
     * pdf files are stored in image blocks  
     * Documents can be created by listing new content or transcluding existing content in an enfilade.  
     * Annotations can be entered as new content and Xanadu-linked to a part of document.  
   
1707    
1708    
1709  \section{Storm}  \section{Storm}

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