
felix@3244: \section{Configuration of the Datacage}
felix@3244: 
felix@3244: \subsection{Tasks and Recommendation types of the datacage}
felix@3244: 
felix@3244: The datacage serves two purposes.
felix@3244: It handles automatic 'recommendations', which are instructions
felix@3244: sent by the client to add newly created artifacts to the collection.
felix@3244: From a user perspective, these artifacts mainly represent curves or data
felix@3244: points in the resulting diagrams.
felix@3244: The second task is to let the user add already existing artifacts (i.e.
felix@3244: previous calculations) or new artifacts with access to related data.
felix@3244: 
felix@3244: Irrelevant of the type of elements (recommendations or user picked data) the
felix@3244: datacage can iterate over possible artifacts by accessing its own database.
felix@3244: Thus, to create a list of matching entries, database queries are used.
felix@3244: 
felix@3244: \subsection{Structure of the datacage configuration file meta-data.conf}
felix@3244: 
felix@3244: The datacages behaviour is defined in the file conf/meta-data.xml .
felix@3244: 
felix@3244: In meta-data.xml, database queries are defined as \verb!<dc:statement>! elements,
felix@3244: for example
felix@3244: \begin{lstlisting}
felix@3244:                 <dc:statement>
felix@3244:                   SELECT id          AS prot_id,
felix@3244:                          description AS prot_description
felix@3244:                   FROM wsts WHERE kind = 1 AND river_id = ${river_id}
felix@3244:                 </dc:statement>
felix@3244: \end{lstlisting}
felix@3244: 
felix@3244: As can be seen from the example, the datacage configuration file can maintain
felix@3244: its own stack of variables (\${river\_id} in above example).
felix@3244: 
felix@3244: The database query will usually deliver one or many results, over which is
felix@3244: iterated using the \verb!<dc:elements>! elements.
felix@3244: 
felix@3244: Information from this results can be used for two goals.
felix@3244: It can be taken as output, in which
felix@3244: case the client will either request the creation of these artifacts (considering
felix@3244: recommendations), or shown by the client in a the 'datacage widget',
felix@3244: the graphical representation of data which can be added in the current
felix@3244: context.  The later is seen when the user clicks on the Datacage button in
felix@3244: a diagram.
felix@3244: Or information can be used to feed a second (or third...) database query.
felix@3244: Following above example:
felix@3244: 
felix@3244: \begin{lstlisting}
felix@3244:                 <dc:statement>
felix@3244:                   SELECT id          AS prot_id,
felix@3244:                          description AS prot_description
felix@3244:                   FROM wsts WHERE kind = 1 AND river_id = ${river_id}
felix@3244:                 </dc:statement>
felix@3244:                 <dc:elements>
felix@3244:                   <additional>
felix@3244:                     <dc:attribute name="name" value="${prot_description}"/>
felix@3244:                     <dc:context>
felix@3244:                       <dc:statement>
felix@3244:                         SELECT id       AS prot_column_id,
felix@3244:                                name     AS prot_column_name,
felix@3244:                                position AS prot_rel_pos
felix@3244:                         FROM wst_columns WHERE wst_id = ${prot_id}
felix@3244:                         ORDER by position
felix@3244:                       </dc:statement>
felix@3244:                       <!-- ... -->
felix@3244: \end{lstlisting}
felix@3244: 
felix@3244: In both cases, an \verb!<dc:elements>! element makes database queries available.
felix@3244: Also
felix@3244: note how the variables are defined in the first query and reused in the second
felix@3244: query (\$\{prot\_it\}).
felix@3244: 
felix@3244: Any alement not prefixed with "dc" represents a (sub-) node in the resulting
felix@3244: tree.  The client will display these nodes and maybe subnodes in the datacage
felix@3244: widget - \verb!<additional>! in above example.  The elements name is translated by
felix@3244: the client.
felix@3244: 
felix@3244: While iterating the final results, \verb!<dc:attributes>! have to be specified
felix@3244: to define how the artifact is to be created.
felix@3244: 
felix@3244: \begin{lstlisting}
felix@3244:                       <dc:elements>
felix@3244:                         <column>
felix@3244:                           <dc:attribute name="name" value="${prot_column_name}"/>
felix@3244:                           <dc:attribute name="ids" value="additionals-wstv-${prot_rel_pos}-${prot_id}"/>
felix@3244:                           <dc:attribute name="factory" value="staticwkms"/>
felix@3244:                         </column>
felix@3244:                       </dc:elements>
felix@3244: \end{lstlisting}
felix@3244: 
felix@3244: The "name" attribute is what is to be displayed in the client, the "ids" are given
felix@3244: to the server and pass important information about the chosen data.
felix@3244: The "factory" is chosen according to the type of data displayed.
felix@3244: 
felix@3244: So far, three other elements have not yet been mentioned: \verb!<dc:comment>!,
felix@3244: \verb!<dc:if>! and the \verb!<dc:when><dc:otherwise>! structure.
felix@3244: \verb!<dc:comment>! is an element to allow comments.  Choose these over standard
felix@3244: \verb=<!-- -->= xml comments, because they are not transferred to the client.
felix@3244: \verb!<dc:if>! and \verb!<dc:when>! allow control (rather: definition) flow within
felix@3244: the configuration and work in analogy to the XSL-elements \verb!<xsl:if>!
felix@3244: and \verb!<xsl:when>!.
felix@3244: 
felix@3244: When dealing with the behaviour specification of the datacage, multiple
felix@3244: interpretations for the term "context" are possible.
felix@3244: A \verb!<dc:context>! element essentially means a database binding.  Thus each
felix@3244: query (\verb!<dc:statement>!) needs to be nested in its own context.
felix@3244: Furthermore, two types of databases with own bindings exist:
felix@3244: The "system" (default for \verb!<dc:context>!, \verb!<dc:context connection="system">!)
felix@3244: context allows queries related to the backend database with existing
felix@3244: data (e.g. measurements).
felix@3244: The "user" context (\verb!<dc:context connection="user">!) allows queries against
felix@3244: the database which stores information about already existing artifacts and
felix@3244: calculations.
felix@3244: 
felix@3244: Another connotation for the term "context" is the situation from which
felix@3244: the datacage is queried.  The standard case is a from the datacage widget.
felix@3244: When the user opens the datacage from the graphical client, this is done
felix@3244: from one of possible multiple diagrams.
felix@3244: When the datacage is queried, it gets as an argument the "out" of
felix@3244: the current artifact.  The out corresponds to the diagram type.
felix@3244: 
felix@3244: For example the inner block of
felix@3244: 
felix@3244: \begin{lstlisting}
felix@3244:           <dc:if test="dc:contains($artifact-outs, 'longitudinal_section')">
felix@3244:               <longitudinal_section>
felix@3244:                 <dc:call-macro name="annotations"/>
felix@3244:               </longitudinal_section>
felix@3244:           </dc:if>
felix@3244: \end{lstlisting}
felix@3244: 
felix@3244: will only be executed if called from the datacage within a
felix@3244: longitudinal\_section diagram.
felix@3244: 
felix@3244: In the given example another concept of the datacage configuration is
felix@3244: encountered: Macros.
felix@3244: 
felix@3244: Macros help to avoid duplication of parts of the document.  As the datacage
felix@3244: of some diagrams should include the same type of data, the same query should
felix@3244: be executed in multiple situations.
felix@3244: 
felix@3244: Therefore a macro can be defined, like in
felix@3244: 
felix@3244: \begin{lstlisting}
felix@3244:         <dc:macro name="basedata_4_heightmarks-wq">
felix@3244:           <heightmarks>
felix@3244:             <dc:context>
felix@3244:               <dc:statement>
felix@3244:                 SELECT id          AS prot_id,
felix@3244:                        description AS prot_description
felix@3244:                 FROM wsts WHERE kind = 4 AND river_id = ${river_id}
felix@3244:               </dc:statement>
felix@3244:               <dc:elements>
felix@3244:               <!-- ... -->
felix@3244:         </dc:macro>
felix@3244: \end{lstlisting}
felix@3244: 
felix@3244: and invoked from another location within the document, e.g. with
felix@3244: 
felix@3244: \begin{lstlisting}
felix@3244: 
felix@3244:                 <dc:call-macro name="basedata_4_heightmarks"/>
felix@3244: \end{lstlisting}
felix@3244: .
felix@3244: 




