report: add reference to other query paper

But not sure whether I'll follow through with it.

doc/report/applications.tex

@@ -273,6 +273,7 @@ existing exports have ``holes''.
 
 \subsection{Organizational Queries}\label{sec:miscq}
 
-\emph{{TODO}: SPARQL Queries references in ULO paper}
+Other organizational queries for organizational data sets have
+previously been proposed~\cite{adl}. Here we implement some of them.
 
 \subsection{Experience with Building a Web Frontend}\label{sec:webq}

doc/report/components.tex

+\section{Components}\label{sec:components}
+
+With ULO/RDF files in place and available for download on
+MathHub~\cite{uloisabelle, ulocoq} as Git repositories, we have the
+aim of making the underlying data available for use in applications.
+It makes sense to first identify the various components that might
+be involved in such a system. They are illustrated in
+figure~\ref{fig:components}.
+
+\begin{figure}[]\begin{center}
+    \includegraphics{figs/components}
+    \caption{Components involved in the \emph{ulo-storage} system.}\label{fig:components}
+\end{center}\end{figure}
+
+\begin{itemize}
+\item ULO data is present on various locations, be it Git
+  repositories, available on web servers or on the local disk.
+  Regardless where this ULO data is stored, it is the job of a
+  \emph{Collecter} to assemble these {RDF}~files and forward them
+  for further processing. This may involve cloning a Git repository or
+  crawling a file system.
+
+\item With streams of ULO files assembled by the Collecter, this
+  data then gets passed to an \emph{Importer}. An Importer uploads
+  received RDF~streams into some kind of permanent storage. For
+  use in this project, the GraphDB~\cite{graphdb} triplet store was
+  natural fit.
+
+  In this project, both Collecter and Importer ended up being one piece
+  of software, but this does not have to be the case.
+
+\item Finally, with all triplets stored in a database, an
+  \emph{Endpoint} is where applications access the underlying
+  knowledge base. This does not necessarily need to be any specific
+  software, rather the programming interface of the underlying
+  database itself could be understood as an endpoint of its
+  own.
+
+  Regardless, some thought can be put into designing an Endpoint as a
+  layer that lives between application and database that is more
+  convenient to use than the one provided by the database.
+\end{itemize}
+
+These are the components realized for \emph{ulo-storage}. Additionally
+to these components, one could think of a \emph{Harvester} component.
+We assumed that the ULO triplets are already available in RDF~format.
+Indeed for this project this was the case as we work with already
+exported triplets from the Isabelle and Coq libraries. However, this
+is not necessarily true.
+
+It might be desirable to automate the export from third party formats
+to ULO and we think this is what a Harvester should do.  It fetches
+mathematical knowledge from some remote source and then provides a
+volatile stream of ULO data to the Collecter, which then passes it
+to the Importer and so on. The big advantage of such an approach would
+be that exports from third party libraries can always be up to date
+and do not have to be initiated manually. We did not implement a Harvester
+for \emph{ulo-storage} but we suggest that it is an idea to keep in mind.
+
+Each component we did implement (Collecter, Importer, Endpoint) will
+now be discussed in a separate section. Here we only wanted to give
+the reader a general understanding in the infrastructure that makes
+up \emph{ulo-storage}.

doc/report/references.bib

@@ -188,12 +188,20 @@
 }
 
 @inproceedings{virt,
-  title={Virtual theories--a uniform interface to mathematical knowledge bases},
-  author={Wiesing, Tom and Kohlhase, Michael and Rabe, Florian},
-  booktitle={International Conference on Mathematical Aspects of Computer and Information Sciences},
-  pages={243--257},
-  year={2017},
-  organization={Springer},
-  url = {https://kwarc.info/people/frabe/Research/WKR_virtual_17.pdf},
-  urldate = {2020-07-09},
-}
+    title={Virtual theories--a uniform interface to mathematical knowledge bases},
+    author={Wiesing, Tom and Kohlhase, Michael and Rabe, Florian},
+    booktitle={International Conference on Mathematical Aspects of Computer and Information Sciences},
+    pages={243--257},
+    year={2017},
+    organization={Springer},
+    url = {https://kwarc.info/people/frabe/Research/WKR_virtual_17.pdf},
+    urldate = {2020-07-09},
+}
+
+@inproceedings{adl,
+    author = {Aspinall, David Denney, Ewen and Lüth Christoph},
+    title = {A semantic basis for proof queries and transformations},
+    booktitle = {International Conference on Logic for Programming Artificial Intelligence and Reasoning},
+    organization = {Springer},
+    year = {2013}
+}
\ No newline at end of file