diff --git a/doc/report/endpoints.tex b/doc/report/endpoints.tex
index db66855c11e44b6f1d0ccb15b5ed327a77172f3a..8fe03e5726260e85d6b1b8df09be27084cd79780 100644
--- a/doc/report/endpoints.tex
+++ b/doc/report/endpoints.tex
@@ -12,63 +12,63 @@ one based around the standardized SPARQL query language and the other
on the RDF4J Java library implemented by various vendors. Both
approaches have unique advantages.
-\subsection{Available Application Interfaces}
+\begin{description}
+ \item[SPARQL] is a standardized query language for RDF triplet
+ data~\cite{sparql}. The specification includes not just syntax
+ and semantics of the language itself, but also a standardized
+ REST interface for querying databases.
-\begin{itemize}
- \item SPARQL is a standardized query language for RDF triplet
- data~\cite{sparql}. The spec includes not just syntax and
- semantics of the language itself, but also a standardized REST
- interface for querying databases. Various implementations of
- this standard, e.g.~\cite{gosparql}, are available so using
- SPARQL has the advantage of making us independent of a specific
- programming language or environment.
-
- SPARQL is inspired by SQL and as such the \texttt{SELECT}
- \texttt{WHERE} syntax should be familiar to many software
- developers. A simple query that returns all triplets in the
- store looks like
- \begin{verbatim}
- SELECT * WHERE { ?s ?p ?o }
- \end{verbatim}
+ \textbf{Syntax} SPARQL is inspired by SQL and as such the
+ \texttt{SELECT} \texttt{WHERE} syntax should be familiar to many
+ software developers. A simple query that returns all triplets
+ in the store looks like
+ \begin{lstlisting}
+ SELECT * WHERE { ?s ?p ?o }
+ \end{lstlisting}
where \texttt{?s}, \texttt{?p} and \texttt{?o} are query
- variables. The result of a query are valid substitutions for the
- query variables. In this case, the database would return a table
- of all triplets in the store sorted by subject~\texttt{?o},
- predicate~\texttt{?p} and object~\texttt{?o}.
+ variables. The result of any query are valid substitutions for
+ the query variables. In this particular case, the database would
+ return a table of all triplets in the store sorted by
+ subject~\texttt{?o}, predicate~\texttt{?p} and
+ object~\texttt{?o}.
- Of course, queries might return a lot of data. Importing just
- the Isabelle exports into GraphDB results in more than 200
- million triplets. For practical applications it will be
- necessary to limit the number of result or use pagination
- techniques~\cite{sparqlpagination}.
+ \textbf{Advantage} Probably the biggest advantage is that
+ SPARQL is ubiquitous. As it is the de facto standard for
+ querying triplet stores, lots of literature and documentation is
+ available~\cite{sparqlbook, sparqlimpls, gosparql}.
- \item RDF4J is a Java API for interacting with triplet stores,
- implemented based on a superset of
- {SPARQL}~\cite{rdf4j}. GraphDB supports RDF4J, in fact it is the
- recommended way of interacting with GraphDB
- repositories~\cite{graphdbapi}. Instead of formulating textual
- queries, RDF4J allows developers to query a repository by
- calling Java API methods. Above query that returns all triplets
- in the store looks like
- \begin{verbatim}
- connection.getStatements(null, null, null);
- \end{verbatim}
- in RDF4J. Method \texttt{getStatements(s, p, o)} returns all
- triplets that have matching subject~\texttt{s},
- predicate~\texttt{p} and object~\texttt{o}. If any of these
- arguments is \texttt{null}, it can be any value, i.e.\ it is a
- query variable that is to be filled by the call to
- \texttt{getStatements}.
+ \item[RDF4J] is a Java API for interacting with triplet stores,
+ implemented based on a superset of the {SPARQL} REST interface~\cite{rdf4j}.
+ GraphDB supports RDF4J, in fact it is the recommended way of
+ interacting with GraphDB repositories~\cite{graphdbapi}.
- Using RDF4J does introduce a dependency on the JVM family of
- languages, but also offers some conveniences. For example, we
- can generate Java classes that contain all URIs in an OWL
- ontology as constants~\cite{rdf4jgen}. In combination with IDE
- support, we found this to be very convenient when writing
- applications that interface with ULO data sets.
+ \textbf{Syntax} Instead of formulating textual queries, RDF4J
+ allows developers to query a repository by calling Java API
+ methods. Previous query that requests all triplets in the store
+ looks like
+ \begin{lstlisting}
+ connection.getStatements(null, null, null);
+ \end{lstlisting}
+ in RDF4J. \texttt{getStatements(s, p, o)} returns all triplets
+ that have matching subject~\texttt{s}, predicate~\texttt{p} and
+ object~\texttt{o}. Any argument that is \texttt{null} can be
+ replace with any value, i.e.\ it is a query variable to be
+ filled by the call to \texttt{getStatements}.
-\end{itemize}
+ \textbf{Advantage} Using RDF4J does introduce a dependency on
+ the JVM and its languages. But in practice, we found RDF4J to be
+ quite convenient, especially for simple queries, as it allows us
+ to formulate everything in a single programming language rather
+ than mixing languages and awkward string literals.
-\subsection{Comparison}
+ We also found it quite helpful to generate Java classes from
+ OWL ontologies that contain all definitions of the ontology and
+ make it readable by any IDE~\cite{rdf4jgen}.
+\end{description}
-\emph{TODO}
+We see that both SPARQL and RDF4J have unique advantages. While SPARQL
+is an official W3C standard and implemented by more database systems,
+RDF4J can be more convenient when dealing with JVM-based code bases.
+For \emph{ulo-storage}, we played around with both interfaces and
+chose whatever seemed more convenient at the moment. We recommend any
+implementors to do the same.
diff --git a/doc/report/references.bib b/doc/report/references.bib
index 4a0ec1110f4df2214c7c6b160b156fe820a39052..9560db2112eae989deff1487f8120d3598370be1 100644
--- a/doc/report/references.bib
+++ b/doc/report/references.bib
@@ -14,6 +14,13 @@
url = {https://godoc.org/github.com/knakk/sparql},
}
+@online{sparqlimpls,
+ title = {SparqlImplementations},
+ organization = {W3C},
+ url = {https://www.w3.org/wiki/SparqlImplementations},
+ urldate = {2020-07-06},
+}
+
@online{uloisabelle,
title = {Isabelle: Libraries of the Isabelle proof assistant in OMDoc/MMT representation},
organization = {MathHub},
@@ -140,3 +147,10 @@
urldate = {2020-07-06},
url = {https://kwarc.info/people/frabe/Research/GKKMR_alignments_17.pdf},
}
+
+@book{sparqlbook,
+ title={Learning SPARQL: querying and updating with SPARQL 1.1},
+ author={DuCharme, Bob},
+ year={2013},
+ publisher={" O'Reilly Media, Inc."}
+}