+ Summary
+ Medical and health informatics integrates knowledge of business
+ information systems, computer science and medicine. As a comparatively
+ young research discipline, it lacks a uniform terminology, especially
+ for describing health information systems and their management.
+ Several textbooks provide different perspectives of the discipline but
+ the linear struture inherent in a book does not intuitively convey the
+ highly connected nature of the concepts of the domain. SNIK
+ (Höffner
+ et al., 2017) is a semantic network of information management
+ in hospitals, which uses Semantic Web standards like RDF and OWL to
+ model and publish the knowledge of three textbooks
+ (Ammenwerth
+ et al., 2014;
+ Heinrich
+ et al., 2014;
+ Winter et
+ al., 2011), the IT4IT
+ (The
+ Open Group, 2017) standard and an interview with a hospital
+ CIO. Each of those sources is modelled according to the SNIK meta
+ model, which classifies each resource as being either a role, function
+ or entity type, see
+ [fig:metamodel].
+
+ The SNIK Meta
+ Model.
+ ![]()
+
+ SNIK Graph is a web-based interactive Linked Data graph
+ visualization of SNIK, which is based on Cytoscape.js
+ (Franz
+ et al., 2015), a JavaScript graph visualization and analysis
+ library. An installation visualizing SNIK is published at
+ https://www.snik.eu/graph
+ and
+ https://snikproject.github.io/graph,
+ but other ontologies and knowledge bases can be used as well. Due to
+ the large amount of resources, visualizing SNIK as a graph causes
+ overplotting as shown in
+ [fig:completegraph].
+ SNIK Graph offers several options to select and layout subgraphs in
+ multiple views
+ (Pause,
+ 2020), for example to show only a specific chapter of a book to
+ prepare a lecture about a specific topic.
+
+ Full view and subgraphs around information
+ management, systems and
+ project.
+ ![]()
+
+ A frequent question is, what a given role does and which
+ information is needed for those functions represented by the entity
+ types connected to those functions. This question is visually answered
+ by the class use feature, which arranges roles,
+ functions and entity types in concentric circles, see
+ [fig:roleuse].
+
+ Class use of the Chief Information
+ Officer. Entity types omitted for
+ brevity.
+ ![]()
+
+ Users can also iteratively explore SNIK starting at a single class
+ using neighbourhood and path operations. Exploration using neighbours,
+ that is the successive uncovering of nodes adjacent to a starting node
+ given by a user, is a common feature of tools such as LodLive
+ (Camarda
+ et al., 2012) and VizLOD
+ (Anutariya
+ & Dangol, 2018). The directed and undirected
+ star operations show nodes in the direct
+ neighbourhood of selected nodes. The circle star also
+ rearranges the nodes using the force-directed layout locally on the
+ currently visible subgraph.
+ [fig:star] shows a
+ mind map of a topic, created by an undirected star, which can be used
+ by a teacher to prepare a lecture about that topic.
+
+ Star of the 3LGM²-S model for service
+ oriented
+ communication.
+ ![]()
+
+ A spiderworm is a path from node A to node B
+ combined with a star of B.
+ [fig:spiderworm]
+ shows how we use a spiderworm to teach a student how the new concept
+ “quality of data” is connected the already introduced concept “patient
+ identification number.”
+
+ Spiderworm from Application
+ System to Application
+ Component.
+ ![]()
+
+
+
+ Statement of need
+ While students can access this knowledge in a structured way using
+ SNIK, this requires knowledge of Semantic Web technologies like SPARQL
+ queries. The main goal of SNIK Graph is to visualize SNIK to users
+ that may not have any Semantic Web experience. Graph-based
+ visualizations allow teachers to intuitively convey relationships
+ between a selection of those concepts and also allow students to
+ explore the domain on their own
+ (Jahn
+ et al., 2016). There are several existing graph-based Linked
+ Data visualizations
+ (Po
+ et al., 2020), which visualize RDF resources (classes or
+ instances) as nodes and their relationships as edges, but they do not
+ fit our requirements
+ (Schaaf
+ et al., 2016).
+
+
+ Future work
+ The single-thread paradigm of JavaScript seriously hinders
+ performance of CPU-bound applications like SNIK Graph on the more than
+ 4000 resources of SNIK. While SNIK Graph does not require perfectly
+ smooth motion, and wild movements are not a common usage pattern,
+ stuttering is still frustrating to users especially on less performant
+ CPUs and browsers other than Chrome, which is contrary to our goal of
+ minimizing friction for users. Implementing an OpenGL-based renderer
+ for Cytoscape.js may dramatically increase render speed.
+ The search index is implemented using the Fuse.js
+ (Risk,
+ 2021) client-side library based on the Baeza-Yates–Gonnet
+ algorithm
+ (Baeza-Yates
+ & Gonnet, 1992). This enables fuzzy search on any dataset
+ loaded via SPARQL endpoint without needing a backend search index like
+ Elasticsearch but requires waiting for index initialization on the
+ first search of each user session and is not fast enough for
+ autocompletion, even with debouncing and throttling. Adding a separate
+ search backend will provide much faster initialization and search.
+
+