GSoC 18' Update 4: SPARQL
This week was all about improving the Graph Explorer.
Learning SPARQL
Before making changes to the core functionality of the Graph Explorer, I wanted to make myself familiar with SPARQL queries.
I used this tutorial.
Allowing to show incoming links in the Graph Explorer
In the existing state of the Graph Explorer, a user can see and expand outgoing links but not incoming links. I added this feature to make exploration of the query results more informative for users.
Implementation
I wrote 2 new SPARQL queries to allow incoming links on the explorer to be shown. Showing both incoming and outgoing links at once would have made the explorer too crowded so I added a toggle switch to see either incoming or outgoing links using Bootstrap Toggle.
One issue I ran into was in the case of incoming links that number more than 50. This would crowd the Explorer Dialog and fetching such a large number of nodes at once would affect performance significantly.
To handle this problem, I added an extra node (of a different colour) that indicates the number of unexpanded nodes.
I also added hierarchical layout options to the graph explorer, similar to the graph result browser. This is accompanied by a ‘Fit-to-Screen’ button that resizes the visualisation to fit the window.
What’s Next?
- Finding other ways to improve the UX of the Graph Explorer
eg. Navigation Buttons (left, right, up, down, zoom) - Ensuring that the features written this week are production-ready.