Advanced Graph View

The RDF Graph Query UI supports an advanced graph view feature that allows users to interact directly with the graph visualization. This is unlike the graph displayed on the RDF model editor or public component where the graph view is just an output of the SPARQL results on the paging table.

This section describes the advanced graph view component, starting from the execution of a SPARQL CONSTRUCT or SPARQL DESCRIBE query to advanced interaction with the graph visualization.

The main user interface (UI) elements of the advanced graph view component are as shown:

Figure: Advanced Graph View Components

Description of the illustration adv_graph_view_page.png

The following describes the UI components seen in the preceding figure:

• SPARQL Query selector contains a text area with the SPARQL query (must be SPARQL CONSTRUCT or SPARQL DESCRIBE).

• A Graphviz area that displays the graph with the RDF vertices and edges.

To access the advanced graph view feature, right-click on the RDF model and select Visualize as shown:

Figure: Visualize Menu

Description of the illustration adv_graph_view_visualize_menu.png

• Query Selector Panel

• Graphviz

Query Selector Panel

To start using the advanced graph view feature, you must first execute a SPARQL CONSTRUCT or SPARQL DESCRIBE query. The Query Selector also provides an Options input box to specify the query options to be used when executing queries in the visualizer. The supported query options are described in Using the SEM_MATCH Table Function to Query RDF Data. The resulting query output is displayed as an interactive graph in the Graphviz component.

The system may automatically run additional queries to build the graph before it is displayed. A SPARQL query is executed for each resource in the initial query result set to retrieve values for its datatype properties. These additional queries ensure that each vertex in the graph is fully populated with its attributes. The maximum number of resources that can be expanded in a result set is 2,000. The application will raise an error if this limit is exceeded. In which case, you can reduce the result set size by using a more selective SPARQL query or using a LIMIT clause.

The following figure shows an example SPARQL CONSTRUCT query that describes the person named George in a PEOPLE dataset. The Query Selector Panel can be collapsed to provide more space for interacting with the graph.

Figure: Query Selector

Description of the illustration adv_graph_view_query_selector.png

Graphviz

The graph is displayed in the Graphviz panel and the visualization is based on the Graph Visualization Library. See Graph Visualization Library Reference in Property Graph Visualization Developer’s Guide and Reference for more information.

The displayed graph is constructed from an RDF graph as follows.

• URI and blank node resources are shown as vertices and hold their rdf:type class membership information in a labels array, which is used for the graph legend. Each vertex has a shortName property that is used to label the vertex in the display graph. The shortName property is populated in the following priority:

  1. rdfs:label value of the resource

  2. skos:prefLabel value of the resource

  3. Local name portion of the resource’s URI or its blank node label

  If multiple rdfs:label or skos:prefLabel values exist for the same resource, plain literal values are selected first, followed by en-tagged literals, followed by any other value. Data type properties for these URIs and blank nodes are shown as vertex properties.

• Object properties are shown as edges connecting two vertices. These edges use the local name portion of the RDF predicate URI as the edge label for both the graph legend and the edge display label. Edges hold properties for full predicate URI, source (subject) RDF term and target (object) RDF term.

The Graphviz panel consists of the following components:

• A toolbar with the following options (described in order from left to right):

  Figure: Graph Visualization Toolbar

  

  Description of the illustration adv_graph_view_gviz_toolbar.png

  • Move/Zoom: This mode allows you to zoom in and out, as well as to move to another part of the visualization.

  • Fit to Screen: This mode fits the resulting graph in the graph visualization view.

  • Toggles Sticky Mode: This mode allows you to cancel the action of moving the nodes around.

  • Graph Manipulation: This mode allows you to interact with your graph visualization.

    The following actions are supported:

    • Expand: To expand selected vertices from the visualization.

    • Drop: To remove selected vertices from the visualization. Alternatively, you can also execute this from the tooltip.

    • Group: To group selected multiple vertices and collapse them into a single one.

    • Ungroup: To select a group of collapsed vertices and ungroup them.

    • Undo: To undo the last action.

    • Redo: To redo the last action.

    • Reset: To reset the visualization to the original state after the query.

• A drawing area with the RDF nodes and edges.

• A graph legend on the right side of the panel that displays vertex and edge types and their associated styles in the graph.

  Figure: Graph Legend Panel

  

  Description of the illustration adv_graph_view_gviz_legend.png

• A layout selector at the bottom of the display panel that provides various layout options for positioning vertices and edges on the display.

  Figure: Layout Selector

  

  Description of the illustration adv_graph_view_gviz_layout.png

You can interact with the edges and vertices of the graph displayed in the graph view area.

You can right-click on a vertex to view its datatype properties. The following figure shows the datatype property values for the vertex representing the person Craig.

Figure: Viewing Vertex Properties

Description of the illustration adv_graph_view_display_vertex_prop.png

You can also right-click on an edge to show its properties. The following figure shows the edge properties for the worksFor edge:

Figure: Viewing Edge Properties

Description of the illustration adv_graph_view_display_edge_prop.png

To expand a vertex in the graph, right-click on the vertex and then click the expand icon. New vertices and edges directly connected to the expanded vertex will be added to the graph. For example, in the following figure, vertex Julie is shown expanded:

Figure: Expanding a Vertex

Description of the illustration adv_graph_view_expand.png