Edge labels are used to define semantics of the relationship between two vertexes. Edge label name must be unique within the graph.
For example, the edge labelled knows between two vertexes v1 and v2 encodes a relationship between two persons.
You can set the multiplicity of edges between vertices for a given label while defining edge label. Below table summarizes different possible multiplicity options.
|
Multiplicity |
Description |
|
MULTI |
Allows multiple edges of the same label between any pair of vertices. This is used to define multigraphs. |
|
SIMPLE |
Allows at most one edge of such label between any pair of vertices. |
|
MANY2ONE |
There can only be a single out-edge of this label for a given vertex but multiple in-edges. (i.e. out-unique) |
|
ONE2MANY |
There can only be a single in-edge of this label for a given vertex but multiple out-edges (i.e. in-unique) |
|
ONE2ONE |
There can be only a single in and out-edge of this label for a given vertex (i.e. unique in both directions). |
Example
EdgeLabelMaker edgeLabelMaker = janusGraphManagement.makeEdgeLabel("knows");
edgeLabelMaker.multiplicity(Multiplicity.SIMPLE);
edgeLabelMaker.make();
Above snippet defines a label ‘knows’.
Find the below working application.
ModelEdgeLabel.java
package com.sample.app.schema;
import org.janusgraph.core.EdgeLabel;
import org.janusgraph.core.JanusGraph;
import org.janusgraph.core.JanusGraphFactory;
import org.janusgraph.core.Multiplicity;
import org.janusgraph.core.schema.EdgeLabelMaker;
import org.janusgraph.core.schema.JanusGraphManagement;
public class ModelEdgeLabel {
public static void main(String args[]) {
try (JanusGraph janusGraph = JanusGraphFactory.open("/Users/Shared/janus.properties")) {
JanusGraphManagement janusGraphManagement = janusGraph.openManagement();
EdgeLabelMaker edgeLabelMaker = janusGraphManagement.makeEdgeLabel("knows");
edgeLabelMaker.multiplicity(Multiplicity.SIMPLE);
EdgeLabel edgeLabel = edgeLabelMaker.make();
String schema = janusGraphManagement.printSchema();
System.out.println(schema);
} finally {
System.out.println("\nDone!!!");
}
}
}
Output
------------------------------------------------------------------------------------------------ Vertex Label Name | Partitioned | Static | --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- Edge Label Name | Directed | Unidirected | Multiplicity | --------------------------------------------------------------------------------------------------- knows | true | false | SIMPLE | --------------------------------------------------------------------------------------------------- Property Key Name | Cardinality | Data Type | --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- Graph Index (Vertex) | Type | Unique | Backing | Key: Status | --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- Graph Index (Edge) | Type | Unique | Backing | Key: Status | --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- Relation Index (VCI) | Type | Direction | Sort Key | Order | Status | --------------------------------------------------------------------------------------------------- Done!!!
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