1. Graph Developer's Guide for Property Graph
  2. Using the Graph Server (PGX)
  3. Developing Applications with Graph Analytics
  4. Graph Management in the Graph Server (PGX)
  5. Publishing a Graph

15.2.3 Publishing a Graph

You can publish a graph that can be referenced by other sessions.

Publishing a Single Graph Snapshot

The PgxGraph#publish() method can be used to publish the current selected snapshot of the graph. The publish operation will move the graph name from the session-private namespace to the public namespace. If a graph with the same name has been already published, then the publish() method will fail with an exception. Graphs published with snapshots and single published snapshots share the same namespace.

Table 13-6 describes the grants required to publish a graph.

Note that calling the publish() method without arguments publishes the snapshot with its persistent properties only. However, if you want to publish specific transient properties, then you must list them within the publish() call as shown: 

opg4j> var prop1 = graph.createVertexProperty(PropertyType.INTEGER, "prop1")
opg4j> prop1.fill(0)
opg4j> var cost = graph.createEdgeProperty(PropertyType.DOUBLE, "cost")
opg4j> cost.fill(0d)
opg4j> graph.publish(List.of(prop1), List.of(cost))
VertexProperty<Integer, Integer> prop1 = graph.createVertexProperty(PropertyType.INTEGER, "prop1");
prop1.fill(0);
EdgeProperty<Double> cost = graph.createEdgeProperty(PropertyType.DOUBLE, "cost");
cost.fill(0d);
List<VertexProperty<Integer, Integer> vertexProps = Arrays.asList(prop);
List<EdgeProperty<Double>> edgeProps = Arrays.asList(cost);
graph.publish(vertexProps, edgeProps);

prop = graph.create_vertex_property("integer", "prop1")
prop1.fill(0)
cost = graph.create_edge_property("double", "cost")
cost.fill(0d)
vertex_props = [prop]
edge_props = [cost]
graph.publish(vertex_props, edge_props)

Publishing a Graph with Snapshots

If you want to make all snapshots of the graph visible to other sessions, then use the publishWithSnapshots() method. When a graph is published with snapshots, the GraphMetaData information of each snapshot is also made available to the other sessions, with the exception of the graph configuration, which is null.

When calling the publishWithSnapshots() method, all the persistent properties of all the snapshots are published and made visible to the other sessions. Transient properties are session-private and therefore they must be published explicitly. Once published, all properties become read-only.

Similar to publishing a single graph snapshot, the publishWithSnapshots() method will move the graph name from the session-private namespace to the public namespace. If a graph with the same name has been already published, then the publishWithSnapshots() method will fail with an exception.

Also, note that the published properties, like the original transient properties, are associated to the specific snapshot on which they were created. Therefore, they are not visible on other snapshots.

If you want to publish specific transient properties, you should list them within the publishWithSnapshots() call, as in the following example: 

opg4j> var prop1 = graph.createVertexProperty(PropertyType.INTEGER, "prop1")
opg4j> prop1.fill(0)
opg4j> var cost = graph.createEdgeProperty(PropertyType.DOUBLE, "cost")
opg4j> cost.fill(0d)
opg4j> graph.publishWithSnapshots(List.of(prop1), List.of(cost))
VertexProperty<Integer, Integer> prop1 = graph.createVertexProperty(PropertyType.INTEGER, "prop1");
prop1.fill(0);
EdgeProperty<Double> cost = graph.createEdgeProperty(PropertyType.DOUBLE, "cost");
cost.fill(0d);
List<VertexProperty<Integer, Integer> vertexProps = Arrays.asList(prop);
List<EdgeProperty<Double>> edgeProps = Arrays.asList(cost);
graph.publishWithSnapshots(vertexProps,edgeProps);
VertexProperty<Integer, Integer> prop1 = graph.createVertexProperty(PropertyType.INTEGER, "prop1")
prop1.fill(0)
EdgeProperty<Double> cost = graph.createEdgeProperty(PropertyType.DOUBLE, "cost")
cost.fill(0d)
List<VertexProperty<Integer, Integer> vertexProps = Arrays.asList(prop)
List<EdgeProperty<Double>> edgeProps = Arrays.asList(cost)
graph.publishWithSnapshots(vertexProps,edgeProps)

Referencing a Published Graph from Another Session

You can reference a published graph by its name in another session, using the PgxSession#getGraph() method.

The following example references a published graph myGraph in a new session (session2): 

opg4j> var session2 = instance.createSession("session2")
opg4j> var graph2 = session2.getGraph(Namespace.PUBLIC, "myGraph")
PgxSession session2 = instance.createSession("session2");
PgxGraph graph2 = session2.getGraph(Namespace.PUBLIC, "myGraph");
session2 = pypgx.get_session("session2");
PgxGraph graph2 = session2.get_graph("myGraph")

session2 can access only the published snapshot. If the graph has been published without snapshots, calling the getAvailableSnapshots() method will return an empty queue.

In case if the graph snapshots have been published, then the call to getGraph() returns the most recent available snapshot. session2 can see all the available snapshots through the getAvailableSnapshots() method. You can then set a specific snapshot using the PgxSession#setSnapshot() method.

Note:

If a referenced graph is not required anymore, then it is important that you release the graph. See Deleting a Graph for more information.

Publishing a Property

After publishing (a single snapshot or all of them), you can still publish transient properties individually. Published properties are associated to a specific snapshot on which they are created, and hence visible only on that snapshot.

opg4j> graph.getVertexProperty("prop1").publish()
opg4j> graph.getEdgeProperty("cost").publish()

graph.getVertexProperty("prop1").publish();
graph.getEdgeProperty("cost").publish();
graph.get_vertex_property("prop1").publish()
graph.get_edge_property("cost").publish()

Getting a Published Property in Another Session

Sessions referencing a published graph (with or without snapshots) can reference a published property through the PgxGraph#getVertexProperty and PgxGraph#getEdgeProperty. 
opg4j> var session2 = instance.createSession("session2")
opg4j> var graph2 = session2.getGraph(Namespace.PUBLIC, "myGraph")
opg4j> var vertexProperty = graph2.getVertexProperty("prop1")
opg4j> var edgeProperty = graph2.getEdgeProperty("cost")
PgxSession session2 = instance.createSession("session2");
PgxGraph graph2 = session2.getGraph(Namespace.PUBLIC, "myGraph");
VertexProperty<Integer, Integer> vertexProperty = graph2.getVertexProperty("prop1");
EdgeProperty<Double> edgeProperty = graph2.getEdgeProperty("cost");
session2 = pypgx.get_session(session_name ="session2")
graph2 = session2.get_graph("myGraph")
vertex_property = graph2.get_vertex_property("prop1")
edge_property = graph2.get_edge_property("cost")

Pinning a Published Graph

You can pin a published graph so that it remains published even if no session uses it.

opg4j> graph.pin()
graph.pin();
>>> graph.pin()

Unpinning a Published Graph

You can unpin a published graph that was earlier pinned. By doing this, you can remove the graph and all its snapshots, if no other session is using a snapshot of the graph.

opg4j> var graph = session.getGraph("bank_graph_analytics")
graph ==> PgxGraph[name=bank_graph_analytics,N=999,E=4993,created=1660217577201]
opg4j> graph.unpin()
PgxGraph graph = session.getGraph("bank_graph_analytics");
graph.unpin();
>>> graph = session.get_graph("bank_graph_analytics")
>>> graph.unpin()

Related Topics

Parent topic: Graph Management in the Graph Server (PGX)