OrientGraph db = new OrientGraph("memory:temp", "admin", "admin");
aVertex = db.addVertex("class:rawCategory");
aVertex.setProperty("name", "a");
bVertex = db.addVertex("class:rawCategory");
bVertex.setProperty("name", "b");
asubVertex = db.addVertex("class:rawField");
asubVertex.setProperty("name", "asub");
bsubVertex = db.addVertex("class:rawField");
bsubVertex.setProperty("name", "bsub");
asubVertex.addEdge("hasParent", aVertex);
bsubVertex.addEdge("hasParent", bVertex);