The Major Differences Between Blueprints 1.x and 2.x
Blueprints 2 introduced numerous changes to the Blueprints API. This page helps to explain these differences so updating code from Blueprints 1.x to Blueprints 2.x is as easy as possible.
In the early days of Blueprints, there were two notions:
- Property Graphs Model
- Object Document Model
To account for these two models, there were two packages: com.tinkerpop.blueprints.pgm and com.tinkerpop.blueprints.odm. Blueprints has since focused solely on the property graph model and as such, in Blueprints 2.x, there is no more pgm, it is simply com.tinkerpop.blueprints.
There is no more notion of AutomaticIndex in Blueprints 2. Many graph databases such as DexGraph, IGGraph, and TitanGraph do not support the notion of arbitrary indexing. Instead, they simply allow an element to be indexed by its key/value property pairs. As such, KeyIndexableGraph provides an interface to this basic indexing functionality (see Graph Indices). To index a the name key of all vertices, simply do:
graph.createKeyIndex("name", Vertex.class);Now, when graph.getVertices("name", "stephen") is evaluated, the name index is used. If no such key index was created, then a linear scan of all the vertices in the graph would occur. Thus, be sure to add the appropriate indices to make an n-lookup a log(n)-lookup.
For “manual indexing,” there is still the notion of IndexableGraph and the Index class. This is used by graph engines like Neo4jGraph, OrientGraph, and TinkerGraph.
In Blueprints 1.x, there existed the following Vertex methods.
Vertex.getOutEdges(String... labels)
Vertex.getInEdges(String... labels)As of Blueprints 2.x, there are now the following Vertex methods.
Vertex.getEdges(Direction direction, String... labels)
Vertex.getVertices(Direction direction, String... labels)With Vertex.getEdges(), it is possible to get the incoming, outgoing, or both incident edges to a vertex filtered by their edge label. With Vertex.getVertices(), it is possible to get the incoming, outgoing, or both adjacent vertices to a vertex filtered by the edge label of the adjoining edges. Likewise, in a similar fashion, Edge has been updated with the following method.
Edge.getVertex(Direction direction)There is a new method in the Vertex class called Vertex.query(). This method returns a Query object that has a fluent interface. They Query object is a way of intelligently selecting adjacent vertices or incident edges to a vertex. Please learn more about Query on the Vertex Query wiki page.