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ASF GitHub Bot commented on TINKERPOP-1750: ------------------------------------------- GitHub user karthicks opened a pull request: https://github.com/apache/tinkerpop/pull/693 TINKERPOP-1750: An Object Graph Mapping Framework For Gremlin. This pull request implements the object-graph mapping framework proposed in [TINKERPOP-1750](https://issues.apache.org/jira/browse/TINKERPOP-1750). In addition to the proposed framework, a reference implementation based on `TinkerGraph` is included. It comes with test cases, and is `javadoc` friendly. A license for `lombok` was added to the `LICENSE` file. For more details, please see the [README](./gremlin-objects/README.asciidoc) under the `gremlin-objects` module. You can merge this pull request into a Git repository by running: $ git pull https://github.com/karthicks/tinkerpop TINKERPOP-1750 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/tinkerpop/pull/693.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #693 ---- commit df6474dda72cd8718af9b7686a52e46d05c20014 Author: Karthick Sankarachary <karth...@elementum.com> Date: 2017-08-13T03:31:23Z TINKERPOP-1750 An Object Graph Mapping Framework For Gremlin. ---- > An Object Graph Mapping Framework For Gremlin > --------------------------------------------- > > Key: TINKERPOP-1750 > URL: https://issues.apache.org/jira/browse/TINKERPOP-1750 > Project: TinkerPop > Issue Type: Improvement > Components: structure, tinkergraph > Affects Versions: 3.3.0 > Reporter: Karthick Sankarachary > > Here, we describe a framework that puts an object-oriented spin on the > Gremlin property graph. It aims to make it much easier to specify business > {{DSLs}} around Gremlin. > h5. Object Model > Every element in the property graph, whether it be a vertex (property) or an > edge, is made up of properties, each of which is a {{String}} key and an > arbitrary {{Java}} value. It only seems fitting then to try and represent > that property as a strongly-typed {{Java}} field. The specific class in which > that field is defined then becomes the vertex (property) or edge. > Let's consider the example of the {{person}} vertex, taken from the > {{TinkerFactory}}. In our object world, it would be defined as a {{Person}} > class that extends a {{Vertex}} class like so: > {code:java} > @Data > @Alias(label = "person") > public class Person extends Vertex { > public static ToVertex KnowsPeople = traversal -> traversal > .out(Label.of(Knows.class)) > .hasLabel(Label.of(Person.class)); > @PrimaryKey > private String name; > @OrderingKey > private int age; > private Set<String> titles; > private List<Location> locations; > } > {code} > The person's {{name}} and {{age}} properties become primitive fields in the > class. The {{KnowsPeople}} field in this class is an example of an in-line > {{SubTraversal}}, which is just a reusable function that performs certain > steps on a {{GraphTraversal}}. > Its {{titles}} field, which is defined to be a {{Set}}, takes on the {{set}} > cardinality. Similarly, the {{locations}} field gets the {{list}} > cardinality. Since each {{location}} has it's own meta-properties, it > deserves a {{Location}} class of it's own. > {code:java} > @Data > public class Location extends Element { > @OrderingKey > @PropertyValue > private String name; > @OrderingKey > private Instant startTime; > private Instant endTime; > } > {code} > The value of the {{location}} is stored in {{name}}, due to the placement of > the {{@PropertyValue}} annotation. Every other field in that class becomes > the {{location's}} meta-property. > h5. Updating Objects > The {{Graph}} interface lets you update the graph using {{Vertex}} or > {{Edge}} objects. Below, a {{person}} vertex containing a list of > {{locations}} is added, along with three outgoing edges. > {code:java} > graph > .addVertex( > Person.of("marko", > Location.of("san diego", 1997, 2001), > Location.of("santa cruz", 2001, 2004), > Location.of("brussels", 2004, 2005), > Location.of("santa fe", 2005))).as("marko") > .addEdge(Develops.of(2010), "tinkergraph") > .addEdge(Uses.of(Proficient), "gremlin") > .addEdge(Uses.of(Expert), "tinkergraph") > {code} > Since the object being added may already exist in the graph, we provide > various ways to resolve "merge conflicts", such as {{MERGE}}, {{REPLACE}}, > {{CREATE}}, {{IGNORE}} and {{INSERT}}. > h5. Querying Objects > Next, let's see how to use the {{Query}} interface. The following snippet > queries the graph by a chain of {{SubTraversals}}, and parses the result into > a list of {{Person}} vertices. > {code:java} > List<Person> friends = query > .by(HasKeys.of(modern.marko), Person.KnowsPeople) > .list(Person.class); > {code} > Below, we query by an {{AnyTraversal}} (a function on the > {{GraphTraversalSource}}), and get a single {{Person}} back. > {code:java} > Person marko = Person.of("marko"); > Person actual = query > .by(g -> g.V().hasLabel(marko.label()).has("name", marko.getName())) > .one(Person.class); > {code} > h5. Service Provider Interface > To become a {{gremlin-objects}} provider, you would need to implement the > {{GraphSystem}}, which supplies a {{GraphTraversalSource}}. And then, extend > the {{ObjectGraph}} and {{ObjectQuery}} abstract classes, constructor > injecting your {{GraphSystem}}. > For more details, please see the readme file in the the pull request that I'm > about to submit, which also comes with a reference implementation based on > {{TinkerGraph}}. While I also have a {{DataStax}} implementation, which we > use at Elementum, a supply chain graph company, it isn't included since it > depends on an older TinkerPop version. -- This message was sent by Atlassian JIRA (v6.4.14#64029)