[jira] [Commented] (TINKERPOP-1750) An Object Graph Mapping Framework For Gremlin

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-1750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16125007#comment-16125007 ] 

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 <ka...@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.



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