Using TinkerPop Framework for CRUD Operations on GDB

Due to the need to process and store graph data in the business, GDB was chosen as the repository. Most of the official examples from GDB involve directly submitting string-type scripts (Script) for CRUD operations on the database. However:

1. Many initial filtering conditions for business logic are similar, and subsequent operations are dispersed. Since Gremlin syntax resembles chain operations, directly using string concatenation cannot predict the data type returned from the previous step in the code, leading to missing or incorrect logic in the code;

2. Node writing and edge addition operations rely on complex business deduplication logic, which need to be wrapped in transactions, but the official documentation does not provide examples of transaction operations;

3. Some APIs provided by TinkerPop cannot be used on GDB, resulting in strange errors (e.g., SessionedClient, tx, Transaction, etc.).

Additionally, my backend coding skills need improvement; the example’s layering is for reference only, and corrections and discussions are welcome [manual dog head].

<dependency>  <groupId>org.apache.tinkerpop</groupId>  <artifactId>gremlin-annotations</artifactId>  <version>3.6.0</version><!-- It is best to align the version number with GdbClient's dependency --></dependency>

@GremlinDslpublic interface SocialTraversalDsl<S, E> extends GraphTraversal.Admin<S, E> {    public default GraphTraversal<S, Vertex> knows(String personName) {        return out("knows").hasLabel("person").has("name", personName);    }            public default <E2 extends Number> GraphTraversal<S, E2> youngestFriendsAge() {        return out("knows").hasLabel("person").values("age").min();    }            public default GraphTraversal<S, Long> createdAtLeast(int number) {        return outE("created").count().is(P.gte(number));    }}

SocialTraversalSource social = traversal(SocialTraversalSource.class).withEmbedded(graph);social.V().has("name","marko").knows("josh");

Here, through transactional/non-transactional business operations, we connect the necessary DAOs.

In the TinkerPop framework, a single no Session submission to the client is equivalent to a transaction processing; if an error occurs during computation, the entire statement does not take effect.

By using the g.tx() method, a Transaction can be obtained for manual management of multiple statements execution, with operations for transaction begin, commit, close, and rollback, enabling the opening, committing, closing, and rolling back of transactions.

Therefore, in the Service layer, operations are divided into NoSession operations and Session operations based on whether transactions are needed.

Generally, create, modify, and delete operations are categorized as Session operations (because they need to determine whether to execute subsequent operations based on the success of the previous query’s conditions), especially for insert operations, which require the insertion of points and corresponding relationship edges. Until the point insertion is successful, the point’s ID cannot be known, thus preventing direct continuous operations from completing the edge insertion—only two separate operations can be used to accomplish this.

No Session operations will not be elaborated here; they only need to be submitted according to the complete Script or Bytecode and obtain execution results.

▐ TinkerPop Official Usage Methods

According to the official example, when the database supports transactions, we can use g.tx() to obtain a Transaction object. Then, through the Transaction object’s begin method, a new GraphTraversalSource object can be obtained for coherent operations. This object can be used multiple times for CRUD operations, and results can be obtained for logical judgments. Finally, commit or rollback can be chosen to confirm or roll back operations.

As shown in the following example:

GraphTraversalSource g = traversal().withRemote(conn);Transaction tx = g.tx();// spawn a GraphTraversalSource from the Transaction. Traversals spawned// from gtx will be essentially be bound to tx// Start transactionGraphTraversalSource gtx = tx.begin();try {    //Add vertex 1    List<Vertex> personResult = gtx.addV("person").property("name", "John").toList();    Assert.isTrue(!CollectionUtils.isEmpty(personResult), "Failed in create PersonNode");    //Add vertex 2    List<Vertex> softwareResult = gtx.addV("software").property("name", "YYDS").toList();    Assert.isTrue(!CollectionUtils.isEmpty(personResult), "Failed in create SoftwareNode");    //Add relationship from vertex 1 to vertex 2    List<Edge> edgeCreateResult = gtx.addE("create")      .from(gtx.V(personResult.get(0).id())).to(gtx.V(softwareResult.get(0).id())).toList();    //Submit result    tx.commit();    log.info("Success create Record [{} -create-> {}]", "John", "YYDS");    return edgeCreateResult.get(0);} catch (Exception ex) {    //Rollback transaction    tx.rollback();    throw ex;} finally {    tx.close();}