content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.datastax.dse.driver.api.core.graph;
  
  import com.datastax.oss.driver.api.core.CqlSession;
  import com.datastax.oss.driver.api.core.session.Session;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.util.Objects;
  import java.util.concurrent.CompletionStage;
  
  /**
   * A session that has the ability to execute DSE Graph requests.
   *
   * <p>Generally this interface won't be referenced directly in an application; instead, you should
   * use {@link CqlSession}, which is a combination of this interface and many others for a more
   * integrated usage of DataStax Enterprise's multi-model database via a single entry point. However,
   * it is still possible to cast a {@code CqlSession} to a {@code GraphSession} to only expose the
   * DSE Graph execution methods.
   */
  public interface GraphSession extends Session {
  
    /**
     * Executes a graph statement synchronously (the calling thread blocks until the result becomes
     * available).
     *
     * <p>The driver provides different kinds of graph statements:
     *
     * <ul>
     *   <li>{@link FluentGraphStatement} (recommended): wraps a fluent TinkerPop {@linkplain
     *       org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal traversal};
     *   <li>{@link BatchGraphStatement}: groups together multiple mutating traversals ({@code
     *       g.addV()/g.addE()}) inside a single transaction and avoids multiple client-server
     *       round-trips. Improves performance in data ingestion scenarios;
     *   <li>{@link ScriptGraphStatement}: wraps a Gremlin-groovy script provided as a plain Java
     *       string. Required for administrative queries such as creating/dropping a graph,
     *       configuration and schema.
     * </ul>
     *
     * <p>This feature is only available with DataStax Enterprise. Executing graph queries against an
     * Apache Cassandra&reg; cluster will result in a runtime error.
     *
     * @see GraphResultSet
     * @param graphStatement the graph query to execute (that can be any {@code GraphStatement}).
     * @return the result of the graph query. That result will never be null but can be empty.
     */
    @NonNull
    default GraphResultSet execute(@NonNull GraphStatement<?> graphStatement) {
      return Objects.requireNonNull(
          execute(graphStatement, GraphStatement.SYNC),
          "The graph processor should never return a null result");
    }
  
    /**
     * Executes a graph statement asynchronously (the call returns as soon as the statement was sent,
     * generally before the result is available).
     *
     * <p>This feature is only available with DataStax Enterprise. Executing graph queries against an
     * Apache Cassandra&reg; cluster will result in a runtime error.
     *
     * @see #execute(GraphStatement)
     * @see AsyncGraphResultSet
     * @param graphStatement the graph query to execute (that can be any {@code GraphStatement}).
     * @return the {@code CompletionStage} on the result of the graph query.
     */
    @NonNull
    default CompletionStage<AsyncGraphResultSet> executeAsync(
        @NonNull GraphStatement<?> graphStatement) {
      return Objects.requireNonNull(
          execute(graphStatement, GraphStatement.ASYNC),
          "The graph processor should never return a null result");
    }
  }
  