I haven't been able to find a comprehensive example of connecting to and then querying a remote Apache Tinkerpop Graph Database with Gremlin and Java. And I can't quite get it to work. Can anyone that's done something like this before offer any advice?
I've set up a Azure Cosmos database in Graph-DB mode, which is expecting Gremlin queries in order to modify and access its data. I have the database host name, port, username, and password, and I'm able to execute queries, but only if I pass in a big ugly query string. I would like to be able to leverage the org.apache.tinkerpop.gremlin.structure.Graph traversal methods, but I can't quite get it working.
import java.util.List;
import java.util.concurrent.CompletableFuture;
import org.apache.tinkerpop.gremlin.driver.Result;
import org.apache.tinkerpop.gremlin.driver.ResultSet;
import org.apache.tinkerpop.gremlin.structure.Graph;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
//More imports...
@Service
public class SearchService {
private final static Logger log = LoggerFactory.getLogger(SearchService.class);
@Autowired
private GraphDbConnection graphDbConnection;
@Autowired
private Graph graph;
public Object workingQuery() {
try {
String query = "g.V('1234').outE('related').inV().both().as('v').project('vertex').by(select('v')).by(bothE().fold())";
log.info("Submitting this Gremlin query: {}", query);
ResultSet results = graphDbConnection.executeQuery(query);
CompletableFuture<List<Result>> completableFutureResults = results.all();
List<Result> resultList = completableFutureResults.get();
Result result = resultList.get(0);
log.info("Query result: {}", result.toString());
return result.toString();
} catch (Exception e) {
log.error("Error fetching data.", e);
}
return null;
}
public Object failingQuery() {
return graph.traversal().V(1234).outE("related").inV()
.both().as("v").project("vertex").by("v").bothE().fold()
.next();
/* I get an Exception:
"org.apache.tinkerpop.gremlin.process.remote.RemoteConnectionException:
java.lang.RuntimeException: java.lang.RuntimeException:
java.util.concurrent.TimeoutException: Timed out while waiting for an
available host - check the client configuration and connectivity to the
server if this message persists" */
}
}
This is my configuration class:
import java.util.HashMap;
import java.util.Map;
import org.apache.tinkerpop.gremlin.driver.Cluster;
import org.apache.tinkerpop.gremlin.driver.MessageSerializer;
import org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection;
import org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV2d0;
import org.apache.tinkerpop.gremlin.structure.Graph;
import org.apache.tinkerpop.gremlin.structure.util.GraphFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class GraphDbConfig {
private final static Logger log = LoggerFactory.getLogger(GraphDbConfig.class);
@Value("${item.graph.hostName}")
private String hostName;
@Value("${item.graph.port}")
private int port;
@Value("${item.graph.username}")
private String username;
@Value("${item.graph.password}")
private String password;
@Value("${item.graph.enableSsl}")
private boolean enableSsl;
@Bean
public Graph graph() {
Map<String, String> graphConfig = new HashMap<>();
graphConfig.put("gremlin.graph",
"org.apache.tinkerpop.gremlin.process.remote.RemoteGraph");
graphConfig.put("gremlin.remoteGraph.remoteConnectionClass",
"org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection");
Graph g = GraphFactory.open(graphConfig);
g.traversal().withRemote(DriverRemoteConnection.using(cluster()));
return g;
}
@Bean
public Cluster cluster() {
Cluster cluster = null;
try {
MessageSerializer serializer = new GraphSONMessageSerializerGremlinV2d0();
Cluster.Builder clusterBuilder = Cluster.build().addContactPoint(hostName)
.serializer(serializer)
.port(port).enableSsl(enableSsl)
.credentials(username, password);
cluster = clusterBuilder.create();
} catch (Exception e) {
log.error("Error in connecting to host address.", e);
}
return cluster;
}
}
And I have to define this connection component currently in order to send queries to the database:
import org.apache.tinkerpop.gremlin.driver.Client;
import org.apache.tinkerpop.gremlin.driver.Cluster;
import org.apache.tinkerpop.gremlin.driver.ResultSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class GraphDbConnection {
private final static Logger log = LoggerFactory.getLogger(GraphDbConnection.class);
@Autowired
private Cluster cluster;
public ResultSet executeQuery(String query) {
Client client = connect();
ResultSet results = client.submit(query);
closeConnection(client);
return results;
}
private Client connect() {
Client client = null;
try {
client = cluster.connect();
} catch (Exception e) {
log.error("Error in connecting to host address.", e);
}
return client;
}
private void closeConnection(Client client) {
client.close();
}
}
