mattcasters commented on a change in pull request #15916: URL: https://github.com/apache/beam/pull/15916#discussion_r749182053
########## File path: sdks/java/io/neo4j/src/main/java/org/apache/beam/sdk/io/neo4j/Neo4jIO.java ########## @@ -0,0 +1,1346 @@ +/* + * 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 org.apache.beam.sdk.io.neo4j; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument; + +import com.google.auto.value.AutoValue; +import java.io.Serializable; +import java.net.URI; +import java.net.URISyntaxException; +import java.time.Duration; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.TimeUnit; +import java.util.logging.Level; +import org.apache.beam.repackaged.core.org.apache.commons.lang3.StringUtils; +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.coders.Coder; +import org.apache.beam.sdk.harness.JvmInitializer; +import org.apache.beam.sdk.options.ValueProvider; +import org.apache.beam.sdk.schemas.NoSuchSchemaException; +import org.apache.beam.sdk.schemas.Schema; +import org.apache.beam.sdk.schemas.SchemaRegistry; +import org.apache.beam.sdk.transforms.DoFn; +import org.apache.beam.sdk.transforms.PTransform; +import org.apache.beam.sdk.transforms.ParDo; +import org.apache.beam.sdk.transforms.SerializableFunction; +import org.apache.beam.sdk.transforms.display.DisplayData; +import org.apache.beam.sdk.transforms.display.HasDisplayData; +import org.apache.beam.sdk.values.PCollection; +import org.apache.beam.sdk.values.PDone; +import org.apache.beam.sdk.values.TypeDescriptor; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions; +import org.checkerframework.checker.nullness.qual.Nullable; +import org.neo4j.driver.AuthTokens; +import org.neo4j.driver.Config; +import org.neo4j.driver.Driver; +import org.neo4j.driver.GraphDatabase; +import org.neo4j.driver.Logging; +import org.neo4j.driver.Record; +import org.neo4j.driver.Result; +import org.neo4j.driver.Session; +import org.neo4j.driver.SessionConfig; +import org.neo4j.driver.TransactionConfig; +import org.neo4j.driver.TransactionWork; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * This is a Beam IO to read from, and write data to, Neo4j. + * + * <p> + * + * <p> + * + * <h3>Driver configuration</h3> + * + * <p>To read from or write to Neo4j you have to provide a {@link DriverConfiguration} using<br> + * 1. {@link DriverConfiguration#create()} (which must be {@link Serializable});<br> + * 2. or {@link DriverConfiguration#create(String, String, String)} (URL, username and password). + * + * <p>If you have trouble connecting to a Neo4j Aura database please try to disable a few security + * algorithms in your JVM. This makes sure that the right one is picked to connect: + * + * <p> + * + * <pre>{@code + * Security.setProperty( + * "jdk.tls.disabledAlgorithms", + * "SSLv3, RC4, DES, MD5withRSA, DH keySize < 1024, EC keySize < 224, 3DES_EDE_CBC, anon, NULL"); + * }</pre> + * + * <p> + * + * <p> + * + * <p>To execute this code on GCP Dataflow you can create a class which extends {@link + * JvmInitializer} and implement the {@link JvmInitializer#onStartup()} method. You need to annotate + * this new class with {@link com.google.auto.service.AutoService} + * + * <pre>{@code + * @AutoService(value = JvmInitializer.class) + * }</pre> + * + * <p> + * + * <h3>Reading from Neo4j</h3> + * + * <p>{@link Neo4jIO#readAll()} source returns a bounded collection of {@code OuptutT} as a {@code + * PCollection<OutputT>}. OutputT is the type returned by the provided {@link RowMapper}. It accepts + * parameters as input in the form of {@code ParameterT} as a {@code PCollection<ParameterT>} + * + * <p>The following example reads ages to return the IDs of Person nodes. It runs a Cypher query for + * each provided age. + * + * <p>The mapping {@link SerializableFunction} maps input values to each execution of the Cypher + * statement. In the function simply return a map containing the parameters you want to set. + * + * <p>The {@link RowMapper} converts output Neo4j {@link Record} values to the output of the source. + * + * <pre>{@code + * pipeline + * .apply(Create.of(40, 50, 60)) + * .apply(Neo4jIO.<Integer, String>readAll() + * .withDriverConfiguration(Neo4jIO.DriverConfiguration.create("neo4j://localhost:7687", "neo4j", "password")) + * .withCypher("MATCH(n:Person) WHERE n.age = $age RETURN n.id") + * .withReadTransaction() + * .withCoder(StringUtf8Coder.of()) + * .withParametersFunction( age -> Collections.singletonMap( "age", age )) + * .withRowMapper( record -> return record.get(0).asString() ) + * ); + * }</pre> + * + * <h3>Writing to Neo4j</h3> + * + * <p>Neo4j sink supports writing data to a graph. It writes a {@link PCollection} to the graph by + * collecting a batch of rows after which all rows in this batch are written together to Neo4j. This + * is done using the {@link WriteUnwind} sink transform. + * + * <p>Like the source, to configure the sink, you have to provide a {@link DriverConfiguration}. + * + * <p>In the following example we'll merge a collection of {@link org.apache.beam.sdk.values.Row} + * into Person nodes. Since this is a Sink it has no output and as such no RowMapper is needed. The + * rows are being used as a container for the parameters of the Cypher statement. The used Cypher in + * question needs to be an UNWIND statement. Like in the read case, the parameters {@link + * SerializableFunction} converts parameter values to a {@link Map<String, Object>}. The difference + * here is that the resulting Map is stored in a {@link List} (containing maps) which in turn is + * stored in another Map under the name provided by the {@link + * WriteUnwind#withUnwindMapName(String)} method. All of this is handled automatically. You do need + * to provide the unwind map name so that you can reference that in the UNWIND statement. + * + * <p> + * + * <p>For example: + * + * <pre>{@code + * pipeline + * .apply(...) + * .apply(Neo4jIO.<Row>writeUnwind() + * .withDriverConfiguration(Neo4jIO.DriverConfiguration.create("neo4j://localhost:7687", "neo4j", "password")) + * .withUnwindMapName("rows") + * .withCypher("UNWIND $rows AS row MERGE(n:Person { id : row.id } ) SET n.firstName = row.first, n.lastName = row.last") + * .withParametersFunction( row -> ImmutableMap.of( + * "id", row.getString("id), + * "first", row.getString("firstName") + * "last", row.getString("lastName"))) + * ); + * }</pre> + */ +@Experimental(Experimental.Kind.SOURCE_SINK) +public class Neo4jIO { + + private static final Logger LOG = LoggerFactory.getLogger(Neo4jIO.class); + + /** + * Read all rows using a Neo4j Cypher query. + * + * @param <ParameterT> Type of the data representing query parameters. + * @param <OutputT> Type of the data to be read. + */ + public static <ParameterT, OutputT> ReadAll<ParameterT, OutputT> readAll() { + return new AutoValue_Neo4jIO_ReadAll.Builder<ParameterT, OutputT>() + .setFetchSize(ValueProvider.StaticValueProvider.of(Config.defaultConfig().fetchSize())) + .build(); + } + + /** + * Write all rows using a Neo4j Cypher UNWIND cypher statement. This sets a default batch batch + * size of 5000. + * + * @param <ParameterT> Type of the data representing query parameters. + */ + public static <ParameterT> WriteUnwind<ParameterT> writeUnwind() { + return new AutoValue_Neo4jIO_WriteUnwind.Builder<ParameterT>() + .setBatchSize(ValueProvider.StaticValueProvider.of(5000L)) + .build(); + } + + private static <ParameterT, OutputT> PCollection<OutputT> getOutputPCollection( + PCollection<ParameterT> input, DoFn<ParameterT, OutputT> writeFn, Coder<OutputT> coder) { + PCollection<OutputT> output = input.apply(ParDo.of(writeFn)).setCoder(coder); + + try { + TypeDescriptor<OutputT> typeDesc = coder.getEncodedTypeDescriptor(); + SchemaRegistry registry = input.getPipeline().getSchemaRegistry(); + Schema schema = registry.getSchema(typeDesc); + output.setSchema( + schema, + typeDesc, + registry.getToRowFunction(typeDesc), + registry.getFromRowFunction(typeDesc)); + } catch (NoSuchSchemaException e) { + // ignore + } + return output; + } + + /** + * An interface used by {@link ReadAll} for converting each row of a Neo4j {@link Result} record + * {@link Record} into an element of the resulting {@link PCollection}. + */ + @FunctionalInterface + public interface RowMapper<T> extends Serializable { + T mapRow(Record record) throws Exception; + } + + /** This describes all the information needed to create a Neo4j {@link Session}. */ + @AutoValue + public abstract static class DriverConfiguration implements Serializable { + public static DriverConfiguration create() { + return new AutoValue_Neo4jIO_DriverConfiguration.Builder().build(); + } + + public static DriverConfiguration create(String url, String username, String password) { + checkArgument(url != null, "url can not be null"); + checkArgument(username != null, "username can not be null"); + checkArgument(password != null, "password can not be null"); + return new AutoValue_Neo4jIO_DriverConfiguration.Builder() + .build() + .withUrl(url) + .withUsername(username) + .withPassword(password); + } + + abstract @Nullable ValueProvider<String> getUrl(); Review comment: Thanks for all the feedback and comments. For sure removing Nullable is an option in general. However, in this specific case the Neo4j Java driver makes a distinction between specifically encrypted connections, specifically non-encrypted connections and with encrypted not specified (e.g. null in our case). In that last case the driver figures things out automatically. In other words, the Spotless warning was correct and the earlier code was for sure in error. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
