[GitHub] [beam] mosche commented on a change in pull request #15916: BEAM-1857 : Add Neo4jIO (initial code drop)

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mosche commented on a change in pull request #15916:
URL: https://github.com/apache/beam/pull/15916#discussion_r745525943



##########
File path: sdks/java/io/neo4j/src/main/java/org/apache/beam/sdk/io/neo4j/Neo4jIO.java
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@@ -0,0 +1,1358 @@
+/*
+ * 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.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#read()} 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 {@link ParametersMapper} maps input values to each execution of the Cypher statement.
+ * These parameter values are stored in a {@link Map} (mapping String to Object). The map is cleared
+ * after each execution.
+ *
+ * <p>The {@link RowMapper} converts output Neo4j {@link Record} values to the output of the source.
+ *
+ * <pre>{@code
+ * pipeline.apply( Neo4jIO.<Integer, String>read()

Review comment:
       This looks great, awesome :) Though I'm unfortunately not the person capable of reviewing this in detail.
   However I noticed a few minor things.
   
   - Given `read` requires `PCollection<ParameterT>` as input one cannot naively copy the code in this example. Adding the input could help understanding and avoid confusion. E.g.
     ```Java
     pipeline
       .apply(Create.of(40, 50, 60))
       .apply( Neo4jIO.<Integer, String>read()
        ... )
     ```
   - IOs often provide `read()` and `readAll()` (e.g. have a look at JdbcIO). `readAll` typically performs a parameterized read for each element of the input `PCollection`. To be consistent I would suggest to also name `Neo4jIO.read()` accordingly as `Neo4jIO.readAll()`




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