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Subject [GitHub] ambition119 commented on a change in pull request #3379: Issue #3378: [pulsar-io] Support Pulsar to receive and send data from Apache NiFi
Date Thu, 24 Jan 2019 04:23:13 GMT
ambition119 commented on a change in pull request #3379: Issue #3378: [pulsar-io] Support Pulsar
to receive and send data from Apache NiFi 
URL: https://github.com/apache/pulsar/pull/3379#discussion_r250462500
 
 

 ##########
 File path: pulsar-io/nifi/src/main/java/org/apache/pulsar/io/nifi/NiFiSource.java
 ##########
 @@ -0,0 +1,169 @@
+/**
+ * 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.pulsar.io.nifi;
+
+import lombok.extern.slf4j.Slf4j;
+import org.apache.nifi.remote.Transaction;
+import org.apache.nifi.remote.TransferDirection;
+import org.apache.nifi.remote.client.SiteToSiteClient;
+import org.apache.nifi.remote.client.SiteToSiteClientConfig;
+import org.apache.nifi.remote.protocol.DataPacket;
+import org.apache.nifi.stream.io.StreamUtils;
+import org.apache.pulsar.functions.api.Record;
+import org.apache.pulsar.io.core.PushSource;
+import org.apache.pulsar.io.core.SourceContext;
+import org.apache.pulsar.io.core.annotations.Connector;
+import org.apache.pulsar.io.core.annotations.IOType;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+
+/**
+ * A source that pulls data from Apache NiFi using the NiFi Site-to-Site client. This source
+ * produces NiFiDataPackets which encapsulate the content and attributes of a NiFi FlowFile.
+ */
+@Connector(
+    name = "nifi",
+    type = IOType.SOURCE,
+    help = "A simple connector to move messages from Apache NiFi using the NiFi Site-to-Site
client to a Pulsar topic",
+    configClass = NiFiConfig.class)
+@Slf4j
+public class NiFiSource extends PushSource<NiFiDataPacket> {
+
+    private long waitTimeMs;
+    private volatile boolean isRunning = true;
+    private NiFiConfig niFiConfig;
+    private SiteToSiteClientConfig clientConfig;
+
+    Thread runnerThread;
+
+    @Override
+    public void open(Map<String, Object> config, SourceContext sourceContext) throws
Exception {
+        niFiConfig = NiFiConfig.load(config);
+        if (niFiConfig.getUrl() == null
+                || niFiConfig.getPortName() == null) {
+            throw new IllegalArgumentException("Required property not set.");
+        }
+
+        waitTimeMs = niFiConfig.getWaitTimeMs();
+        clientConfig = new SiteToSiteClient.Builder()
+                .url(niFiConfig.getUrl())
+                .portName(niFiConfig.getPortName())
+                .requestBatchCount(niFiConfig.getRequestBatchCount())
+                .buildConfig();
+
+        this.start();
+    }
+
+    @Override
+    public void close() throws Exception {
+        this.isRunning = false;
+        if (runnerThread != null) {
+            runnerThread.interrupt();
+            runnerThread.join();
+            runnerThread = null;
+        }
+    }
+
+    protected void start() throws Exception {
+        runnerThread = new Thread(new ReceiveRunnable());
+        runnerThread.setName("Nifi Source Thread");
+        runnerThread.start();
+    }
+
+
+    class ReceiveRunnable implements Runnable {
+
+        public ReceiveRunnable() {
+        }
+
+        @Override
+        public void run() {
+            try {
+                final SiteToSiteClient client = new SiteToSiteClient.Builder().fromConfig(clientConfig).build();
+                try {
+                    while (isRunning) {
+                        final Transaction transaction = client.createTransaction(TransferDirection.RECEIVE);
+                        DataPacket dataPacket = transaction.receive();
+                        if (dataPacket == null) {
+                            transaction.confirm();
+                            transaction.complete();
+
+                            // no data available. Wait a bit and try again
+                            try {
+                                Thread.sleep(waitTimeMs);
+                            } catch (InterruptedException e) {
+                            }
+                            continue;
+                        }
+
+                        final List<NiFiDataPacket> dataPackets = new ArrayList<>();
+                        do {
+                            // Read the data into a byte array and wrap it along with the
attributes
+                            // into a NiFiDataPacket.
+                            final InputStream inStream = dataPacket.getData();
+                            final byte[] data = new byte[(int) dataPacket.getSize()];
+                            StreamUtils.fillBuffer(inStream, data);
+
+                            final Map<String, String> attributes = dataPacket.getAttributes();
+                            final NiFiDataPacket NiFiDataPacket = new StandardNiFiDataPacket(data,
attributes);
+                            dataPackets.add(NiFiDataPacket);
+                            dataPacket = transaction.receive();
+                        } while (dataPacket != null);
 
 Review comment:
   > You should add some sort of batching here so that you don't get an OOM exception.
We are on the receiving end of a NiFi client that could be sending an unlimited stream of
data, so keeping all of these packets in memory isn't a great long term strategy.
   
   when we create SiteToSiteClient, use requestBatchCount pulling data from a NiFi instance(
the client has the ability to request a particular batch size).

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