[KAFKA] Adding new client code

[dmaap/kafka11aaf.git] / kafkaClient / src / main / java / org / onap / dmaap / kafka / OnapKafkaConsumer.java

diff --git a/kafkaClient/src/main/java/org/onap/dmaap/kafka/OnapKafkaConsumer.java b/kafkaClient/src/main/java/org/onap/dmaap/kafka/OnapKafkaConsumer.java
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+++ b/kafkaClient/src/main/java/org/onap/dmaap/kafka/OnapKafkaConsumer.java
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+/*-
+ * ============LICENSE_START=======================================================
+ * dmaap-kafka-client
+ * ================================================================================
+ * Copyright (C) 2023 Nordix Foundation. All rights reserved.
+ * ================================================================================
+ * Licensed 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.dmaap.kafka;
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+import java.util.UUID;
+import org.apache.kafka.clients.CommonClientConfigs;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.KafkaException;
+import org.apache.kafka.common.config.SaslConfigs;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Utility class that provides a KafkaConsumer to communicate with a kafka cluster
+ */
+public class OnapKafkaConsumer {
+
+    private final Logger log = LoggerFactory.getLogger(OnapKafkaConsumer.class);
+    private final KafkaConsumer<String, String> consumer;
+    private final int pollTimeout;
+    private final List<String> consumerTopics;
+
+    /**
+     *
+     * @param configuration The config provided to the client
+     */
+    public OnapKafkaConsumer(IKafkaConfig configuration) {
+        consumerTopics = configuration.getConsumerTopics();
+        log.debug("Instantiating kafka consumer for topics {}", consumerTopics);
+
+        Properties props = new Properties();
+        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
+        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,  "org.apache.kafka.common.serialization.StringDeserializer");
+        props.put(ConsumerConfig.CLIENT_ID_CONFIG, configuration.getConsumerID() + "-consumer-" + UUID.randomUUID());
+        props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, configuration.getKafkaSecurityProtocolConfig());
+        props.put(CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG, configuration.getKafkaBootstrapServers());
+        props.put(SaslConfigs.SASL_JAAS_CONFIG, configuration.getKafkaSaslJaasConfig());
+        props.put(SaslConfigs.SASL_MECHANISM, configuration.getKafkaSaslMechanism());
+        props.put(ConsumerConfig.GROUP_ID_CONFIG, configuration.getConsumerGroup());
+        props.put(ConsumerConfig.ALLOW_AUTO_CREATE_TOPICS_CONFIG, false);
+        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
+        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);
+
+        consumer = new KafkaConsumer<>(props);
+
+        pollTimeout = configuration.getPollingTimeout();
+    }
+
+    /**
+     *  Poll specified topic for existing messages
+     *
+     * @return List of messages from a specific topic
+     */
+    List<String> poll(String topicName) throws KafkaException {
+        List<String> msgs = new ArrayList<>();
+        log.debug("Polling records for topic {}", topicName);
+        ConsumerRecords<String, String> consumerRecordsForSpecificTopic = consumer.poll(Duration.ofSeconds(pollTimeout));
+        for(ConsumerRecord<String, String> rec : consumerRecordsForSpecificTopic){
+            if (rec.topic().equals(topicName)) {
+                msgs.add(rec.value());
+            }
+        }
+        return msgs;
+    }
+
+    /**
+     *  Poll topics for existing messages
+     *
+     * @return List of messages from all subscribed topic
+     */
+    List<String> poll() throws KafkaException {
+        List<String> msgs = new ArrayList<>();
+        log.debug("Polling all records");
+        ConsumerRecords<String, String> consumerRecords = consumer.poll(Duration.ofSeconds(pollTimeout));
+        for(ConsumerRecord<String, String> rec : consumerRecords){
+            msgs.add(rec.value());
+        }
+        return msgs;
+    }
+
+    public void subscribeConsumerToTopics() {
+        try {
+            consumer.subscribe(consumerTopics);
+        }
+        catch (KafkaException e) {
+            log.error("Failed to subscribe to given topic(s) {} : {}", consumerTopics, e.getMessage());
+            throw e;
+        }
+    }
+}
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