| /* |
| * 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 samza.examples.cookbook; |
| |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.ImmutableMap; |
| |
| import java.io.Serializable; |
| import java.net.URL; |
| import java.time.Duration; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.concurrent.CompletableFuture; |
| import org.apache.samza.SamzaException; |
| import org.apache.samza.application.StreamApplication; |
| import org.apache.samza.application.descriptors.StreamApplicationDescriptor; |
| import org.apache.samza.operators.KV; |
| import org.apache.samza.operators.MessageStream; |
| import org.apache.samza.operators.OutputStream; |
| import org.apache.samza.operators.functions.StreamTableJoinFunction; |
| import org.apache.samza.serializers.JsonSerdeV2; |
| import org.apache.samza.serializers.StringSerde; |
| import org.apache.samza.system.kafka.descriptors.KafkaInputDescriptor; |
| import org.apache.samza.system.kafka.descriptors.KafkaOutputDescriptor; |
| import org.apache.samza.system.kafka.descriptors.KafkaSystemDescriptor; |
| import org.apache.samza.table.Table; |
| import org.apache.samza.table.descriptors.CachingTableDescriptor; |
| import org.apache.samza.table.remote.BaseTableFunction; |
| import org.apache.samza.table.remote.TableReadFunction; |
| import org.apache.samza.table.descriptors.RemoteTableDescriptor; |
| import org.apache.samza.util.ExponentialSleepStrategy; |
| import org.apache.samza.util.HttpUtil; |
| import org.codehaus.jackson.JsonFactory; |
| import org.codehaus.jackson.JsonParser; |
| import org.codehaus.jackson.JsonToken; |
| import org.codehaus.jackson.annotate.JsonProperty; |
| |
| /** |
| * In this example, we join a stream of stock symbols with a remote table backed by a RESTful service, |
| * which delivers latest stock quotes. The join results contain stock symbol and latest price, and are |
| * delivered to an output stream. |
| * |
| * A rate limit of 10 requests/second is set of the entire job, internally Samza uses an embedded |
| * rate limiter, which evenly distributes the total rate limit among tasks. |
| * |
| * A caching table is used over the remote table with a read TTL of 5 seconds, therefore one would |
| * receive the same quote with this time span. |
| * |
| * <p> Concepts covered: remote table, rate limiter, caching table, stream to table joins. |
| * |
| * To run the below example: |
| * |
| * <ol> |
| * <li> |
| * Create Kafka topics "stock-symbol-input", "stock-price-output" are created <br/> |
| * ./deploy/kafka/bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic stock-symbol-input --partitions 2 --replication-factor 1 |
| * ./deploy/kafka/bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic stock-price-output --partitions 2 --replication-factor 1 |
| * </li> |
| * <li> |
| * Run the application using the run-app.sh script <br/> |
| * ./deploy/samza/bin/run-app.sh --config-factory=org.apache.samza.config.factories.PropertiesConfigFactory --config-path=file://$PWD/deploy/samza/config/remote-table-join-example.properties |
| * </li> |
| * <li> |
| * Consume messages from the output topic <br/> |
| * ./deploy/kafka/bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic stock-price-output |
| * </li> |
| * <li> |
| * Produce some messages to the input topic <br/> |
| * ./deploy/kafka/bin/kafka-console-producer.sh --topic stock-symbol-input --broker-list localhost:9092 |
| * |
| * After the console producer is started, type |
| * MSFT |
| * |
| * You should see messages like below from the console consumer window |
| * {"symbol":"MSFT","close":107.64} |
| * |
| * Note: you will need a free API key for symbols other than MSFT, see below for more information. |
| * </li> |
| * </ol> |
| * |
| */ |
| public class RemoteTableJoinExample implements StreamApplication { |
| private static final String KAFKA_SYSTEM_NAME = "kafka"; |
| private static final List<String> KAFKA_CONSUMER_ZK_CONNECT = ImmutableList.of("localhost:2181"); |
| private static final List<String> KAFKA_PRODUCER_BOOTSTRAP_SERVERS = ImmutableList.of("localhost:9092"); |
| private static final Map<String, String> KAFKA_DEFAULT_STREAM_CONFIGS = ImmutableMap.of("replication.factor", "1"); |
| |
| /** |
| * Default API key "demo" only works for symbol "MSFT"; however you can get an |
| * API key for free at https://www.alphavantage.co/, which will work for other symbols. |
| */ |
| private static final String API_KEY = "demo"; |
| |
| private static final String URL_TEMPLATE = |
| "https://www.alphavantage.co/query?function=TIME_SERIES_DAILY&symbol=%s&apikey=" + API_KEY; |
| |
| private static final String INPUT_STREAM_ID = "stock-symbol-input"; |
| private static final String OUTPUT_STREAM_ID = "stock-price-output"; |
| |
| @Override |
| public void describe(StreamApplicationDescriptor appDescriptor) { |
| KafkaSystemDescriptor kafkaSystemDescriptor = new KafkaSystemDescriptor(KAFKA_SYSTEM_NAME) |
| .withConsumerZkConnect(KAFKA_CONSUMER_ZK_CONNECT) |
| .withProducerBootstrapServers(KAFKA_PRODUCER_BOOTSTRAP_SERVERS) |
| .withDefaultStreamConfigs(KAFKA_DEFAULT_STREAM_CONFIGS); |
| |
| KafkaInputDescriptor<String> stockSymbolInputDescriptor = |
| kafkaSystemDescriptor.getInputDescriptor(INPUT_STREAM_ID, new StringSerde()); |
| KafkaOutputDescriptor<StockPrice> stockPriceOutputDescriptor = |
| kafkaSystemDescriptor.getOutputDescriptor(OUTPUT_STREAM_ID, new JsonSerdeV2<>(StockPrice.class)); |
| appDescriptor.withDefaultSystem(kafkaSystemDescriptor); |
| MessageStream<String> stockSymbolStream = appDescriptor.getInputStream(stockSymbolInputDescriptor); |
| OutputStream<StockPrice> stockPriceStream = appDescriptor.getOutputStream(stockPriceOutputDescriptor); |
| |
| RemoteTableDescriptor<String, Double> remoteTableDescriptor = |
| new RemoteTableDescriptor("remote-table") |
| .withReadRateLimit(10) |
| .withReadFunction(new StockPriceReadFunction()); |
| CachingTableDescriptor<String, Double> cachedRemoteTableDescriptor = |
| new CachingTableDescriptor<>("cached-remote-table", remoteTableDescriptor) |
| .withReadTtl(Duration.ofSeconds(5)); |
| Table<KV<String, Double>> cachedRemoteTable = appDescriptor.getTable(cachedRemoteTableDescriptor); |
| |
| stockSymbolStream |
| .map(symbol -> new KV<String, Void>(symbol, null)) |
| .join(cachedRemoteTable, new JoinFn()) |
| .sendTo(stockPriceStream); |
| |
| } |
| |
| static class JoinFn implements StreamTableJoinFunction<String, KV<String, Void>, KV<String, Double>, StockPrice> { |
| @Override |
| public StockPrice apply(KV<String, Void> message, KV<String, Double> record) { |
| return record == null ? null : new StockPrice(message.getKey(), record.getValue()); |
| } |
| @Override |
| public String getMessageKey(KV<String, Void> message) { |
| return message.getKey(); |
| } |
| @Override |
| public String getRecordKey(KV<String, Double> record) { |
| return record.getKey(); |
| } |
| } |
| |
| static class StockPriceReadFunction extends BaseTableFunction |
| implements TableReadFunction<String, Double> { |
| @Override |
| public CompletableFuture<Double> getAsync(String symbol) { |
| return CompletableFuture.supplyAsync(() -> { |
| try { |
| URL url = new URL(String.format(URL_TEMPLATE, symbol)); |
| String response = HttpUtil.read(url, 5000, new ExponentialSleepStrategy()); |
| JsonParser parser = new JsonFactory().createJsonParser(response); |
| while (!parser.isClosed()) { |
| if (JsonToken.FIELD_NAME.equals(parser.nextToken()) && "4. close".equalsIgnoreCase(parser.getCurrentName())) { |
| return Double.valueOf(parser.nextTextValue()); |
| } |
| } |
| return -1d; |
| } catch (Exception ex) { |
| throw new SamzaException(ex); |
| } |
| }); |
| } |
| |
| @Override |
| public boolean isRetriable(Throwable throwable) { |
| return false; |
| } |
| } |
| |
| public static class StockPrice implements Serializable { |
| |
| public final String symbol; |
| public final Double close; |
| |
| public StockPrice( |
| @JsonProperty("symbol") String symbol, |
| @JsonProperty("close") Double close) { |
| this.symbol = symbol; |
| this.close = close; |
| } |
| } |
| |
| } |