Amazon DynamoDB
開発者ガイド (API バージョン 2012-08-10)

DynamoDB ストリーム の低レベル API: Java の例

注記

このページのコードはすべてを網羅していないため、DynamoDB ストリームを使用するすべてのシナリオに対応しているわけではありません。DynamoDB からストリームレコードを使用する推奨の方法は、「DynamoDB ストリーム Kinesis Adapter を使用したストリームレコードの処理」で説明しているように、Kinesis Client Library (KCL) を使用し、Kinesis Adapter を介して行うことです。

このセクションには、動作中の DynamoDB ストリーム を示す Java プログラムが含まれています。 このプログラムでは、次のような処理を実行します。

  1. ストリームが有効になった DynamoDB テーブルを作成します。

  2. このテーブルのストリーム設定を記述します。

  3. テーブル内のデータを変更します。

  4. ストリーム内のシャードを記述します。

  5. シャードからストリームレコードを読み込みます。

  6. クリーンアップ.

プログラムを実行すると、以下のような出力が表示されます。

Issuing CreateTable request for TestTableForStreams Waiting for TestTableForStreams to be created... Current stream ARN for TestTableForStreams: arn:aws:dynamodb:us-east-2:123456789012:table/TestTableForStreams/stream/2018-03-20T16:49:55.208 Stream enabled: true Update view type: NEW_AND_OLD_IMAGES Performing write activities on TestTableForStreams Processing item 1 of 100 Processing item 2 of 100 Processing item 3 of 100 ... Processing item 100 of 100 Shard: {ShardId: shardId-1234567890-...,SequenceNumberRange: {StartingSequenceNumber: 01234567890...,},} Shard iterator: EjYFEkX2a26eVTWe... ApproximateCreationDateTime: Tue Mar 20 09:50:00 PDT 2018,Keys: {Id={N: 1,}},NewImage: {Message={S: New item!,}, Id={N: 1,}},SequenceNumber: 100000000003218256368,SizeBytes: 24,StreamViewType: NEW_AND_OLD_IMAGES} {ApproximateCreationDateTime: Tue Mar 20 09:50:00 PDT 2018,Keys: {Id={N: 1,}},NewImage: {Message={S: This item has changed,}, Id={N: 1,}},OldImage: {Message={S: New item!,}, Id={N: 1,}},SequenceNumber: 200000000003218256412,SizeBytes: 56,StreamViewType: NEW_AND_OLD_IMAGES} {ApproximateCreationDateTime: Tue Mar 20 09:50:00 PDT 2018,Keys: {Id={N: 1,}},OldImage: {Message={S: This item has changed,}, Id={N: 1,}},SequenceNumber: 300000000003218256413,SizeBytes: 36,StreamViewType: NEW_AND_OLD_IMAGES} ... Deleting the table... Demo complete

// Copyright 2012-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved. // Licensed under the Apache License, Version 2.0. package com.amazon.codesamples; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; import com.amazonaws.AmazonClientException; import com.amazonaws.auth.DefaultAWSCredentialsProviderChain; import com.amazonaws.regions.Regions; import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBStreams; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBStreamsClientBuilder; import com.amazonaws.services.dynamodbv2.model.AttributeAction; import com.amazonaws.services.dynamodbv2.model.AttributeDefinition; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import com.amazonaws.services.dynamodbv2.model.AttributeValueUpdate; import com.amazonaws.services.dynamodbv2.model.CreateTableRequest; import com.amazonaws.services.dynamodbv2.model.DescribeStreamRequest; import com.amazonaws.services.dynamodbv2.model.DescribeStreamResult; import com.amazonaws.services.dynamodbv2.model.DescribeTableResult; import com.amazonaws.services.dynamodbv2.model.GetRecordsRequest; import com.amazonaws.services.dynamodbv2.model.GetRecordsResult; import com.amazonaws.services.dynamodbv2.model.GetShardIteratorRequest; import com.amazonaws.services.dynamodbv2.model.GetShardIteratorResult; import com.amazonaws.services.dynamodbv2.model.KeySchemaElement; import com.amazonaws.services.dynamodbv2.model.KeyType; import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput; import com.amazonaws.services.dynamodbv2.model.Record; import com.amazonaws.services.dynamodbv2.model.Shard; import com.amazonaws.services.dynamodbv2.model.ShardIteratorType; import com.amazonaws.services.dynamodbv2.model.StreamSpecification; import com.amazonaws.services.dynamodbv2.model.StreamViewType; import com.amazonaws.services.dynamodbv2.util.TableUtils; public class StreamsLowLevelDemo { public static void main(String args[]) throws InterruptedException { AmazonDynamoDB dynamoDBClient = AmazonDynamoDBClientBuilder .standard() .withRegion(Regions.US_EAST_2) .withCredentials(new DefaultAWSCredentialsProviderChain()) .build(); AmazonDynamoDBStreams streamsClient = AmazonDynamoDBStreamsClientBuilder .standard() .withRegion(Regions.US_EAST_2) .withCredentials(new DefaultAWSCredentialsProviderChain()) .build(); // Create a table, with a stream enabled String tableName = "TestTableForStreams"; ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<>( Arrays.asList(new AttributeDefinition() .withAttributeName("Id") .withAttributeType("N"))); ArrayList<KeySchemaElement> keySchema = new ArrayList<>( Arrays.asList(new KeySchemaElement() .withAttributeName("Id") .withKeyType(KeyType.HASH))); // Partition key StreamSpecification streamSpecification = new StreamSpecification() .withStreamEnabled(true) .withStreamViewType(StreamViewType.NEW_AND_OLD_IMAGES); CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName) .withKeySchema(keySchema).withAttributeDefinitions(attributeDefinitions) .withProvisionedThroughput(new ProvisionedThroughput() .withReadCapacityUnits(10L) .withWriteCapacityUnits(10L)) .withStreamSpecification(streamSpecification); System.out.println("Issuing CreateTable request for " + tableName); dynamoDBClient.createTable(createTableRequest); System.out.println("Waiting for " + tableName + " to be created..."); try { TableUtils.waitUntilActive(dynamoDBClient, tableName); } catch (AmazonClientException e) { e.printStackTrace(); } // Print the stream settings for the table DescribeTableResult describeTableResult = dynamoDBClient.describeTable(tableName); String streamArn = describeTableResult.getTable().getLatestStreamArn(); System.out.println("Current stream ARN for " + tableName + ": " + describeTableResult.getTable().getLatestStreamArn()); StreamSpecification streamSpec = describeTableResult.getTable().getStreamSpecification(); System.out.println("Stream enabled: " + streamSpec.getStreamEnabled()); System.out.println("Update view type: " + streamSpec.getStreamViewType()); System.out.println(); // Generate write activity in the table System.out.println("Performing write activities on " + tableName); int maxItemCount = 100; for (Integer i = 1; i <= maxItemCount; i++) { System.out.println("Processing item " + i + " of " + maxItemCount); // Write a new item Map<String, AttributeValue> item = new HashMap<>(); item.put("Id", new AttributeValue().withN(i.toString())); item.put("Message", new AttributeValue().withS("New item!")); dynamoDBClient.putItem(tableName, item); // Update the item Map<String, AttributeValue> key = new HashMap<>(); key.put("Id", new AttributeValue().withN(i.toString())); Map<String, AttributeValueUpdate> attributeUpdates = new HashMap<>(); attributeUpdates.put("Message", new AttributeValueUpdate() .withAction(AttributeAction.PUT) .withValue(new AttributeValue() .withS("This item has changed"))); dynamoDBClient.updateItem(tableName, key, attributeUpdates); // Delete the item dynamoDBClient.deleteItem(tableName, key); } // Get all the shard IDs from the stream. Note that DescribeStream returns // the shard IDs one page at a time. String lastEvaluatedShardId = null; do { DescribeStreamResult describeStreamResult = streamsClient.describeStream( new DescribeStreamRequest() .withStreamArn(streamArn) .withExclusiveStartShardId(lastEvaluatedShardId)); List<Shard> shards = describeStreamResult.getStreamDescription().getShards(); // Process each shard on this page for (Shard shard : shards) { String shardId = shard.getShardId(); System.out.println("Shard: " + shard); // Get an iterator for the current shard GetShardIteratorRequest getShardIteratorRequest = new GetShardIteratorRequest() .withStreamArn(streamArn) .withShardId(shardId) .withShardIteratorType(ShardIteratorType.TRIM_HORIZON); GetShardIteratorResult getShardIteratorResult = streamsClient.getShardIterator(getShardIteratorRequest); String currentShardIter = getShardIteratorResult.getShardIterator(); // Shard iterator is not null until the Shard is sealed (marked as READ_ONLY). // To prevent running the loop until the Shard is sealed, which will be on average // 4 hours, we process only the items that were written into DynamoDB and then exit. int processedRecordCount = 0; while (currentShardIter != null && processedRecordCount < maxItemCount) { System.out.println(" Shard iterator: " + currentShardIter.substring(380)); // Use the shard iterator to read the stream records GetRecordsResult getRecordsResult = streamsClient.getRecords(new GetRecordsRequest() .withShardIterator(currentShardIter)); List<Record> records = getRecordsResult.getRecords(); for (Record record : records) { System.out.println(" " + record.getDynamodb()); } processedRecordCount += records.size(); currentShardIter = getRecordsResult.getNextShardIterator(); } } // If LastEvaluatedShardId is set, then there is // at least one more page of shard IDs to retrieve lastEvaluatedShardId = describeStreamResult.getStreamDescription().getLastEvaluatedShardId(); } while (lastEvaluatedShardId != null); // Delete the table System.out.println("Deleting the table..."); dynamoDBClient.deleteTable(tableName); System.out.println("Demo complete"); } }