Change Data Streaming Use Cases With Apache Kafka and Debezium Java Day Istanbul 2020 Gunnar Morling Software Engineer @gunnarmorling

The Issue with Dual Writes What's the problem? Change data capture to the rescue! CDC Use Cases & Patterns Replication Audit Logs Microservices Practical Matters Deployment Topologies Running on Kubernetes Single Message Transforms 1 2 3

Gunnar Morling Open source software engineer at Red Hat Debezium Hibernate Quarkus Spec Lead for Bean Validation 2.0 Other projects: Layrry, Deptective, MapStruct Java Champion @gunnarmorling #Debezium

A Common Problem Updating Multiple Resources Database Order Service @gunnarmorling #Debezium

A Common Problem Updating Multiple Resources Cache Database Order Service @gunnarmorling #Debezium

A Common Problem Updating Multiple Resources Cache Database Order Service Search Index @gunnarmorling #Debezium

A Common Problem Updating Multiple Resources Order Service Cache Database Search Index “ Friends Don't Let Friends Do Dual Writes @gunnarmorling #Debezium

A Better Solution Streaming Change Events From the Database Order Service @gunnarmorling #Debezium

A Better Solution Streaming Change Events From the Database Order Service C C U C U U D C C - Create U - Update D - Delete Change Data Capture @gunnarmorling #Debezium

A Better Solution Streaming Change Events From the Database Order Service C C U C U U D C C - Create U - Update D - Delete Change Data Capture @gunnarmorling #Debezium

Change Data Capture With Debezium

Debezium Change Data Capture Platform CDC for multiple databases Based on transaction logs Snapshotting, Filtering etc. Fully open-source, very active community Via Apache Kafka or embedded Many production deployments (e.g. WePay, Shopify, Convoy, JW Player, Usabilla etc.) @gunnarmorling #Debezium

Debezium Connectors MySQL Postgres MongoDB SQL Server Incubating: Db2 Cassandra Oracle (Incubating, based on XStream) @gunnarmorling #Debezium

Meme idea: Robin Moffatt

Log- vs. Query-Based CDC Query-Based Log-Based All data changes are captured - + No polling delay or overhead - + Transparent to writing applications and models - + Can capture deletes and old record state - + Installation/Configuration + - @gunnarmorling #Debezium

{ "before": null, "after": { "id": 1004, "first_name": "Anne", "last_name": "Kretchmar", "email": "[email protected]" }, "source": { "name": "dbserver1", "server_id": 0, "ts_sec": 0, "file": "mysql-bin.000003", "pos": 154, "row": 0, "snapshot": true, "db": "inventory", "table": "customers" }, "op": "c", "ts_ms": 1486500577691 } Change Event Structure Key: Primary key of table Value: Describing the change event Old row state New row state Metadata Serialization formats: JSON Avro Using a schema registry @gunnarmorling #Debezium

The Issue with Dual Writes What's the problem? Change data capture to the rescue! 1 2 3 CDC Use Cases & Patterns Replication Audit Logs Microservices Practical Matters Deployment Topologies Running on Kubernetes Single Message Transforms

CDC – "Liberation for Your Data" @gunnarmorling #Debezium

Postgres MySQL Apache Kafka Data Replication Zero-Code Streaming Pipelines @gunnarmorling #Debezium

Postgres MySQL Apache Kafka Kafka Connect Kafka Connect Data Replication Zero-Code Streaming Pipelines @gunnarmorling #Debezium

Postgres MySQL Apache Kafka Kafka Connect Kafka Connect DBZ PG DBZ MySQL Data Replication Zero-Code Streaming Pipelines @gunnarmorling #Debezium

Postgres MySQL Kafka Connect Kafka Connect Apache Kafka DBZ PG DBZ MySQL Elasticsearch ES Connector Data Replication Zero-Code Streaming Pipelines @gunnarmorling #Debezium

Postgres MySQL Kafka Connect Kafka Connect Apache Kafka DBZ PG DBZ MySQL Elasticsearch ES Connector JDBC Connector ES Connector Data Warehouse Data Replication Zero-Code Streaming Pipelines @gunnarmorling #Debezium

Postgres MySQL Kafka Connect Kafka Connect Apache Kafka DBZ PG DBZ MySQL Elasticsearch ES Connector JDBC Connector ES Connector ISPN Connector Infinispan Data Replication Zero-Code Streaming Pipelines Data Warehouse @gunnarmorling #Debezium

Postgres MySQL Kafka Connect Kafka Connect Apache Kafka DBZ PG DBZ MySQL Elasticsearch ES Connector JDBC Connector ES Connector ISPN Connector Infinispan Data Replication Zero-Code Streaming Pipelines Data Warehouse @gunnarmorling #Debezium

Data Replication Low-Latency Streaming Pipelines https://medium.com/convoy-tech/ @gunnarmorling #Debezium

Auditing Source DB Kafka Connect Apache Kafka DBZ Customer Events CRM Service @gunnarmorling #Debezium

Auditing Source DB Kafka Connect Apache Kafka DBZ Customer Events CRM Service Id User Use Case tx-1 Bob Create Customer tx-2 Sarah Delete Customer tx-3 Rebecca Update Customer "Transactions" table @gunnarmorling #Debezium

Auditing Source DB Kafka Connect Apache Kafka DBZ Customer Events Transactions CRM Service Id User Use Case tx-1 Bob Create Customer tx-2 Sarah Delete Customer tx-3 Rebecca Update Customer "Transactions" table @gunnarmorling #Debezium

Auditing Source DB Kafka Connect Apache Kafka DBZ Customer Events Transactions CRM Service Kafka Streams Id User Use Case tx-1 Bob Create Customer tx-2 Sarah Delete Customer tx-3 Rebecca Update Customer "Transactions" table @gunnarmorling #Debezium

Auditing Source DB Kafka Connect Apache Kafka DBZ Customer Events Transactions CRM Service Kafka Streams Id User Use Case tx-1 Bob Create Customer tx-2 Sarah Delete Customer tx-3 Rebecca Update Customer "Transactions" table Enriched Customer Events bit.ly/debezium-auditlogs @gunnarmorling #Debezium

{ "id": "tx-3" } { "before": { "id": 1004, "last_name": "Kretchmar", "email": "[email protected]" }, "after": { "id": 1004, "last_name": "Kretchmar", "email": "[email protected]" }, "source": { "name": "dbserver1", "table": "customers", "txId": "tx-3" }, "op": "u", "ts_ms": 1486500577691 } Transactions Customers { "before": null, "after": { "id": "tx-3", "user": "Rebecca", "use_case": "Update customer" }, "source": { "name": "dbserver1", "table": "transactions", "txId": "tx-3" }, "op": "c", "ts_ms": 1486500577691 } @gunnarmorling #Debezium

{ "before": { "id": 1004, "last_name": "Kretchmar", "email": "[email protected]" }, "after": { "id": 1004, "last_name": "Kretchmar", "email": "[email protected]" }, "source": { "name": "dbserver1", "table": "customers", "txId": "tx-3", "user": "Rebecca", "use_case": "Update customer" }, "op": "u", "ts_ms": 1486500577691 } Enriched Customers Auditing @gunnarmorling #Debezium

@Override public KeyValue transform(JsonObject key, JsonObject value) { boolean enrichedAllBufferedEvents = enrichAndEmitBufferedEvents(); if (!enrichedAllBufferedEvents) { bufferChangeEvent(key, value); return null; } KeyValue enriched = enrichWithTxMetaData(key, value); if (enriched == null) { bufferChangeEvent(key, value); } return enriched; } Auditing Non-trivial join implementation no ordering across topics need to buffer change events until TX data available bit.ly/debezium-auditlogs @gunnarmorling #Debezium

Microservice CDC Patterns

Order Item Stock App Local DB Local DB Local DB App App Item Changes Stock Changes Microservice Architectures Data Synchronization Propagate data between different services without coupling Each service keeps optimised views locally @gunnarmorling #Debezium

Source DB Kafka Connect Apache Kafka DBZ Order Events Credit Worthiness Check Events Outbox Pattern Separate Events Table Order Service Shipment Service Customer Service Orders Outbox @gunnarmorling #Debezium

Source DB Kafka Connect Apache Kafka DBZ Order Events Credit Worthiness Check Events Outbox Pattern Separate Events Table Order Service Shipment Service Customer Service Id AggregateType AggregateId Type Payload ec6e Order 123 OrderCreated { "id" : 123, ... } 8af8 Order 456 OrderDetailCanceled { "id" : 456, ... } 890b Customer 789 InvoiceCreated { "id" : 789, ... } "Outbox" table bit.ly/debezium-outbox-pattern Orders Outbox @gunnarmorling #Debezium

Strangler Pattern Migrating from Monoliths to Microservices https://martinfowler.com/bliki/StranglerFigApplication.html @gunnarmorling #Debezium

Customer Strangler Pattern @gunnarmorling #Debezium

Router CDC Customer Customer' Reads/ Writes Reads Strangler Pattern Transformation @gunnarmorling #Debezium

Router CDC Customer Reads/ Writes Reads/ Writes CDC Strangler Pattern @gunnarmorling #Debezium

The Issue with Dual Writes What's the problem? Change data capture to the rescue! 1 3 2 CDC Use Cases & Patterns Replication Audit Logs Microservices Practical Matters Deployment Topologies Running on Kubernetes Single Message Transforms

@gunnarmorling Deployment Topologies Basic Set-Up CDC #Debezium

Deployment Topologies Database High Availability @gunnarmorling CDC #Debezium

Deployment Topologies Database High Availability @gunnarmorling CDC #Debezium

Deployment Topologies Automatic Fail-over @gunnarmorling HA Proxy CDC #Debezium

Deployment Topologies Automatic Fail-over @gunnarmorling HA Proxy CDC #Debezium

Deployment Topologies Can't Change Binlog Mode? @gunnarmorling CDC Primary Secondary #Debezium

Deployment Topologies High Availability for Connectors @gunnarmorling CDC Deduplicator CDC #Debezium

apiVersion: "kafka.strimzi.io/v1alpha1" kind: "KafkaConnector" metadata: name: "inventory-connector" labels: connect-cluster: my-connect-cluster spec: class: i.d.c.p.PostgresConnector tasksMax: 1 config: database.hostname: "postgres", database.port: "5432", database.user: "bob", database.password: "secret", database.dbname : "prod", database.server.name: "dbserver1", schema.whitelist: "inventory" Running on Kubernetes Deployment via Operators YAML-based custom resource definitions for Kafka/Connect clusters, topics etc. Operator applies configuration Advantages Automated deployment and scaling Simplified upgrading Portability across clouds @gunnarmorling #Debezium

Sneak Peek - UI Proof-of-Concept @gunnarmorling #Debezium

@gunnarmorling Sneak Peek - UI Proof-of-Concept https://github.com/debezium/debezium-ui-poc/ #Debezium

Single Message Transformations The Swiss Army Knife of Kafka Connect Format conversions Time/date fields Extract new row state Aggregate sharded tables to single topic Keep compatibility with existing consumers Coming with Debezium: Router, "Flattener" @gunnarmorling © Emilian Robert Vicol https://flic.kr/p/c8s6Y3 #Debezium

Single Message Transformations Externalizing Large Column Values @gunnarmorling DBZ Amazon S3 #Debezium

Single Message Transformations Externalizing Large Column Values @gunnarmorling DBZ Amazon S3 { "before": { ... }, "after": { "id": 1004, "last_name": "Kretchmar", "email": "[email protected]", "image": "imgs--after" }, ... } #Debezium

Takeaways Change Data Capture – Liberation for your data! Enabling use cases such as replication, streaming queries, maintaining CQRS read models etc. Microservices: outbox and strangler patterns Debezium: open-source CDC for a growing number of databases @gunnarmorling #Debezium

Takeaways Change Data Capture – Liberation for your data! Enabling use cases such as replication, streaming queries, maintaining CQRS read models etc. Microservices: outbox and strangler patterns Debezium: open-source CDC for a growing number of databases @gunnarmorling “ Friends Don't Let Friends Do Dual-Writes #Debezium

Resources Website Source code: Latest news: @debezium debezium.io debezium.io/documentation/online-resources debezium.io/blog https://github.com/debezium/ @gunnarmorling #Debezium

[email protected] @gunnarmorling Q&A

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Outlook: View Materialization Awareness of Transaction Boundaries Topic with BEGIN/END markers Enable consumers to buffer all events of one transaction { "transactionId" : "tx-123", "eventType" : "begin transaction", "ts_ms": 1486500577125 } { "transactionId" : "tx-123", "ts_ms": 1486500577691, "eventType" : "end transaction", "eventCount" : [ { "name" : "dbserver1.inventory.Order", "count" : 1 }, { "name" : "dbserver1.inventory.OrderLine", "count" : 5 } ] } BEGIN END @gunnarmorling