Full Steam Ahead, R2DBC!

C5f6e8dffbb19acf405198c8fb917337?s=47 Mark Paluch
September 03, 2020

Full Steam Ahead, R2DBC!

It’s almost three years since the inception of the open standard Reactive Relational Database Connectivity specification (R2DBC). R2DBC is driven by the community. It started as a research project to explore how reactive applications running on the JVM can integrate with SQL databases using an end-to-end reactive approach. Learn in this session how R2DBC started and what you can do today. We’ll have a look at various database drivers and client projects. If you’re new to R2DBC, then this session will introduce R2DBC key concepts to you and will give you an overview of the specification.

C5f6e8dffbb19acf405198c8fb917337?s=128

Mark Paluch

September 03, 2020
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  1. Full Steam Ahead! Mark Paluch • Spring Data Project Lead,

    R2DBC Contributor • @mp911de
  2. Reactive Relational Database Connectivity

  3. Unless otherwise indicated, these slides are © 2013-2020 vmware and

    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Mark Paluch • Spring Data, R2DBC, Lettuce Redis Driver • All things non-blocking • @mp911de (Twitter, GitHub) 3
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ 4 2009 Microsoft to release .NET 4.0 2013 Reactive Manifesto Initial Akka release 2014 RxJava 1.0 2015 Reactive Streams 1.0 Project Reactor 2.0 2016 RxJava 2.0 Akka Streams 1.0 Ratpack Spring WebFlux Micronaut Today RSocket Reactive Mongo Lettuce Cassandra vert.x Lagom Apple Servicetalk Helidon RxJava 3.0 Project Reactor 3.0
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Programming Models Have Changed • Reactive applications typically stream-processing • Push-based models • Notifications, Events • Is SQL the right choice for reactive applications? • Depends on the Use-Case 5
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Reactive Programming • High-efficiency applications • Fundamentally non-blocking • No opinion on async • Key differentiators: (pull-push) back pressure, flow control 6
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Persistence • ✅ Kafka • ✅ MongoDB • ✅ Cassandra • ✅ Couchbase • ✅ Redis • ❌ Oracle, DB2, MySQL, MariaDB, Postgres, SQL Server* 7
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Persistence • ✅ Kafka • ✅ MongoDB • ✅ Cassandra • ✅ Couchbase • ✅ Redis • ❌ Oracle, DB2, MySQL, MariaDB, Postgres, SQL Server* 8
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Non-blocking SQL Persistence (1/3) • MySQL: X DevAPI (Document Store API): CompletableFuture • vert.x Postgres Driver: Callback API • jasync-sql: CompletableFuture • Common API 9
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Non-blocking SQL Persistence (2/3) • JDBC on ThreadPool • RxJava JDBC • Blocks still threads • Project Loom: Production readiness unknown • Requires proper queuing and capacity controls 10
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Non-blocking SQL Persistence (3/3) • ADBA (Asynchronous Database API) • Standard-API • Based heavily on CompletableFuture • Discontinued in favor of Project Loom 11
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ 12 Standard API for reactive programming with SQL databases on the JVM
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Project of
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Design Principles • Embrace Reactive Types and Patterns • Low barrier to entry (depends on Reactive Streams and Java 8 only) • Non-blocking, all the way to the database • De-duplicate driver efforts • Documented specification • Shrink the driver SPI • Enable multiple "humane" APIs 14
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Simple Select 15 Publisher<String> values = connectionFactory.create() .flatMapMany(conn -> conn.createStatement("SELECT value FROM test") .execute() .flatMap(result -> result.map((row, metadata) -> row.get("value", String.class))))
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2DBC 0.8 • Stable release • End-to-end reactive non-blocking database communication • Batching • BLOB/CLOB • Extensive Type Conversion • Savepoints • Transactions • Leveraging Database-specific features • ServiceLoader-based Driver discovery • Connection URLs • Categorized exceptions (Bad grammar, Data integrity violation, …) 16
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2DBC 0.9 / 1.0 • Evolution of the specification • Extended transaction spec • Improved In/Out Parameter Bindings • Investigation on stored procedures • No real demand so far • Scheduled for 2021 17
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2DBC Ecosystem • Specification document • R2DBC SPI • R2DBC Proxy • Connection Pooling • Client Implementations • Spring • Querydsl • R2DBC Migrate • Kotysa • Testcontainers • Driver Community • Google Cloud Spanner • H2 • Microsoft SQL Server • MySQL Driver (r2dbc-mysql, jasync-sql) • MariaDB • PostgreSQL • SAP Hana • Oracle (work in progress) • DB2 (work in progress) 18
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Community Projects • Specification document • R2DBC SPI • R2DBC Proxy • Connection Pooling • Client Implementations • Spring • Querydsl • R2DBC Migrate • Kotysa • Testcontainers • Driver Community • Google Cloud Spanner • H2 • Microsoft SQL Server • MySQL Driver (r2dbc-mysql, jasync-sql) • MariaDB • PostgreSQL • SAP Hana • Oracle (work in progress) • DB2 (work in progress) 19
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2DBC Clients: Work in Progress • MyBatis (#1444) • JDBI (#1454) • jOOQ (#6298) • Querydsl (#2468) • Liquibase (CORE-3419) • Flyway (#2502) • Exposed (#456) • Micronaut (#416) • Go vote for a client you want to see happen. 20
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ What R2DBC gives you • Move Thread congestion out of JVM • Achieve more with less Threads • Doesn’t change law of physics • Follow well-known SQL database interaction patterns • Database laws still apply • Obey wire protocol rules • ACID rules 21
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring ❤ R2DBC
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring and R2DBC • 2018/2019 • First steps with Spring Data R2DBC 1.0 • 2020 • Migration of core R2DBC support from Spring Data to Spring Framework 5.3 • Deprecations in Spring Data R2DBC 1.2 23
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring R2DBC • Central class: DatabaseClient • BindMarker SPI • Reactive Transaction Manager • Schema initialization support • ConnectionFactory implementations (e.g. AbstractRoutingConnectionFactory) 24
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ DatabaseClient DatabaseClient client = DatabaseClient.create(connectionFactory); Flux<Person> people = client .sql("SELECT firstname, lastname FROM person WHERE age > :age") .bind("age", 42) .filter(statement -> statement.fetchSize(20)) .map(row -> new Person(row.get("firstname", String.class), row.get("lastname", String.class))) .all(); 25
  26. Unless otherwise indicated, these slides are © 2013-2020 vmware and

    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ ConnectionFactoryInitializer @Bean ConnectionFactoryInitializer initializer(ConnectionFactory connectionFactory) { ConnectionFactoryInitializer initializer = new ConnectionFactoryInitializer(); initializer.setConnectionFactory(connectionFactory); initializer.setDatabasePopulator(new ResourceDatabasePopulator( new ClassPathResource("schema.sql"))); return initializer; } 26
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Data R2DBC • Mapped entity support through R2dbcEntityOperations • Query and Update objects • Dialect-awareness • Repository abstraction • Sorry, no mapped relations yet 27
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2dbcEntityTemplate R2dbcEntityTemplate entityTemplate = …; Flux<Person> people = entityTemplate.select(Person.class) .from("people") .matching(query(where("age").greaterThan(42)) .limit(10) .offset(20) .sort(by("firstname"))) .all(); 28
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ R2dbcEntityTemplate R2dbcEntityTemplate entityTemplate = …; Flux<Person> people = entityTemplate.select(Person.class) .from("people") .matching(query(where("age").greaterThan(42)) .limit(10) .offset(20) .sort(by("firstname"))) .all(); 29 query(where("age").greaterThan(42)) .limit(10) .offset(20) .sort(by("firstname"))
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Repositories interface PersonRepository extends ReactiveSortingRepository<Person, Integer> { Flux<Person> findByFirstnameContains(String name); Flux<Person> findFirst10By(); Flux<Person> findAllByOrderByLastname(Pageable pageable); @Modifying @Query("DELETE FROM person WHERE age = :age") Mono<Void> deleteAllByAge(int age); @Modifying @Query("DELETE FROM person") Mono<Integer> deleteAllAndReturnCount(); } 30
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Data R2DBC 1.2: New and Noteworthy • Entity Callbacks • Before/After Convert, Before/After Save • Auditing • SpEL Context Extensions • Enum value revision • Repository metrics SPI 31
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Entity Callbacks @FunctionalInterface interface BeforeConvertCallback<T> extends EntityCallback<T> { Publisher<T> onBeforeConvert(T entity, SqlIdentifier table); } 32
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Entity Callback in Action @Bean BeforeConvertCallback<Person> autogeneratedId(DatabaseClient client) { return (entity, table) -> { if (entity.getId() == null) { return client.sql("SELECT nextval('person_seq')") .map(row -> row.get(0, Integer.class)) .first() .map(entity::withId); } return Mono.just(entity); }; } 33
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    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Outlook: Spring Data R2DBC 2.0 • Closer alignment of Spring Data JDBC and Spring Data R2DBC • Evolution of Spring Data Relational 34
  35. Thank you. r2dbc.io @mp911de

  36. Unless otherwise indicated, these slides are © 2013-2020 vmware and

    licensed under a Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Resources • Website https://r2dbc.io • Twitter @r2dbc • GitHub https://github.com/r2dbc • Mailing List https://groups.google.com/forum/ #!forum/r2dbc • Monthly Call 1st Friday of Month 0630 PT/0930 ET/1530 CET 36