Reactive Backend Applications with Spring Boot, Kotlin and Coroutines (Part 1)

• BlockHound

  6 1,297 7.0 Java

  Java agent to detect blocking calls from non-blocking threads.

  

There is a great tool called Blockhound we can use to detect if/when we have a blocking call in our application. This way, we can ensure that we don't break the non-blocking nature of our application by mistake while developing new features. Setting it up is fairly straightforward.

• reactive-kotlin-weather-api

  1 1 10.0 Kotlin
  

You can find the source code of this application at github.com/iodigital-com/reactive-kotlin-weather-api.

• WorkOS

  workos.com sponsored

  The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

  

• Reactive Streams

  16 4,746 1.9 Java

  Reactive Streams Specification for the JVM

  

Reactive programming is a paradigm that focuses on non-blocking and asynchronous processing of tasks. One set of specifications/abstractions for reactive programming on JVM is called Reactive Streams. Project Reactor is a message-driven, type-safe and functional implementation of Reactive Streams, and it is used by Spring (via spring-webflux module) to enable reactive web applications. Reactive streams model the data processing as a stream with one end producing the values and one end consuming them.

• initializr

  258 3,344 8.9 Java

  A quickstart generator for Spring projects

  

You can use start.spring.io to generate a project using Java 17, Gradle, Spring Web, Spring Data JPA, and H2 Database. Here's what the build file of our project should look like:

• r2dbc-postgresql

  4 986 7.5 Java

  Postgresql R2DBC Driver

  

Now that we have an application, let's turn it into a reactive application. For this, we will replace Spring Web dependency with Spring WebFlux, Spring Data JPA with Spring Data R2DBC. We will also add R2DBC dependency for our H2 database. R2DBC works with a reactive driver so it will integrate nicely with the rest of our application to allow us database access in a non-blocking way.

• reactor-core

  21 4,813 9.4 Java

  Non-Blocking Reactive Foundation for the JVM

  

Spring Framework is one of the most popular choices for web applications. It comes with a great ecosystem, tooling, and support. Spring applications are mainly written in Java. While they can serve quite well in many different domains and use cases, they may not be a good fit for modern-day applications which require low-latency and high-throughput. This is where the reactive programming paradigm could help because the paradigm is designed to address these issues by its non-blocking nature. Spring already supports reactive programming via Project Reactor.

• Flyway

  81 7,763 7.2 Java

  Flyway by Redgate • Database Migrations Made Easy.

  

Since we don't use JPA/Hibernate anymore, we will need to be handling our DB structure ourselves. Luckily, for a simple case like ours, Spring supports DB schema initialization directly (a real-world application might use a tool like Flyway for this purpose). Let's create a schema.sql in our resources folder:

• InfluxDB

  www.influxdata.com sponsored

  Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

  

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