Spring Boot Starter

6.0-SNAPSHOT 5.5 5.4 5.3 5.2 5.1 5.0

Spring Boot makes it easy to create and use third-party libraries, such as Hazelcast, with minimum configurations possible. While Spring Boot provides starters for some libraries, Hazelcast hosts its own starter.

Let’s create a simple Spring Boot application which starts a Hazelcast member and auto-wires it.

1. Create a New Java Project

We assume you’re using an IDE. Create a blank Java project named tutorial-jet-starter and copy the Gradle or Maven file into it:

  • Gradle

  • Maven

plugins {
  id 'org.springframework.boot' version '2.2.6.RELEASE'
  id 'io.spring.dependency-management' version '1.0.9.RELEASE'
  id 'java'
}
group = 'org.example'
version '1.0-SNAPSHOT'

repositories.mavenCentral()

dependencies {
  implementation 'com.hazelcast.jet.contrib:hazelcast-jet-spring-boot-starter:2.0.0'
}
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.6.RELEASE</version>
    <relativePath/>
  </parent>

  <groupId>org.example</groupId>
  <artifactId>tutorial-jet-starter</artifactId>
  <version>1.0-SNAPSHOT</version>

  <dependencies>
    <dependency>
        <groupId>com.hazelcast.jet.contrib</groupId>
        <artifactId>hazelcast-jet-spring-boot-starter</artifactId>
        <version>2.0.0</version>
    </dependency>
  </dependencies>
</project>

2. Create the Application Main Class

The following code creates a Spring Boot application which starts a Jet member with default configuration.

package org.example;

import com.hazelcast.jet.JetService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TutorialApplication {

    @Autowired
    JetService jet;

    public static void main(String[] args) {
        SpringApplication.run(TutorialApplication.class, args);
    }
}

When you run it on your IDE, you should see in the logs that a Hazelcast member is started and the default configuration file is used:

...
c.h.i.config.AbstractConfigLocator       : Loading 'hazelcast-jet-default.xml' from the classpath.
...
c.h.i.config.AbstractConfigLocator       : Loading 'hazelcast-jet-member-default.xml' from the classpath.
...

3. Custom Configuration

Let’s add some custom configuration to our Hazelcast member by defining a configuration file named hazelcast.yaml at the root directory.

hazelcast:
  jet:
    instance:
      cooperative-thread-count: 4
      edge-defaults:
      queue-size: 2048

To configure the underlying HazelcastInstance we’ll define a configuration file named hazelcast.yaml at the root directory.

hazelcast:
  cluster-name: tutorial-jet-starter

When you stop and re-run the main class you should now see that the configuration files we’ve just created is used to start the member:

...
c.h.i.config.AbstractConfigLocator       : Loading 'hazelcast.yaml' from the working directory.
...
c.h.i.config.AbstractConfigLocator       : Loading 'hazelcast.yaml' from the working directory.
...

Using Properties File

If your configuration files are not at the root directory or you want to use a different name then you can create an application.properties file and set the hazelcast.jet.server.config and hazelcast.jet.imdg.config like below:

hazelcast.jet.server.config=file:config/hazelcast-jet-tutorial.yaml
hazelcast.jet.imdg.config=file:config/hazelcast-tutorial.yaml

Since Spring Boot converts these config properties to resource URLs, you need to use file: prefix for files at the working directory and classpath: for files on the classpath.

Using System Properties

You can also set configuration files using system property:

System.setProperty("hazelcast.jet.config", "config/hazelcast-jet-tutorial.yaml");
System.setProperty("hazelcast.config", "config/hazelcast-tutorial.yaml");

This will work if your configuration files are at the working directory. If they are on the classpath you should use classpath: prefix.

4. Hazelcast Client

If you have a Hazelcast cluster already running and want to connect to it with a client all you need to do is to put a client configuration file (hazelcast-client.yaml) to the root directory instead of the Hazelcast configuration:

hazelcast-client:
  cluster-name: tutorial-jet-starter
  network:
    cluster-members:
      - 127.0.0.1

Using Properties File

If your configuration file is not at the root directory or you want to use a different name then you can create an application.properties file and set the hazelcast.jet.client.config like below:

hazelcast.jet.client.config=file:config/hazelcast-client-tutorial.yaml

You need to use file: prefix for files at the working directory and classpath: for files on the classpath.

Using System Properties

You can also set configuration file using system property:

System.setProperty("hazelcast.client.config", "config/hazelcast-client-tutorial.yaml");

If configuration file is on the classpath you should use classpath: prefix.

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