Starters are available as Maven artifacts in the Spring repositories. You can add them as dependencies to your application, as follows:

<dependency>
  <group>org.springframework.cloud.stream.app</group>
  <artifactId>spring-cloud-starter-stream-sink-cassandra</artifactId>
  <version>1.0.0.BUILD-SNAPSHOT</version>
</dependency>

From this, you can infer the coordinates for other starters found in this guide. While the version may vary, the group will always remain org.springframework.cloud.stream.app and the artifact id follows the naming convention spring-cloud-starter-stream-<type>-<functionality> described previously.

Prebuilt applications are available as Maven artifacts too. It is not encouraged to use them directly as dependencies, as starters should be used instead. Following the typical Maven <group>:<artifactId>:<version> convention, they can be referenced for example as:

org.springframework.cloud.stream.app:cassandra-sink-rabbit:1.0.0.BUILD-SNAPSHOT

Just as with the starters, you can infer the coordinates for other prebuilt applications found in the guide. The group will be always org.springframework.cloud.stream.app. The version may vary. The artifact id follows the format <functionality>-<type>-<binder> previously described.

The Docker versions of the applications are available in Docker Hub, at hub.docker.com/r/springcloudstream/. Naming and versioning follows the same general conventions as Maven, e.g.

docker pull springcloudstream/cassandra-sink-kafka

will pull the latest Docker image of the Cassandra sink with the Kafka binder.

You can also build the project and generate the artifacts (including the prebuilt applications) on your own. This is useful if you want to deploy the artifacts locally, for example for adding a new starter, or if you want to build the entire set of artifacts with a new binder.

First, you need to generate the prebuilt applications. This is done by running the application generation Maven plugin. You can do so by simply invoking the corresponding script in the root of the project.

./generate.sh

For the each of the prebuilt applications, the script will generate the following items:

For example, spring-cloud-starter-stream-sink-cassandra will generate cassandra-sink-rabbit and cassandra-sink-kafka as completely functional applications.

If you want to use one of the applications found in Spring Cloud Stream Application Starters and you want to use one of the predefined binders (i.e. Kafka or Rabbit), you can just use the prebuilt versions of the artifacts. But if you want to connect to a different middleware system, and you have a binder for it, you will create new artifacts.

<dependencies>
  <!- other dependencies -->
  <dependency>
    <groupId>org.springframework.cloud.stream.app</groupId>
    <artifactId>spring-cloud-starter-stream-sink-cassandra</artifactId>
    <version>1.0.0.BUILD-SNAPSHOT</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-stream-binder-gemfire</artifactId>
    <version>1.0.0.BUILD-SNAPSHOT</version>
  </dependency>
</dependencies>

The next step is to create the project’s main class and import the configuration provided by the starter. For example, in the same case of the Cassandra sink it can look like the following:

package org.springframework.cloud.stream.app.cassandra.sink.rabbit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.stream.app.cassandra.sink.CassandraSinkConfiguration;
import org.springframework.context.annotation.Import;


@SpringBootApplication
@Import(CassandraSinkConfiguration.class)
public class CassandraSinkGemfireApplication {

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

Spring Cloud Stream Application Starters consists of regular Spring Cloud Stream applications with some additional conventions that facilitate generating prebuilt applications with the preconfigured binders. Sometimes, your solution may require additional applications that are not in the scope of Spring Cloud Stream Application Starters, or require additional tweaks and enhancements. In this section we will show you how to create custom applications that can be part of your solution, along with Spring Cloud Stream application starters. You have the following options: