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updating spring boot integration docs for Java SDK
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salaboy committed Sep 10, 2024
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Expand Up @@ -8,10 +8,10 @@ description: How to get started with Dapr and Spring Boot

By combining Dapr and Spring Boot, we can create infrastructure independent Java applications that can be deployed across different environments, supporting a wide range of on-premises and cloud provider services.

First, we will start with a simple integration covering the DaprClient and the Testcontainers integration, to then use Spring and Spring Boot mechanisms and programming model to leverage the Dapr APIs under the hood. This help teams to remove dependencies such as clients and drivers required to connect to environment specific infrastructure (databases, key-value stores, message brokers, configuration/secret stores, etc.)
First, we will start with a simple integration covering the `DaprClient` and the [Testcontainers](https://testcontainers.com/) integration, to then use Spring and Spring Boot mechanisms and programming model to leverage the Dapr APIs under the hood. This help teams to remove dependencies such as clients and drivers required to connect to environment specific infrastructure (databases, key-value stores, message brokers, configuration/secret stores, etc.)

{{% alert title="Note" color="primary" %}}
@TODO: If you haven't already, [try out one of the quickstarts]({{< ref quickstarts >}}) for a quick walk-through on how to use the Dapr and Spring Boot.
The Spring Boot integration explained in this page is still alpha, hence most artifacts are labeled with 0.13.0.

{{% /alert %}}

Expand All @@ -22,27 +22,25 @@ If you already have a Spring Boot application (Spring Boot 3.x+), you can direct


```
<dependency>
<groupId>io.dapr</groupId>
<artifactId>dapr-spring-boot-starter</artifactId>
<version>${dapr-java-sdk.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.dapr</groupId>
<artifactId>testcontainers-dapr</artifactId>
<version>${dapr-java-sdk.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.dapr.spring</groupId>
<artifactId>dapr-spring-boot-starter</artifactId>
<version>0.13.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>io.dapr.spring</groupId>
<artifactId>dapr-spring-boot-starter-test</artifactId>
<version>0.13.0-SNAPSHOT</version>
<scope>test</scope>
</dependency>
```

By adding these dependencies you can:
- Autowire a DaprClient to use inside your applications
- Autowire a `DaprClient` to use inside your applications
- Use the Spring Data and Messaging abstractions and programming model that uses the Dapr APIs under the hood
- Improve your inner-development loop by relying on Testcontainers to bootstrap Dapr Control plane services and default components
- (Work in progress) Wire up workflow activities using the Spring programming model
- Improve your inner-development loop by relying on [Testcontainers](https://testcontainers.com/) to bootstrap Dapr Control plane services and default components

Once this dependencies are in your application, you can rely on Spring Boot autoconfiguration to autowire a `DaprClient` instance:
Once these dependencies are in your application, you can rely on Spring Boot autoconfiguration to autowire a `DaprClient` instance:

```java
@Autowired
Expand All @@ -52,7 +50,7 @@ private DaprClient daprClient;

This will connect to the default Dapr gRPC endpoint `localhost:50001`, requiring you to start Dapr outside of your application.

You can use the DaprClient to interact with the Dapr APIs anywhere in your application, for example from inside a REST endpoint:
You can use the `DaprClient` to interact with the Dapr APIs anywhere in your application, for example from inside a REST endpoint:

```java
@RestController
Expand All @@ -69,92 +67,217 @@ public class DemoRestController {
record Order(String orderId, Integer amount){}
```

If you want to avoid managing Dapr outside of your Spring Boot application, you can rely on Testcontainers to bootstrap Dapr besides your application for development purposes. To do this we can create a test configuration that uses Testcontainers to bootstrap all we need to develop our applications using the Dapr APIs.
If you want to avoid managing Dapr outside of your Spring Boot application, you can rely on [Testcontainers](https://testcontainers.com/) to bootstrap Dapr besides your application for development purposes.
To do this we can create a test configuration that uses `Testcontainers` to bootstrap all we need to develop our applications using the Dapr APIs.

Using Testcontaniners and Dapr integrations, we let the test configuration to bootstrap Dapr for our applications.
Using [Testcontaniners](https://testcontainers.com/) and Dapr integrations, we let the `@TestConfiguration` to bootstrap Dapr for our applications.
Notice that for this example, we are configuring Dapr with a Statestore component called `kvstore` that connects to an instance of `PostgreSQL` also bootstrapped by Testcontainers.

```java
@Configuration
interface MyTestConfiguration {

@Container
DaprContainer dapr = new DaprContainer("daprio/daprd:1.13.2")
.withAppName("local-dapr-app")
//Enable Workflows
.withComponent(new Component("kvstore", "state.in-memory", "v1",
Collections.singletonMap("actorStateStore", "true")))
.withComponent(new Component("pubsub", "pubsub.in-memory", "v1", Collections.emptyMap()))
.withAppPort(8080)
.withDaprLogLevel(DaprLogLevel.DEBUG)
.withAppChannelAddress("host.testcontainers.internal");

/**
* Expose the Dapr ports to the host.
*
* @param registry the dynamic property registry
*/
@DynamicPropertySource
static void daprProperties(DynamicPropertyRegistry registry) {
Testcontainers.exposeHostPorts(8080);
dapr.start();
registry.add()
registry.add()
}
@TestConfiguration(proxyBeanMethods = false)
public class DaprTestContainersConfig {
@Bean
@ServiceConnection
public DaprContainer daprContainer(Network daprNetwork, PostgreSQLContainer<?> postgreSQLContainer){

return new DaprContainer("daprio/daprd:1.14.1")
.withAppName("producer-app")
.withNetwork(daprNetwork)
.withComponent(new Component("kvstore", "state.postgresql", "v1", STATE_STORE_PROPERTIES))
.withComponent(new Component("kvbinding", "bindings.postgresql", "v1", BINDING_PROPERTIES))
.dependsOn(postgreSQLContainer);
}
}
```

Inside the test classpath you can add a new Spring Boot Application that uses this configuration for tests:

```java
@SpringBootApplication
public class TestProducerApplication {

public static void main(String[] args) {

SpringApplication
.from(ProducerApplication::main)
.with(DaprTestContainersConfig.class)
.run(args);
}

}
```

Now you can start your application with:
```bash
mvn spring-boot:test-run
```

Running this command will start the application, using the provided test configuration that includes the Testcontainers and Dapr integration. In the logs you should be able to see that the daprd and the placement service containers were started for your application.
Running this command will start the application, using the provided test configuration that includes the Testcontainers and Dapr integration. In the logs you should be able to see that the `daprd` and the `placement` service containers were started for your application.

Besides the previous configuration (`DaprTestContainersConfig`) your tests shouldn't be testing Dapr itself, just the REST endpoints that your application is exposing.


## Leveraging Spring & Spring Boot programming model with Dapr

The Java SDK allows you to interface with all of the [Dapr building blocks]({{< ref building-blocks >}}). But if you want to leverage the Spring and Spring Boot programming model you can use the `dapr-spring-boot-starter` integration. This includes implementations of Spring Data (KeyValueTemplate and CrudRepository) as well as a Messaging Template for producing and consuming messages (similar to Spring Kafka, Spring Pulsar and Spring AMQP).
The Java SDK allows you to interface with all of the [Dapr building blocks]({{< ref building-blocks >}}).
But if you want to leverage the Spring and Spring Boot programming model you can use the `dapr-spring-boot-starter` integration.
This includes implementations of Spring Data (`KeyValueTemplate` and `CrudRepository`) as well as a `DaprMessagingTemplate` for producing and consuming messages
(similar to [Spring Kafka](https://spring.io/projects/spring-kafka), [Spring Pulsar](https://spring.io/projects/spring-pulsar) and [Spring AMQP for RabbitMQ](https://spring.io/projects/spring-amqp)).

## Using Spring Data CrudRepository and KeyValueTemplate
## Using Spring Data `CrudRepository` and `KeyValueTemplate`

You can use well known Spring Data constructs relying on a Dapr-based implementation. With Dapr, you don't need to add any infrastructure-related driver or client, making your Spring application lighter and decoupled from the environment where it is running.
You can use well known Spring Data constructs relying on a Dapr-based implementation.
With Dapr, you don't need to add any infrastructure-related driver or client, making your Spring application lighter and decoupled from the environment where it is running.

Under the hood these implementations uses Dapr Statestore and Binding APIs.

### Configuration parameters

With Spring Data abstractions you can configure which statestore and bindings will be used by Dapr to connect to the available infrastructure. This can be done by setting the following properties:
With Spring Data abstractions you can configure which statestore and bindings will be used by Dapr to connect to the available infrastructure.
This can be done by setting the following properties:

## Using Spring Messaging for producing and consuming events
```properties
dapr.statestore.name=kvstore
dapr.statestore.binding=kvbinding
```

Similar to Spring Kafka, Spring Pulsar and Spring AMQP you can use the DaprMessagingTemplate to publish messages to the configured infrastructure. To consume messages you can use the `@DaprListener` annotation.
Then you can `@Autowire` a `KeyValueTemplate` or a `CrudRepository` like this:

To publish events/messages you can `@Autowire` the `DaprMessagingTemplate` in your Spring application.
```java
@RestController
@EnableDaprRepositories
public class OrdersRestController {
@Autowired
private OrderRepository repository;

@PostMapping("/orders")
public void storeOrder(@RequestBody Order order){
repository.save(order);
}

@GetMapping("/orders")
public Iterable<Order> getAll(){
return repository.findAll();
}


}
```

Where `OrderRepository` is defined in an interface that extends the Spring Data `CrudRepository` interface:

```java
public interface OrderRepository extends CrudRepository<Order, String> {}
```

To listen to events/messages you need to expose an endpoint in the application that will be resposible to receive the messages. If you expose a REST endpoint you can use the `@DaprListener` annotation to let Dapr know where it needs to forward the events/messages too:
Notice that `@EnableDaprRepositories` annotation, that does all the magic of wiring the Dapr APIs under the `CrudRespository` interface.
Because Dapr allow users to interact with different StateStores from the same application, as a user you need to provide the following beans as a Spring Boot `@Configuration`:

```java
@Configuration
@EnableConfigurationProperties({DaprStateStoreProperties.class})
public class ProducerAppConfiguration {

@Bean
public KeyValueAdapterResolver keyValueAdapterResolver(DaprClient daprClient, ObjectMapper mapper, DaprStateStoreProperties daprStatestoreProperties) {
String storeName = daprStatestoreProperties.getName();
String bindingName = daprStatestoreProperties.getBinding();

return new DaprKeyValueAdapterResolver(daprClient, mapper, storeName, bindingName);
}

@Bean
public DaprKeyValueTemplate daprKeyValueTemplate(KeyValueAdapterResolver keyValueAdapterResolver) {
return new DaprKeyValueTemplate(keyValueAdapterResolver);
}

}
```

## Using Spring Messaging for producing and consuming events

Similar to Spring Kafka, Spring Pulsar and Spring AMQP you can use the `DaprMessagingTemplate` to publish messages to the configured infrastructure. To consume messages you can use the `@Topic` annotation (soon to be renamed to `@DaprListener`).

To publish events/messages you can `@Autowired` the `DaprMessagingTemplate` in your Spring application.
For this example we will be publishing `Order` events and we are sending messages to the topic named `topic`.

```java
@Autowired
private DaprMessagingTemplate<Order> messagingTemplate;

@PostMapping("/orders")
public void storeOrder(@RequestBody Order order){
repository.save(order);
messagingTemplate.send("topic", order);
}

```

Check the following example to see how, leveraging the Testcontainers integration, you can test Spring Boot applications that publish and consume messages/events without the need of including any drivers or clients or managing connections.
Similarly to the `CrudRepository` we need to specify which PubSub broker do we want to use to publish and consume our messages.

```properties
dapr.pubsub.name=pubsub
```

Because with Dapr you can connect to multiple PubSub brokers you need to provide the following bean to let Dapr know which PubSub broker your `DaprMessagingTemplate` will use:
```java
@Bean
public DaprMessagingTemplate<Order> messagingTemplate(DaprClient daprClient,
DaprPubSubProperties daprPubSubProperties) {
return new DaprMessagingTemplate<>(daprClient, daprPubSubProperties.getName());
}
```

Finally, because Dapr PubSub requires a bidirectional connection between your application and Dapr you need to expand your Testcontainers configuration with a few parameters:

### Configuration parameters
```java
@Bean
@ServiceConnection
public DaprContainer daprContainer(Network daprNetwork, PostgreSQLContainer<?> postgreSQLContainer, RabbitMQContainer rabbitMQContainer){

return new DaprContainer("daprio/daprd:1.14.1")
.withAppName("producer-app")
.withNetwork(daprNetwork)
.withComponent(new Component("kvstore", "state.postgresql", "v1", STATE_STORE_PROPERTIES))
.withComponent(new Component("kvbinding", "bindings.postgresql", "v1", BINDING_PROPERTIES))
.withComponent(new Component("pubsub", "pubsub.rabbitmq", "v1", rabbitMqProperties))
.withAppPort(8080)
.withAppChannelAddress("host.testcontainers.internal")
.dependsOn(rabbitMQContainer)
.dependsOn(postgreSQLContainer);
}
```

Now, in the Dapr configuration we have included a `pubsub` component that will connect to an instance of RabbitMQ started by Testcontainers.
We have also set two important parameters `.withAppPort(8080)` and `.withAppChannelAddress("host.testcontainers.internal")` which allows Dapr to
contact back to the application when a message is published in the broker.

With Spring Kafka, Pulsar, and AMQP abstractions you can configure which pubsub will be used by Dapr to connect to the available infrastructure. This can be done by setting the following properties:
To listen to events/messages you need to expose an endpoint in the application that will be responsible to receive the messages.
If you expose a REST endpoint you can use the `@Topic` annotation to let Dapr know where it needs to forward the events/messages too:

### Comparison with Spring Kafka, Spring RabbitMQ and Spring AMQP
```java
@PostMapping("subscribe")
@Topic(pubsubName = "pubsub", name = "topic")
public void subscribe(@RequestBody CloudEvent<Order> cloudEvent){
events.add(cloudEvent);
}
```

On bootstrapping your application, Dapr will register the subscription to messages to be forwarded to the `subscribe` endpoint exposed by your application.

If you are writing tests got these subscribers you need to make sure that let Testcontainers know that your application will be running in port 8080,
so containers started with Testcontainers know where your application is:

## Next steps
```java
@BeforeAll
public static void setup(){
org.testcontainers.Testcontainers.exposeHostPorts(8080);
}
```

You can check and run the [full example source code here](https://github.com/salaboy/dapr-spring-boot-docs-examples).

## Next steps

Learn more about the [Dapr Java SDK packages available to add to your Java applications](https://dapr.github.io/java-sdk/).

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