The documentation you are viewing is for Dapr v1.13 which is an older version of Dapr. For up-to-date documentation, see the latest version.
Quickstart: Publish and Subscribe
Let’s take a look at Dapr’s Publish and Subscribe (Pub/sub) building block. In this Quickstart, you will run a publisher microservice and a subscriber microservice to demonstrate how Dapr enables a Pub/sub pattern.
- Using a publisher service, developers can repeatedly publish messages to a topic.
- A Pub/sub component queues or brokers those messages. Our example below uses Redis, you can use RabbitMQ, Kafka, etc.
- The subscriber to that topic pulls messages from the queue and processes them.
![](/images/pubsub-quickstart/pubsub-diagram.png)
You can try out this pub/sub quickstart by either:
- Running all applications in this sample simultaneously with the Multi-App Run template file, or
- Running one application at a time
Run using Multi-App Run
Select your preferred language-specific Dapr SDK before proceeding with the Quickstart.
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
From the root of the Quickstarts directory, navigate into the pub/sub directory:
cd pub_sub/python/sdk
Install the dependencies for the order-processor
and checkout
apps:
cd ./checkout
pip3 install -r requirements.txt
cd ..
cd ./order-processor
pip3 install -r requirements.txt
cd ..
cd ./order-processor-fastapi
pip3 install -r requirements.txt
cd ..
Step 3: Run the publisher and subscriber
With the following command, simultaneously run the following services alongside their own Dapr sidecars:
- The
order-processor
subscriber - The
checkout
publisher
dapr run -f .
Note: Since Python3.exe is not defined in Windows, you may need to change
python3
topython
in thedapr.yaml
file before runningdapr run -f .
Expected output
== APP - checkout-sdk == Published data: Order { OrderId = 1 }
== APP - order-processor == Subscriber received : Order { OrderId = 1 }
== APP - checkout-sdk == Published data: Order { OrderId = 2 }
== APP - order-processor == Subscriber received : Order { OrderId = 2 }
== APP - checkout-sdk == Published data: Order { OrderId = 3 }
== APP - order-processor == Subscriber received : Order { OrderId = 3 }
== APP - checkout-sdk == Published data: Order { OrderId = 4 }
== APP - order-processor == Subscriber received : Order { OrderId = 4 }
== APP - checkout-sdk == Published data: Order { OrderId = 5 }
== APP - order-processor == Subscriber received : Order { OrderId = 5 }
== APP - checkout-sdk == Published data: Order { OrderId = 6 }
== APP - order-processor == Subscriber received : Order { OrderId = 6 }
== APP - checkout-sdk == Published data: Order { OrderId = 7 }
== APP - order-processor == Subscriber received : Order { OrderId = 7 }
== APP - checkout-sdk == Published data: Order { OrderId = 8 }
== APP - order-processor == Subscriber received : Order { OrderId = 8 }
== APP - checkout-sdk == Published data: Order { OrderId = 9 }
== APP - order-processor == Subscriber received : Order { OrderId = 9 }
== APP - checkout-sdk == Published data: Order { OrderId = 10 }
== APP - order-processor == Subscriber received : Order { OrderId = 10 }
Exited App successfully
What happened?
When you ran dapr init
during Dapr install, the following YAML files were generated in the .dapr/components
directory:
Running dapr run -f .
in this Quickstart started both the subscriber and publisher applications.
dapr.yaml
Multi-App Run template file
Running the Multi-App Run template file with dapr run -f .
starts all applications in your project. In this Quickstart, the dapr.yaml
file contains the following:
version: 1
common:
resourcesPath: ../../components/
apps:
- appID: order-processor-sdk
appDirPath: ./order-processor/
appPort: 6001
command: ["uvicorn", "app:app"]
- appID: checkout-sdk
appDirPath: ./checkout/
command: ["python3", "app.py"]
pubsub.yaml
component file
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the component YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
order-processor
subscriber
In the order-processor
subscriber, you subscribe to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
# Register Dapr pub/sub subscriptions
@app.route('/dapr/subscribe', methods=['GET'])
def subscribe():
subscriptions = [{
'pubsubname': 'orderpubsub',
'topic': 'orders',
'route': 'orders'
}]
print('Dapr pub/sub is subscribed to: ' + json.dumps(subscriptions))
return jsonify(subscriptions)
# Dapr subscription in /dapr/subscribe sets up this route
@app.route('/orders', methods=['POST'])
def orders_subscriber():
event = from_http(request.headers, request.get_data())
print('Subscriber received : ' + event.data['orderid'], flush=True)
return json.dumps({'success': True}), 200, {
'ContentType': 'application/json'}
app.run(port=5001)
checkout
publisher
In the checkout
publisher, you publish the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
with DaprClient() as client:
# Publish an event/message using Dapr PubSub
result = client.publish_event(
pubsub_name='orderpubsub',
topic_name='orders',
data=json.dumps(order),
data_content_type='application/json',
)
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
From the root of the Quickstarts directory, navigate into the pub/sub directory:
cd pub_sub/javascript/sdk
Install the dependencies for the order-processor
and checkout
apps:
cd ./order-processor
npm install
cd ..
cd ./checkout
npm install
cd ..
Step 3: Run the publisher and subscriber
With the following command, simultaneously run the following services alongside their own Dapr sidecars:
- The
order-processor
subscriber - The
checkout
publisher
dapr run -f .
Expected output
== APP - checkout-sdk == Published data: Order { OrderId = 1 }
== APP - order-processor == Subscriber received : Order { OrderId = 1 }
== APP - checkout-sdk == Published data: Order { OrderId = 2 }
== APP - order-processor == Subscriber received : Order { OrderId = 2 }
== APP - checkout-sdk == Published data: Order { OrderId = 3 }
== APP - order-processor == Subscriber received : Order { OrderId = 3 }
== APP - checkout-sdk == Published data: Order { OrderId = 4 }
== APP - order-processor == Subscriber received : Order { OrderId = 4 }
== APP - checkout-sdk == Published data: Order { OrderId = 5 }
== APP - order-processor == Subscriber received : Order { OrderId = 5 }
== APP - checkout-sdk == Published data: Order { OrderId = 6 }
== APP - order-processor == Subscriber received : Order { OrderId = 6 }
== APP - checkout-sdk == Published data: Order { OrderId = 7 }
== APP - order-processor == Subscriber received : Order { OrderId = 7 }
== APP - checkout-sdk == Published data: Order { OrderId = 8 }
== APP - order-processor == Subscriber received : Order { OrderId = 8 }
== APP - checkout-sdk == Published data: Order { OrderId = 9 }
== APP - order-processor == Subscriber received : Order { OrderId = 9 }
== APP - checkout-sdk == Published data: Order { OrderId = 10 }
== APP - order-processor == Subscriber received : Order { OrderId = 10 }
Exited App successfully
What happened?
When you ran dapr init
during Dapr install, the following YAML files were generated in the .dapr/components
directory:
Running dapr run -f .
in this Quickstart started both the subscriber and publisher applications.
dapr.yaml
Multi-App Run template file
Running the Multi-App Run template file with dapr run -f .
starts all applications in your project. In this Quickstart, the dapr.yaml
file contains the following:
version: 1
common:
resourcesPath: ../../components/
apps:
- appID: order-processor
appDirPath: ./order-processor/
appPort: 5002
command: ["npm", "run", "start"]
- appID: checkout-sdk
appDirPath: ./checkout/
command: ["npm", "run", "start"]
pubsub.yaml
component file
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the component YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
order-processor
subscriber
In the order-processor
subscriber, you subscribe to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
server.pubsub.subscribe("orderpubsub", "orders", (data) => console.log("Subscriber received: " + JSON.stringify(data)));
checkout
publisher
In the checkout
publisher service, you publish the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
const client = new DaprClient();
await client.pubsub.publish(PUBSUB_NAME, PUBSUB_TOPIC, order);
console.log("Published data: " + JSON.stringify(order));
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
From the root of the Quickstarts directory, navigate into the pub/sub directory:
cd pub_sub/csharp/sdk
Install the dependencies for the order-processor
and checkout
apps:
cd ./order-processor
dotnet restore
dotnet build
cd ../checkout
dotnet restore
dotnet build
cd ..
Step 3: Run the publisher and subscriber
With the following command, simultaneously run the following services alongside their own Dapr sidecars:
- The
order-processor
subscriber - The
checkout
publisher
dapr run -f .
Expected output
== APP - checkout-sdk == Published data: Order { OrderId = 1 }
== APP - order-processor == Subscriber received : Order { OrderId = 1 }
== APP - checkout-sdk == Published data: Order { OrderId = 2 }
== APP - order-processor == Subscriber received : Order { OrderId = 2 }
== APP - checkout-sdk == Published data: Order { OrderId = 3 }
== APP - order-processor == Subscriber received : Order { OrderId = 3 }
== APP - checkout-sdk == Published data: Order { OrderId = 4 }
== APP - order-processor == Subscriber received : Order { OrderId = 4 }
== APP - checkout-sdk == Published data: Order { OrderId = 5 }
== APP - order-processor == Subscriber received : Order { OrderId = 5 }
== APP - checkout-sdk == Published data: Order { OrderId = 6 }
== APP - order-processor == Subscriber received : Order { OrderId = 6 }
== APP - checkout-sdk == Published data: Order { OrderId = 7 }
== APP - order-processor == Subscriber received : Order { OrderId = 7 }
== APP - checkout-sdk == Published data: Order { OrderId = 8 }
== APP - order-processor == Subscriber received : Order { OrderId = 8 }
== APP - checkout-sdk == Published data: Order { OrderId = 9 }
== APP - order-processor == Subscriber received : Order { OrderId = 9 }
== APP - checkout-sdk == Published data: Order { OrderId = 10 }
== APP - order-processor == Subscriber received : Order { OrderId = 10 }
Exited App successfully
What happened?
When you ran dapr init
during Dapr install, the following YAML files were generated in the .dapr/components
directory:
Running dapr run -f .
in this Quickstart started both the subscriber and publisher applications.
dapr.yaml
Multi-App Run template file
Running the Multi-App Run template file with dapr run -f .
starts all applications in your project. In this Quickstart, the dapr.yaml
file contains the following:
version: 1
common:
resourcesPath: ../../components/
apps:
- appID: order-processor
appDirPath: ./order-processor/
appPort: 7006
command: ["dotnet", "run"]
- appID: checkout-sdk
appDirPath: ./checkout/
command: ["dotnet", "run"]
pubsub.yaml
component file
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the component YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
order-processor
subscriber
In the order-processor
subscriber, you subscribe to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
// Dapr subscription in [Topic] routes orders topic to this route
app.MapPost("/orders", [Topic("orderpubsub", "orders")] (Order order) => {
Console.WriteLine("Subscriber received : " + order);
return Results.Ok(order);
});
public record Order([property: JsonPropertyName("orderId")] int OrderId);
checkout
publisher
In the checkout
publisher, you publish the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
using var client = new DaprClientBuilder().Build();
await client.PublishEventAsync("orderpubsub", "orders", order);
Console.WriteLine("Published data: " + order);
Step 1: Pre-requisites
For this example, you will need:
- Dapr CLI and initialized environment.
- Java JDK 17 (or greater):
- Oracle JDK, or
- OpenJDK
- Apache Maven, version 3.x.
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
From the root of the Quickstarts directory, navigate into the pub/sub directory:
cd pub_sub/java/sdk
Install the dependencies for the order-processor
and checkout
apps:
cd ./order-processor
mvn clean install
cd ..
cd ./checkout
mvn clean install
cd ..
Step 3: Run the publisher and subscriber
With the following command, simultaneously run the following services alongside their own Dapr sidecars:
- The
order-processor
subscriber - The
checkout
publisher
dapr run -f .
Expected output
== APP - checkout-sdk == Published data: Order { OrderId = 1 }
== APP - order-processor == Subscriber received : Order { OrderId = 1 }
== APP - checkout-sdk == Published data: Order { OrderId = 2 }
== APP - order-processor == Subscriber received : Order { OrderId = 2 }
== APP - checkout-sdk == Published data: Order { OrderId = 3 }
== APP - order-processor == Subscriber received : Order { OrderId = 3 }
== APP - checkout-sdk == Published data: Order { OrderId = 4 }
== APP - order-processor == Subscriber received : Order { OrderId = 4 }
== APP - checkout-sdk == Published data: Order { OrderId = 5 }
== APP - order-processor == Subscriber received : Order { OrderId = 5 }
== APP - checkout-sdk == Published data: Order { OrderId = 6 }
== APP - order-processor == Subscriber received : Order { OrderId = 6 }
== APP - checkout-sdk == Published data: Order { OrderId = 7 }
== APP - order-processor == Subscriber received : Order { OrderId = 7 }
== APP - checkout-sdk == Published data: Order { OrderId = 8 }
== APP - order-processor == Subscriber received : Order { OrderId = 8 }
== APP - checkout-sdk == Published data: Order { OrderId = 9 }
== APP - order-processor == Subscriber received : Order { OrderId = 9 }
== APP - checkout-sdk == Published data: Order { OrderId = 10 }
== APP - order-processor == Subscriber received : Order { OrderId = 10 }
Exited App successfully
What happened?
When you ran dapr init
during Dapr install, the following YAML files were generated in the .dapr/components
directory:
Running dapr run -f .
in this Quickstart started both the subscriber and publisher applications.
dapr.yaml
Multi-App Run template file
Running the Multi-App Run template file with dapr run -f .
starts all applications in your project. In this Quickstart, the dapr.yaml
file contains the following:
version: 1
common:
resourcesPath: ../../components/
apps:
- appID: order-processor-sdk
appDirPath: ./order-processor/target/
appPort: 8080
command: ["java", "-jar", "OrderProcessingService-0.0.1-SNAPSHOT.jar"]
- appID: checkout-sdk
appDirPath: ./checkout/target/
command: ["java", "-jar", "CheckoutService-0.0.1-SNAPSHOT.jar"]
pubsub.yaml
component file
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the component YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
order-processor
subscriber
In the order-processor
subscriber, you subscribe to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
@Topic(name = "orders", pubsubName = "orderpubsub")
@PostMapping(path = "/orders", consumes = MediaType.ALL_VALUE)
public Mono<ResponseEntity> getCheckout(@RequestBody(required = false) CloudEvent<Order> cloudEvent) {
return Mono.fromSupplier(() -> {
try {
logger.info("Subscriber received: " + cloudEvent.getData().getOrderId());
return ResponseEntity.ok("SUCCESS");
} catch (Exception e) {
throw new RuntimeException(e);
}
});
}
checkout
publisher
In the checkout
publisher, you publish the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
DaprClient client = new DaprClientBuilder().build();
client.publishEvent(
PUBSUB_NAME,
TOPIC_NAME,
order).block();
logger.info("Published data: " + order.getOrderId());
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
From the root of the Quickstarts directory, navigate into the pub/sub directory:
cd pub_sub/go/sdk
Install the dependencies for the order-processor
and checkout
apps:
cd ./order-processor
go build .
cd ../checkout
go build .
cd ..
Step 3: Run the publisher and subscriber
With the following command, simultaneously run the following services alongside their own Dapr sidecars:
- The
order-processor
subscriber - The
checkout
publisher
dapr run -f .
Expected output
== APP - checkout-sdk == Published data: Order { OrderId = 1 }
== APP - order-processor == Subscriber received : Order { OrderId = 1 }
== APP - checkout-sdk == Published data: Order { OrderId = 2 }
== APP - order-processor == Subscriber received : Order { OrderId = 2 }
== APP - checkout-sdk == Published data: Order { OrderId = 3 }
== APP - order-processor == Subscriber received : Order { OrderId = 3 }
== APP - checkout-sdk == Published data: Order { OrderId = 4 }
== APP - order-processor == Subscriber received : Order { OrderId = 4 }
== APP - checkout-sdk == Published data: Order { OrderId = 5 }
== APP - order-processor == Subscriber received : Order { OrderId = 5 }
== APP - checkout-sdk == Published data: Order { OrderId = 6 }
== APP - order-processor == Subscriber received : Order { OrderId = 6 }
== APP - checkout-sdk == Published data: Order { OrderId = 7 }
== APP - order-processor == Subscriber received : Order { OrderId = 7 }
== APP - checkout-sdk == Published data: Order { OrderId = 8 }
== APP - order-processor == Subscriber received : Order { OrderId = 8 }
== APP - checkout-sdk == Published data: Order { OrderId = 9 }
== APP - order-processor == Subscriber received : Order { OrderId = 9 }
== APP - checkout-sdk == Published data: Order { OrderId = 10 }
== APP - order-processor == Subscriber received : Order { OrderId = 10 }
Exited App successfully
What happened?
When you ran dapr init
during Dapr install, the following YAML files were generated in the .dapr/components
directory:
Running dapr run -f .
in this Quickstart started both the subscriber and publisher applications.
dapr.yaml
Multi-App Run template file
Running the Multi-App Run template file with dapr run -f .
starts all applications in your project. In this Quickstart, the dapr.yaml
file contains the following:
version: 1
common:
resourcesPath: ../../components/
apps:
- appID: order-processor
appDirPath: ./order-processor/
appPort: 6005
command: ["go", "run", "."]
- appID: checkout-sdk
appDirPath: ./checkout/
command: ["go", "run", "."]
pubsub.yaml
component file
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the component YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
order-processor
subscriber
In the order-processor
subscriber, you subscribe to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
func eventHandler(ctx context.Context, e *common.TopicEvent) (retry bool, err error) {
fmt.Println("Subscriber received: ", e.Data)
return false, nil
}
checkout
publisher
In the checkout
publisher, you publish the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
client, err := dapr.NewClient()
if err := client.PublishEvent(ctx, PUBSUB_NAME, PUBSUB_TOPIC, []byte(order)); err != nil {
panic(err)
}
fmt.Println("Published data: ", order)
Run one application at a time
Select your preferred language-specific Dapr SDK before proceeding with the Quickstart.
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
Step 3: Subscribe to topics
In a terminal window, from the root of the Quickstarts clone directory
navigate to the order-processor
directory.
cd pub_sub/python/sdk/order-processor
Install the dependencies:
pip3 install -r requirements.txt
Run the order-processor
subscriber service alongside a Dapr sidecar.
dapr run --app-id order-processor --resources-path ../../../components/ --app-port 6002 -- python3 app.py
Note: Since Python3.exe is not defined in Windows, you may need to use
python app.py
instead ofpython3 app.py
.
In the order-processor
subscriber, we’re subscribing to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
# Register Dapr pub/sub subscriptions
@app.route('/dapr/subscribe', methods=['GET'])
def subscribe():
subscriptions = [{
'pubsubname': 'orderpubsub',
'topic': 'orders',
'route': 'orders'
}]
print('Dapr pub/sub is subscribed to: ' + json.dumps(subscriptions))
return jsonify(subscriptions)
# Dapr subscription in /dapr/subscribe sets up this route
@app.route('/orders', methods=['POST'])
def orders_subscriber():
event = from_http(request.headers, request.get_data())
print('Subscriber received : ' + event.data['orderid'], flush=True)
return json.dumps({'success': True}), 200, {
'ContentType': 'application/json'}
app.run(port=5001)
Step 4: Publish a topic
In a new terminal window, navigate to the checkout
directory.
cd pub_sub/python/sdk/checkout
Install the dependencies:
pip3 install -r requirements.txt
Run the checkout
publisher service alongside a Dapr sidecar.
dapr run --app-id checkout --resources-path ../../../components/ -- python3 app.py
Note: Since Python3.exe is not defined in Windows, you may need to use
python app.py
instead ofpython3 app.py
.
In the checkout
publisher, we’re publishing the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
with DaprClient() as client:
# Publish an event/message using Dapr PubSub
result = client.publish_event(
pubsub_name='orderpubsub',
topic_name='orders',
data=json.dumps(order),
data_content_type='application/json',
)
Step 5: View the Pub/sub outputs
The publisher sends orders to the Dapr sidecar while the subscriber receives them.
Publisher output:
== APP == INFO:root:Published data: {"orderId": 1}
== APP == INFO:root:Published data: {"orderId": 2}
== APP == INFO:root:Published data: {"orderId": 3}
== APP == INFO:root:Published data: {"orderId": 4}
== APP == INFO:root:Published data: {"orderId": 5}
== APP == INFO:root:Published data: {"orderId": 6}
== APP == INFO:root:Published data: {"orderId": 7}
== APP == INFO:root:Published data: {"orderId": 8}
== APP == INFO:root:Published data: {"orderId": 9}
== APP == INFO:root:Published data: {"orderId": 10}
Subscriber output:
== APP == INFO:root:Subscriber received: {"orderId": 1}
== APP == INFO:root:Subscriber received: {"orderId": 2}
== APP == INFO:root:Subscriber received: {"orderId": 3}
== APP == INFO:root:Subscriber received: {"orderId": 4}
== APP == INFO:root:Subscriber received: {"orderId": 5}
== APP == INFO:root:Subscriber received: {"orderId": 6}
== APP == INFO:root:Subscriber received: {"orderId": 7}
== APP == INFO:root:Subscriber received: {"orderId": 8}
== APP == INFO:root:Subscriber received: {"orderId": 9}
== APP == INFO:root:Subscriber received: {"orderId": 10}
pubsub.yaml
component file
When you run dapr init
, Dapr creates a default Redis pubsub.yaml
and runs a Redis container on your local machine, located:
- On Windows, under
%UserProfile%\.dapr\components\pubsub.yaml
- On Linux/MacOS, under
~/.dapr/components/pubsub.yaml
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
Step 3: Subscribe to topics
In a terminal window, from the root of the Quickstarts clone directory
navigate to the order-processor
directory.
cd pub_sub/javascript/sdk/order-processor
Install dependencies, which will include the @dapr/dapr
package from the JavaScript SDK:
npm install
Verify you have the following files included in the service directory:
package.json
package-lock.json
Run the order-processor
subscriber service alongside a Dapr sidecar.
dapr run --app-port 5002 --app-id order-processing --app-protocol http --dapr-http-port 3501 --resources-path ../../../components -- npm run start
In the order-processor
subscriber, we’re subscribing to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
server.pubsub.subscribe("orderpubsub", "orders", (data) => console.log("Subscriber received: " + JSON.stringify(data)));
Step 4: Publish a topic
In a new terminal window, from the root of the Quickstarts clone directory,
navigate to the checkout
directory.
cd pub_sub/javascript/sdk/checkout
Install dependencies, which will include the @dapr/dapr
package from the JavaScript SDK:
npm install
Verify you have the following files included in the service directory:
package.json
package-lock.json
Run the checkout
publisher service alongside a Dapr sidecar.
dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 --resources-path ../../../components -- npm run start
In the checkout
publisher service, we’re publishing the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
const client = new DaprClient();
await client.pubsub.publish(PUBSUB_NAME, PUBSUB_TOPIC, order);
console.log("Published data: " + JSON.stringify(order));
Step 5: View the Pub/sub outputs
Notice, as specified in the code above, the publisher pushes a random number to the Dapr sidecar while the subscriber receives it.
Publisher output:
== APP == Published data: {"orderId":1}
== APP == Published data: {"orderId":2}
== APP == Published data: {"orderId":3}
== APP == Published data: {"orderId":4}
== APP == Published data: {"orderId":5}
== APP == Published data: {"orderId":6}
== APP == Published data: {"orderId":7}
== APP == Published data: {"orderId":8}
== APP == Published data: {"orderId":9}
== APP == Published data: {"orderId":10}
Subscriber output:
== APP == Subscriber received: {"orderId":1}
== APP == Subscriber received: {"orderId":2}
== APP == Subscriber received: {"orderId":3}
== APP == Subscriber received: {"orderId":4}
== APP == Subscriber received: {"orderId":5}
== APP == Subscriber received: {"orderId":6}
== APP == Subscriber received: {"orderId":7}
== APP == Subscriber received: {"orderId":8}
== APP == Subscriber received: {"orderId":9}
== APP == Subscriber received: {"orderId":10}
pubsub.yaml
component file
When you run dapr init
, Dapr creates a default Redis pubsub.yaml
and runs a Redis container on your local machine, located:
- On Windows, under
%UserProfile%\.dapr\components\pubsub.yaml
- On Linux/MacOS, under
~/.dapr/components/pubsub.yaml
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
Step 3: Subscribe to topics
In a terminal window, from the root of the Quickstarts clone directory
navigate to the order-processor
directory.
cd pub_sub/csharp/sdk/order-processor
Recall NuGet packages:
dotnet restore
dotnet build
Run the order-processor
subscriber service alongside a Dapr sidecar.
dapr run --app-id order-processor --resources-path ../../../components --app-port 7006 -- dotnet run
In the order-processor
subscriber, we’re subscribing to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
// Dapr subscription in [Topic] routes orders topic to this route
app.MapPost("/orders", [Topic("orderpubsub", "orders")] (Order order) => {
Console.WriteLine("Subscriber received : " + order);
return Results.Ok(order);
});
public record Order([property: JsonPropertyName("orderId")] int OrderId);
Step 4: Publish a topic
In a new terminal window, from the root of the Quickstarts clone directory,
navigate to the checkout
directory.
cd pub_sub/csharp/sdk/checkout
Recall NuGet packages:
dotnet restore
dotnet build
Run the checkout
publisher service alongside a Dapr sidecar.
dapr run --app-id checkout --resources-path ../../../components -- dotnet run
In the checkout
publisher, we’re publishing the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
using var client = new DaprClientBuilder().Build();
await client.PublishEventAsync("orderpubsub", "orders", order);
Console.WriteLine("Published data: " + order);
Step 5: View the Pub/sub outputs
Notice, as specified in the code above, the publisher pushes a random number to the Dapr sidecar while the subscriber receives it.
Publisher output:
== APP == Published data: Order { OrderId = 1 }
== APP == Published data: Order { OrderId = 2 }
== APP == Published data: Order { OrderId = 3 }
== APP == Published data: Order { OrderId = 4 }
== APP == Published data: Order { OrderId = 5 }
== APP == Published data: Order { OrderId = 6 }
== APP == Published data: Order { OrderId = 7 }
== APP == Published data: Order { OrderId = 8 }
== APP == Published data: Order { OrderId = 9 }
== APP == Published data: Order { OrderId = 10 }
Subscriber output:
== APP == Subscriber received: Order { OrderId = 1 }
== APP == Subscriber received: Order { OrderId = 2 }
== APP == Subscriber received: Order { OrderId = 3 }
== APP == Subscriber received: Order { OrderId = 4 }
== APP == Subscriber received: Order { OrderId = 5 }
== APP == Subscriber received: Order { OrderId = 6 }
== APP == Subscriber received: Order { OrderId = 7 }
== APP == Subscriber received: Order { OrderId = 8 }
== APP == Subscriber received: Order { OrderId = 9 }
== APP == Subscriber received: Order { OrderId = 10 }
pubsub.yaml
component file
When you run dapr init
, Dapr creates a default Redis pubsub.yaml
and runs a Redis container on your local machine, located:
- On Windows, under
%UserProfile%\.dapr\components\pubsub.yaml
- On Linux/MacOS, under
~/.dapr/components/pubsub.yaml
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
In the YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
Step 1: Pre-requisites
For this example, you will need:
- Dapr CLI and initialized environment.
- Java JDK 17 (or greater):
- Oracle JDK, or
- OpenJDK
- Apache Maven, version 3.x.
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
Step 3: Subscribe to topics
In a terminal window, from the root of the Quickstarts clone directory
navigate to the order-processor
directory.
cd pub_sub/java/sdk/order-processor
Install the dependencies:
mvn clean install
Run the order-processor
subscriber service alongside a Dapr sidecar.
dapr run --app-port 8080 --app-id order-processor --resources-path ../../../components -- java -jar target/OrderProcessingService-0.0.1-SNAPSHOT.jar
In the order-processor
subscriber, we’re subscribing to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
@Topic(name = "orders", pubsubName = "orderpubsub")
@PostMapping(path = "/orders", consumes = MediaType.ALL_VALUE)
public Mono<ResponseEntity> getCheckout(@RequestBody(required = false) CloudEvent<Order> cloudEvent) {
return Mono.fromSupplier(() -> {
try {
logger.info("Subscriber received: " + cloudEvent.getData().getOrderId());
return ResponseEntity.ok("SUCCESS");
} catch (Exception e) {
throw new RuntimeException(e);
}
});
}
Step 4: Publish a topic
In a new terminal window, from the root of the Quickstarts clone directory,
navigate to the checkout
directory.
cd pub_sub/java/sdk/checkout
Install the dependencies:
mvn clean install
Run the checkout
publisher service alongside a Dapr sidecar.
dapr run --app-id checkout --resources-path ../../../components -- java -jar target/CheckoutService-0.0.1-SNAPSHOT.jar
In the checkout
publisher, we’re publishing the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
DaprClient client = new DaprClientBuilder().build();
client.publishEvent(
PUBSUB_NAME,
TOPIC_NAME,
order).block();
logger.info("Published data: " + order.getOrderId());
Step 5: View the Pub/sub outputs
Notice, as specified in the code above, the publisher pushes a random number to the Dapr sidecar while the subscriber receives it.
Publisher output:
== APP == 7194 [main] INFO com.service.CheckoutServiceApplication - Published data: 1
== APP == 12213 [main] INFO com.service.CheckoutServiceApplication - Published data: 2
== APP == 17233 [main] INFO com.service.CheckoutServiceApplication - Published data: 3
== APP == 22252 [main] INFO com.service.CheckoutServiceApplication - Published data: 4
== APP == 27276 [main] INFO com.service.CheckoutServiceApplication - Published data: 5
== APP == 32320 [main] INFO com.service.CheckoutServiceApplication - Published data: 6
== APP == 37340 [main] INFO com.service.CheckoutServiceApplication - Published data: 7
== APP == 42356 [main] INFO com.service.CheckoutServiceApplication - Published data: 8
== APP == 47386 [main] INFO com.service.CheckoutServiceApplication - Published data: 9
== APP == 52410 [main] INFO com.service.CheckoutServiceApplication - Published data: 10
Subscriber output:
== APP == 2022-03-07 13:31:19.551 INFO 43512 --- [nio-8080-exec-5] c.s.c.OrderProcessingServiceController : Subscriber received: 1
== APP == 2022-03-07 13:31:19.552 INFO 43512 --- [nio-8080-exec-9] c.s.c.OrderProcessingServiceController : Subscriber received: 2
== APP == 2022-03-07 13:31:19.551 INFO 43512 --- [nio-8080-exec-6] c.s.c.OrderProcessingServiceController : Subscriber received: 3
== APP == 2022-03-07 13:31:19.552 INFO 43512 --- [nio-8080-exec-2] c.s.c.OrderProcessingServiceController : Subscriber received: 4
== APP == 2022-03-07 13:31:19.553 INFO 43512 --- [nio-8080-exec-2] c.s.c.OrderProcessingServiceController : Subscriber received: 5
== APP == 2022-03-07 13:31:19.553 INFO 43512 --- [nio-8080-exec-9] c.s.c.OrderProcessingServiceController : Subscriber received: 6
== APP == 2022-03-07 13:31:22.849 INFO 43512 --- [nio-8080-exec-3] c.s.c.OrderProcessingServiceController : Subscriber received: 7
== APP == 2022-03-07 13:31:27.866 INFO 43512 --- [nio-8080-exec-6] c.s.c.OrderProcessingServiceController : Subscriber received: 8
== APP == 2022-03-07 13:31:32.895 INFO 43512 --- [nio-8080-exec-6] c.s.c.OrderProcessingServiceController : Subscriber received: 9
== APP == 2022-03-07 13:31:37.919 INFO 43512 --- [nio-8080-exec-2] c.s.c.OrderProcessingServiceController : Subscriber received: 10
pubsub.yaml
component file
When you run dapr init
, Dapr creates a default Redis pubsub.yaml
and runs a Redis container on your local machine, located:
- On Windows, under
%UserProfile%\.dapr\components\pubsub.yaml
- On Linux/MacOS, under
~/.dapr/components/pubsub.yaml
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
scopes:
- orderprocessing
- checkout
In the YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
Step 1: Pre-requisites
For this example, you will need:
Step 2: Set up the environment
Clone the sample provided in the Quickstarts repo.
git clone https://github.com/dapr/quickstarts.git
Step 3: Subscribe to topics
In a terminal window, from the root of the Quickstarts clone directory
navigate to the order-processor
directory.
cd pub_sub/go/sdk/order-processor
Install the dependencies and build the application:
go build .
Run the order-processor
subscriber service alongside a Dapr sidecar.
dapr run --app-port 6005 --app-id order-processor-sdk --app-protocol http --dapr-http-port 3501 --resources-path ../../../components -- go run .
In the order-processor
subscriber, we’re subscribing to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. This enables your app code to talk to the Redis component instance through the Dapr sidecar.
func eventHandler(ctx context.Context, e *common.TopicEvent) (retry bool, err error) {
fmt.Println("Subscriber received: ", e.Data)
return false, nil
}
Step 4: Publish a topic
In a new terminal window, from the root of the Quickstarts clone directory,
navigate to the checkout
directory.
cd pub_sub/go/sdk/checkout
Install the dependencies and build the application:
go build .
Run the checkout
publisher service alongside a Dapr sidecar.
dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 --resources-path ../../../components -- go run .
In the checkout
publisher, we’re publishing the orderId message to the Redis instance called orderpubsub
(as defined in the pubsub.yaml
component) and topic orders
. As soon as the service starts, it publishes in a loop:
client, err := dapr.NewClient()
if err := client.PublishEvent(ctx, PUBSUB_NAME, PUBSUB_TOPIC, []byte(order)); err != nil {
panic(err)
}
fmt.Println("Published data: ", order)
Step 5: View the Pub/sub outputs
Notice, as specified in the code above, the publisher pushes a numbered message to the Dapr sidecar while the subscriber receives it.
Publisher output:
== APP == dapr client initializing for: 127.0.0.1:63293
== APP == Published data: {"orderId":1}
== APP == Published data: {"orderId":2}
== APP == Published data: {"orderId":3}
== APP == Published data: {"orderId":4}
== APP == Published data: {"orderId":5}
== APP == Published data: {"orderId":6}
== APP == Published data: {"orderId":7}
== APP == Published data: {"orderId":8}
== APP == Published data: {"orderId":9}
== APP == Published data: {"orderId":10}
Subscriber output:
== APP == Subscriber received: {"orderId":1}
== APP == Subscriber received: {"orderId":2}
== APP == Subscriber received: {"orderId":3}
== APP == Subscriber received: {"orderId":4}
== APP == Subscriber received: {"orderId":5}
== APP == Subscriber received: {"orderId":6}
== APP == Subscriber received: {"orderId":7}
== APP == Subscriber received: {"orderId":8}
== APP == Subscriber received: {"orderId":9}
== APP == Subscriber received: {"orderId":10}
Note: the order in which they are received may vary.
pubsub.yaml
component file
When you run dapr init
, Dapr creates a default Redis pubsub.yaml
and runs a Redis container on your local machine, located:
- On Windows, under
%UserProfile%\.dapr\components\pubsub.yaml
- On Linux/MacOS, under
~/.dapr/components/pubsub.yaml
With the pubsub.yaml
component, you can easily swap out underlying components without application code changes.
The Redis pubsub.yaml
file included for this Quickstart contains the following:
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: orderpubsub
spec:
type: pubsub.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
scopes:
- orderprocessing
- checkout
In the YAML file:
metadata/name
is how your application talks to the component.spec/metadata
defines the connection to the instance of the component.scopes
specify which application can use the component.
Tell us what you think!
We’re continuously working to improve our Quickstart examples and value your feedback. Did you find this Quickstart helpful? Do you have suggestions for improvement?
Join the discussion in our discord channel.
Next steps
- Set up Pub/sub using HTTP instead of an SDK.
- Learn more about Pub/sub as a Dapr building block
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