Quickstart: Service Invocation

Get started with Dapr’s Service Invocation building block

With Dapr’s Service Invocation building block, your application can communicate reliably and securely with other applications.

Diagram showing the steps of service invocation

Dapr offers several methods for service invocation, which you can choose depending on your scenario. For this Quickstart, you’ll enable the checkout service to invoke a method using HTTP proxy in the order-processor service and by either:

Learn more about Dapr’s methods for service invocation in the overview article.

Run using Multi-App Run

Select your preferred language 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 Quickstart clone directory, navigate to the quickstart directory.

cd service_invocation/python/http

Install the dependencies for the order-processor and checkout apps:

cd ./order-processor
pip3 install -r requirements.txt
cd ../checkout
pip3 install -r requirements.txt
cd ..

Step 3: Run the order-processor and checkout services

With the following command, simultaneously run the following services alongside their own Dapr sidecars:

  • The order-processor service
  • The checkout service
dapr run -f .

Note: Since Python3.exe is not defined in Windows, you may need to change python3 to python in the dapr.yaml file before running dapr run -f .

Expected output

== APP - order-processor == Order received : Order { orderId = 1 }
== APP - checkout == Order passed: Order { OrderId = 1 }
== APP - order-processor == Order received : Order { orderId = 2 }
== APP - checkout == Order passed: Order { OrderId = 2 }
== APP - order-processor == Order received : Order { orderId = 3 }
== APP - checkout == Order passed: Order { OrderId = 3 }
== APP - order-processor == Order received : Order { orderId = 4 }
== APP - checkout == Order passed: Order { OrderId = 4 }
== APP - order-processor == Order received : Order { orderId = 5 }
== APP - checkout == Order passed: Order { OrderId = 5 }
== APP - order-processor == Order received : Order { orderId = 6 }
== APP - checkout == Order passed: Order { OrderId = 6 }
== APP - order-processor == Order received : Order { orderId = 7 }
== APP - checkout == Order passed: Order { OrderId = 7 }
== APP - order-processor == Order received : Order { orderId = 8 }
== APP - checkout == Order passed: Order { OrderId = 8 }
== APP - order-processor == Order received : Order { orderId = 9 }
== APP - checkout == Order passed: Order { OrderId = 9 }
== APP - order-processor == Order received : Order { orderId = 10 }
== APP - checkout == Order passed: Order { OrderId = 10 }
== APP - order-processor == Order received : Order { orderId = 11 }
== APP - checkout == Order passed: Order { OrderId = 11 }
== APP - order-processor == Order received : Order { orderId = 12 }
== APP - checkout == Order passed: Order { OrderId = 12 }
== APP - order-processor == Order received : Order { orderId = 13 }
== APP - checkout == Order passed: Order { OrderId = 13 }
== APP - order-processor == Order received : Order { orderId = 14 }
== APP - checkout == Order passed: Order { OrderId = 14 }
== APP - order-processor == Order received : Order { orderId = 15 }
== APP - checkout == Order passed: Order { OrderId = 15 }
== APP - order-processor == Order received : Order { orderId = 16 }
== APP - checkout == Order passed: Order { OrderId = 16 }
== APP - order-processor == Order received : Order { orderId = 17 }
== APP - checkout == Order passed: Order { OrderId = 17 }
== APP - order-processor == Order received : Order { orderId = 18 }
== APP - checkout == Order passed: Order { OrderId = 18 }
== APP - order-processor == Order received : Order { orderId = 19 }
== APP - checkout == Order passed: Order { OrderId = 19 }
== APP - order-processor == Order received : Order { orderId = 20 }
== APP - checkout == Order passed: Order { OrderId = 20 }
Exited App successfully

What happened?

Running dapr run -f . in this Quickstart started both the subscriber and publisher applications using the dapr.yaml Multi-App Run template file.

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
apps:
  - appDirPath: ./order-processor/
    appID: order-processor
    appPort: 8001
    command: ["python3", "app.py"]
  - appID: checkout
    appDirPath: ./checkout/
    command: ["python3", "app.py"]
order-processor service

The order-processor service receives the call from the checkout service:

@app.route('/orders', methods=['POST'])
def getOrder():
    data = request.json
    print('Order received : ' + json.dumps(data), flush=True)
    return json.dumps({'success': True}), 200, {
        'ContentType': 'application/json'}


app.run(port=8001)

checkout service

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

headers = {'dapr-app-id': 'order-processor'}

result = requests.post(
    url='%s/orders' % (base_url),
    data=json.dumps(order),
    headers=headers
)

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 Quickstart clone directory, navigate to the quickstart directory.

cd service_invocation/javascript/http

Install the dependencies for the order-processor and checkout apps:

cd ./order-processor
npm install
cd ../checkout
npm install
cd ..

Step 3: Run the order-processor and checkout services

With the following command, simultaneously run the following services alongside their own Dapr sidecars:

  • The order-processor service
  • The checkout service
dapr run -f .

Expected output

== APP - order-processor == Order received : Order { orderId = 1 }
== APP - checkout == Order passed: Order { OrderId = 1 }
== APP - order-processor == Order received : Order { orderId = 2 }
== APP - checkout == Order passed: Order { OrderId = 2 }
== APP - order-processor == Order received : Order { orderId = 3 }
== APP - checkout == Order passed: Order { OrderId = 3 }
== APP - order-processor == Order received : Order { orderId = 4 }
== APP - checkout == Order passed: Order { OrderId = 4 }
== APP - order-processor == Order received : Order { orderId = 5 }
== APP - checkout == Order passed: Order { OrderId = 5 }
== APP - order-processor == Order received : Order { orderId = 6 }
== APP - checkout == Order passed: Order { OrderId = 6 }
== APP - order-processor == Order received : Order { orderId = 7 }
== APP - checkout == Order passed: Order { OrderId = 7 }
== APP - order-processor == Order received : Order { orderId = 8 }
== APP - checkout == Order passed: Order { OrderId = 8 }
== APP - order-processor == Order received : Order { orderId = 9 }
== APP - checkout == Order passed: Order { OrderId = 9 }
== APP - order-processor == Order received : Order { orderId = 10 }
== APP - checkout == Order passed: Order { OrderId = 10 }
== APP - order-processor == Order received : Order { orderId = 11 }
== APP - checkout == Order passed: Order { OrderId = 11 }
== APP - order-processor == Order received : Order { orderId = 12 }
== APP - checkout == Order passed: Order { OrderId = 12 }
== APP - order-processor == Order received : Order { orderId = 13 }
== APP - checkout == Order passed: Order { OrderId = 13 }
== APP - order-processor == Order received : Order { orderId = 14 }
== APP - checkout == Order passed: Order { OrderId = 14 }
== APP - order-processor == Order received : Order { orderId = 15 }
== APP - checkout == Order passed: Order { OrderId = 15 }
== APP - order-processor == Order received : Order { orderId = 16 }
== APP - checkout == Order passed: Order { OrderId = 16 }
== APP - order-processor == Order received : Order { orderId = 17 }
== APP - checkout == Order passed: Order { OrderId = 17 }
== APP - order-processor == Order received : Order { orderId = 18 }
== APP - checkout == Order passed: Order { OrderId = 18 }
== APP - order-processor == Order received : Order { orderId = 19 }
== APP - checkout == Order passed: Order { OrderId = 19 }
== APP - order-processor == Order received : Order { orderId = 20 }
== APP - checkout == Order passed: Order { OrderId = 20 }
Exited App successfully

What happened?

Running dapr run -f . in this Quickstart started both the subscriber and publisher applications using the dapr.yaml Multi-App Run template file.

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
apps:
  - appDirPath: ./order-processor/
    appID: order-processor
    appPort: 5001
    command: ["npm", "start"]
  - appID: checkout
    appDirPath: ./checkout/
    command: ["npm", "start"]
order-processor service

The order-processor service receives the call from the checkout service:

app.post('/orders', (req, res) => {
    console.log("Order received:", req.body);
    res.sendStatus(200);
});
checkout service

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

let axiosConfig = {
  headers: {
      "dapr-app-id": "order-processor"
  }
};
const res = await axios.post(`${DAPR_HOST}:${DAPR_HTTP_PORT}/orders`, order , axiosConfig);
console.log("Order passed: " + res.config.data);

Step 1: Pre-requisites

For this example, you will need:

NOTE: .NET 6 is the minimally supported version of .NET for the Dapr .NET SDK packages in this release. Only .NET 8 and .NET 9 will be supported in Dapr v1.16 and later releases.

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 Quickstart clone directory, navigate to the quickstart directory.

cd service_invocation/csharp/http

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 order-processor and checkout services

With the following command, simultaneously run the following services alongside their own Dapr sidecars:

  • The order-processor service
  • The checkout service
dapr run -f .

Expected output

== APP - order-processor == Order received : Order { orderId = 1 }
== APP - checkout == Order passed: Order { OrderId = 1 }
== APP - order-processor == Order received : Order { orderId = 2 }
== APP - checkout == Order passed: Order { OrderId = 2 }
== APP - order-processor == Order received : Order { orderId = 3 }
== APP - checkout == Order passed: Order { OrderId = 3 }
== APP - order-processor == Order received : Order { orderId = 4 }
== APP - checkout == Order passed: Order { OrderId = 4 }
== APP - order-processor == Order received : Order { orderId = 5 }
== APP - checkout == Order passed: Order { OrderId = 5 }
== APP - order-processor == Order received : Order { orderId = 6 }
== APP - checkout == Order passed: Order { OrderId = 6 }
== APP - order-processor == Order received : Order { orderId = 7 }
== APP - checkout == Order passed: Order { OrderId = 7 }
== APP - order-processor == Order received : Order { orderId = 8 }
== APP - checkout == Order passed: Order { OrderId = 8 }
== APP - order-processor == Order received : Order { orderId = 9 }
== APP - checkout == Order passed: Order { OrderId = 9 }
== APP - order-processor == Order received : Order { orderId = 10 }
== APP - checkout == Order passed: Order { OrderId = 10 }
== APP - order-processor == Order received : Order { orderId = 11 }
== APP - checkout == Order passed: Order { OrderId = 11 }
== APP - order-processor == Order received : Order { orderId = 12 }
== APP - checkout == Order passed: Order { OrderId = 12 }
== APP - order-processor == Order received : Order { orderId = 13 }
== APP - checkout == Order passed: Order { OrderId = 13 }
== APP - order-processor == Order received : Order { orderId = 14 }
== APP - checkout == Order passed: Order { OrderId = 14 }
== APP - order-processor == Order received : Order { orderId = 15 }
== APP - checkout == Order passed: Order { OrderId = 15 }
== APP - order-processor == Order received : Order { orderId = 16 }
== APP - checkout == Order passed: Order { OrderId = 16 }
== APP - order-processor == Order received : Order { orderId = 17 }
== APP - checkout == Order passed: Order { OrderId = 17 }
== APP - order-processor == Order received : Order { orderId = 18 }
== APP - checkout == Order passed: Order { OrderId = 18 }
== APP - order-processor == Order received : Order { orderId = 19 }
== APP - checkout == Order passed: Order { OrderId = 19 }
== APP - order-processor == Order received : Order { orderId = 20 }
== APP - checkout == Order passed: Order { OrderId = 20 }
Exited App successfully

What happened?

Running dapr run -f . in this Quickstart started both the subscriber and publisher applications using the dapr.yaml Multi-App Run template file.

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
apps:
  - appDirPath: ./order-processor/
    appID: order-processor
    appPort: 7001
    command: ["dotnet", "run"]
  - appID: checkout
    appDirPath: ./checkout/
    command: ["dotnet", "run"]
order-processor service

The order-processor service receives the call from the checkout service:

app.MapPost("/orders", (Order order) =>
{
    Console.WriteLine("Order received : " + order);
    return order.ToString();
});
checkout service

In the Program.cs file for the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

var client = DaprClient.CreateInvokeHttpClient(appId: "order-processor");
var cts = new CancellationTokenSource();

var response = await client.PostAsJsonAsync("/orders", order, cts.Token);
Console.WriteLine("Order passed: " + 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 Quickstart clone directory, navigate to the quickstart directory.

cd service_invocation/java/http

Install the dependencies for the order-processor and checkout apps:

cd ./order-processor
mvn clean install
cd ../checkout
mvn clean install
cd ..

Step 3: Run the order-processor and checkout services

With the following command, simultaneously run the following services alongside their own Dapr sidecars:

  • The order-processor service
  • The checkout service
dapr run -f .

Expected output

== APP - order-processor == Order received : Order { orderId = 1 }
== APP - checkout == Order passed: Order { OrderId = 1 }
== APP - order-processor == Order received : Order { orderId = 2 }
== APP - checkout == Order passed: Order { OrderId = 2 }
== APP - order-processor == Order received : Order { orderId = 3 }
== APP - checkout == Order passed: Order { OrderId = 3 }
== APP - order-processor == Order received : Order { orderId = 4 }
== APP - checkout == Order passed: Order { OrderId = 4 }
== APP - order-processor == Order received : Order { orderId = 5 }
== APP - checkout == Order passed: Order { OrderId = 5 }
== APP - order-processor == Order received : Order { orderId = 6 }
== APP - checkout == Order passed: Order { OrderId = 6 }
== APP - order-processor == Order received : Order { orderId = 7 }
== APP - checkout == Order passed: Order { OrderId = 7 }
== APP - order-processor == Order received : Order { orderId = 8 }
== APP - checkout == Order passed: Order { OrderId = 8 }
== APP - order-processor == Order received : Order { orderId = 9 }
== APP - checkout == Order passed: Order { OrderId = 9 }
== APP - order-processor == Order received : Order { orderId = 10 }
== APP - checkout == Order passed: Order { OrderId = 10 }
== APP - order-processor == Order received : Order { orderId = 11 }
== APP - checkout == Order passed: Order { OrderId = 11 }
== APP - order-processor == Order received : Order { orderId = 12 }
== APP - checkout == Order passed: Order { OrderId = 12 }
== APP - order-processor == Order received : Order { orderId = 13 }
== APP - checkout == Order passed: Order { OrderId = 13 }
== APP - order-processor == Order received : Order { orderId = 14 }
== APP - checkout == Order passed: Order { OrderId = 14 }
== APP - order-processor == Order received : Order { orderId = 15 }
== APP - checkout == Order passed: Order { OrderId = 15 }
== APP - order-processor == Order received : Order { orderId = 16 }
== APP - checkout == Order passed: Order { OrderId = 16 }
== APP - order-processor == Order received : Order { orderId = 17 }
== APP - checkout == Order passed: Order { OrderId = 17 }
== APP - order-processor == Order received : Order { orderId = 18 }
== APP - checkout == Order passed: Order { OrderId = 18 }
== APP - order-processor == Order received : Order { orderId = 19 }
== APP - checkout == Order passed: Order { OrderId = 19 }
== APP - order-processor == Order received : Order { orderId = 20 }
== APP - checkout == Order passed: Order { OrderId = 20 }
Exited App successfully

What happened?

Running dapr run -f . in this Quickstart started both the subscriber and publisher applications using the dapr.yaml Multi-App Run template file.

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
apps:
  - appDirPath: ./order-processor/
    appID: order-processor
    appPort: 9001
    command: ["java", "-jar", "target/OrderProcessingService-0.0.1-SNAPSHOT.jar"]
  - appID: checkout
    appDirPath: ./checkout/
    command: ["java", "-jar", "target/CheckoutService-0.0.1-SNAPSHOT.jar"]
order-processor service

The order-processor service receives the call from the checkout service:

public String processOrders(@RequestBody Order body) {
        System.out.println("Order received: "+ body.getOrderId());
        return "CID" + body.getOrderId();
    }
checkout service

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

.header("Content-Type", "application/json")
.header("dapr-app-id", "order-processor")

HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("Order passed: "+ orderId)

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 Quickstart clone directory, navigate to the quickstart directory.

cd service_invocation/go/http

Install the dependencies for the order-processor and checkout apps:

cd ./order-processor
go build .
cd ../checkout
go build .
cd ..

Step 3: Run the order-processor and checkout services

With the following command, simultaneously run the following services alongside their own Dapr sidecars:

  • The order-processor service
  • The checkout service
dapr run -f .

Expected output

== APP - order-processor == Order received : Order { orderId = 1 }
== APP - checkout == Order passed: Order { OrderId = 1 }
== APP - order-processor == Order received : Order { orderId = 2 }
== APP - checkout == Order passed: Order { OrderId = 2 }
== APP - order-processor == Order received : Order { orderId = 3 }
== APP - checkout == Order passed: Order { OrderId = 3 }
== APP - order-processor == Order received : Order { orderId = 4 }
== APP - checkout == Order passed: Order { OrderId = 4 }
== APP - order-processor == Order received : Order { orderId = 5 }
== APP - checkout == Order passed: Order { OrderId = 5 }
== APP - order-processor == Order received : Order { orderId = 6 }
== APP - checkout == Order passed: Order { OrderId = 6 }
== APP - order-processor == Order received : Order { orderId = 7 }
== APP - checkout == Order passed: Order { OrderId = 7 }
== APP - order-processor == Order received : Order { orderId = 8 }
== APP - checkout == Order passed: Order { OrderId = 8 }
== APP - order-processor == Order received : Order { orderId = 9 }
== APP - checkout == Order passed: Order { OrderId = 9 }
== APP - order-processor == Order received : Order { orderId = 10 }
== APP - checkout == Order passed: Order { OrderId = 10 }
== APP - order-processor == Order received : Order { orderId = 11 }
== APP - checkout == Order passed: Order { OrderId = 11 }
== APP - order-processor == Order received : Order { orderId = 12 }
== APP - checkout == Order passed: Order { OrderId = 12 }
== APP - order-processor == Order received : Order { orderId = 13 }
== APP - checkout == Order passed: Order { OrderId = 13 }
== APP - order-processor == Order received : Order { orderId = 14 }
== APP - checkout == Order passed: Order { OrderId = 14 }
== APP - order-processor == Order received : Order { orderId = 15 }
== APP - checkout == Order passed: Order { OrderId = 15 }
== APP - order-processor == Order received : Order { orderId = 16 }
== APP - checkout == Order passed: Order { OrderId = 16 }
== APP - order-processor == Order received : Order { orderId = 17 }
== APP - checkout == Order passed: Order { OrderId = 17 }
== APP - order-processor == Order received : Order { orderId = 18 }
== APP - checkout == Order passed: Order { OrderId = 18 }
== APP - order-processor == Order received : Order { orderId = 19 }
== APP - checkout == Order passed: Order { OrderId = 19 }
== APP - order-processor == Order received : Order { orderId = 20 }
== APP - checkout == Order passed: Order { OrderId = 20 }
Exited App successfully

What happened?

Running dapr run -f . in this Quickstart started both the subscriber and publisher applications using the dapr.yaml Multi-App Run template file.

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
apps:
  - appDirPath: ./order-processor/
    appID: order-processor
    appPort: 6006
    command: ["go", "run", "."]
  - appID: checkout
    appDirPath: ./checkout/
    command: ["go", "run", "."]
order-processor service

In the order-processor service, each order is received via an HTTP POST request and processed by the getOrder function.

func getOrder(w http.ResponseWriter, r *http.Request) {
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Order received : %s", string(data))
}
checkout service

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

req.Header.Add("dapr-app-id", "order-processor")

response, err := client.Do(req)

Run one application at a time

Select your preferred language 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: Run order-processor service

In a terminal window, from the root of the Quickstart clone directory navigate to order-processor directory.

cd service_invocation/python/http/order-processor

Install the dependencies and build the application:

pip3 install -r requirements.txt

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 8001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- python3 app.py

Note: Since Python3.exe is not defined in Windows, you may need to use python app.py instead of python3 app.py.

@app.route('/orders', methods=['POST'])
def getOrder():
    data = request.json
    print('Order received : ' + json.dumps(data), flush=True)
    return json.dumps({'success': True}), 200, {
        'ContentType': 'application/json'}


app.run(port=8001)

Step 4: Run checkout service

In a new terminal window, from the root of the Quickstart clone directory navigate to the checkout directory.

cd service_invocation/python/http/checkout

Install the dependencies and build the application:

pip3 install -r requirements.txt

Run the checkout service alongside a Dapr sidecar.

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- python3 app.py

Note: Since Python3.exe is not defined in Windows, you may need to use python app.py instead of python3 app.py.

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

headers = {'dapr-app-id': 'order-processor'}

result = requests.post(
    url='%s/orders' % (base_url),
    data=json.dumps(order),
    headers=headers
)

Step 5: Use with Multi-App Run

You can run the Dapr applications in this quickstart with the Multi-App Run template. Instead of running two separate dapr run commands for the order-processor and checkout applications, run the following command:

dapr run -f .

To stop all applications, run:

dapr stop -f .

Step 6: View the Service Invocation outputs

Dapr invokes an application on any Dapr instance. In the code, the sidecar programming model encourages each application to talk to its own instance of Dapr. The Dapr instances then discover and communicate with one another.

checkout service output:

== APP == Order passed: {"orderId": 1}
== APP == Order passed: {"orderId": 2}
== APP == Order passed: {"orderId": 3}
== APP == Order passed: {"orderId": 4}
== APP == Order passed: {"orderId": 5}
== APP == Order passed: {"orderId": 6}
== APP == Order passed: {"orderId": 7}
== APP == Order passed: {"orderId": 8}
== APP == Order passed: {"orderId": 9}
== APP == Order passed: {"orderId": 10}

order-processor service output:

== APP == Order received: {"orderId": 1}
== APP == Order received: {"orderId": 2}
== APP == Order received: {"orderId": 3}
== APP == Order received: {"orderId": 4}
== APP == Order received: {"orderId": 5}
== APP == Order received: {"orderId": 6}
== APP == Order received: {"orderId": 7}
== APP == Order received: {"orderId": 8}
== APP == Order received: {"orderId": 9}
== APP == Order received: {"orderId": 10}

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: Run order-processor service

In a terminal window, from the root of the Quickstart clone directory navigate to order-processor directory.

cd service_invocation/javascript/http/order-processor

Install the dependencies:

npm install

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 5001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- npm start

app.post('/orders', (req, res) => {
    console.log("Order received:", req.body);
    res.sendStatus(200);
});

Step 4: Run checkout service

In a new terminal window, from the root of the Quickstart clone directory navigate to the checkout directory.

cd service_invocation/javascript/http/checkout

Install the dependencies:

npm install

Run the checkout service alongside a Dapr sidecar.

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- npm start

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

let axiosConfig = {
  headers: {
      "dapr-app-id": "order-processor"
  }
};
const res = await axios.post(`${DAPR_HOST}:${DAPR_HTTP_PORT}/orders`, order , axiosConfig);
console.log("Order passed: " + res.config.data);

Step 5: Use with Multi-App Run

You can run the Dapr applications in this quickstart with the Multi-App Run template. Instead of running two separate dapr run commands for the order-processor and checkout applications, run the following command:

dapr run -f .

To stop all applications, run:

dapr stop -f .

Step 6: View the Service Invocation outputs

Dapr invokes an application on any Dapr instance. In the code, the sidecar programming model encourages each application to talk to its own instance of Dapr. The Dapr instances then discover and communicate with one another.

checkout service output:

== APP == Order passed: {"orderId": 1}
== APP == Order passed: {"orderId": 2}
== APP == Order passed: {"orderId": 3}
== APP == Order passed: {"orderId": 4}
== APP == Order passed: {"orderId": 5}
== APP == Order passed: {"orderId": 6}
== APP == Order passed: {"orderId": 7}
== APP == Order passed: {"orderId": 8}
== APP == Order passed: {"orderId": 9}
== APP == Order passed: {"orderId": 10}

order-processor service output:

== APP == Order received: {"orderId": 1}
== APP == Order received: {"orderId": 2}
== APP == Order received: {"orderId": 3}
== APP == Order received: {"orderId": 4}
== APP == Order received: {"orderId": 5}
== APP == Order received: {"orderId": 6}
== APP == Order received: {"orderId": 7}
== APP == Order received: {"orderId": 8}
== APP == Order received: {"orderId": 9}
== APP == Order received: {"orderId": 10}

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: Run order-processor service

In a terminal window, from the root of the Quickstart clone directory navigate to order-processor directory.

cd service_invocation/csharp/http/order-processor

Install the dependencies:

dotnet restore
dotnet build

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 7001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- dotnet run

Below is the working code block from the order processor’s Program.cs file.

app.MapPost("/orders", (Order order) =>
{
    Console.WriteLine("Order received : " + order);
    return order.ToString();
});

Step 4: Run checkout service

In a new terminal window, from the root of the Quickstart clone directory navigate to the checkout directory.

cd service_invocation/csharp/http/checkout

Install the dependencies:

dotnet restore
dotnet build

Run the checkout service alongside a Dapr sidecar.

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- dotnet run

In the Program.cs file for the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

var client = DaprClient.CreateInvokeHttpClient(appId: "order-processor");
var cts = new CancellationTokenSource();

var response = await client.PostAsJsonAsync("/orders", order, cts.Token);
Console.WriteLine("Order passed: " + order);

Step 5: Use with Multi-App Run

You can run the Dapr applications in this quickstart with the Multi-App Run template. Instead of running two separate dapr run commands for the order-processor and checkout applications, run the following command:

dapr run -f .

To stop all applications, run:

dapr stop -f .

Step 6: View the Service Invocation outputs

Dapr invokes an application on any Dapr instance. In the code, the sidecar programming model encourages each application to talk to its own instance of Dapr. The Dapr instances then discover and communicate with one another.

checkout service output:

== APP == Order passed: Order { OrderId: 1 }
== APP == Order passed: Order { OrderId: 2 }
== APP == Order passed: Order { OrderId: 3 }
== APP == Order passed: Order { OrderId: 4 }
== APP == Order passed: Order { OrderId: 5 }
== APP == Order passed: Order { OrderId: 6 }
== APP == Order passed: Order { OrderId: 7 }
== APP == Order passed: Order { OrderId: 8 }
== APP == Order passed: Order { OrderId: 9 }
== APP == Order passed: Order { OrderId: 10 }

order-processor service output:

== APP == Order received: Order { OrderId: 1 }
== APP == Order received: Order { OrderId: 2 }
== APP == Order received: Order { OrderId: 3 }
== APP == Order received: Order { OrderId: 4 }
== APP == Order received: Order { OrderId: 5 }
== APP == Order received: Order { OrderId: 6 }
== APP == Order received: Order { OrderId: 7 }
== APP == Order received: Order { OrderId: 8 }
== APP == Order received: Order { OrderId: 9 }
== APP == Order received: Order { OrderId: 10 }

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: Run order-processor service

In a terminal window, from the root of the Quickstart clone directory navigate to order-processor directory.

cd service_invocation/java/http/order-processor

Install the dependencies:

mvn clean install

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-id order-processor --app-port 9001 --app-protocol http --dapr-http-port 3501 -- java -jar target/OrderProcessingService-0.0.1-SNAPSHOT.jar

public String processOrders(@RequestBody Order body) {
        System.out.println("Order received: "+ body.getOrderId());
        return "CID" + body.getOrderId();
    }

Step 4: Run checkout service

In a new terminal window, from the root of the Quickstart clone directory navigate to the checkout directory.

cd service_invocation/java/http/checkout

Install the dependencies:

mvn clean install

Run the checkout service alongside a Dapr sidecar.

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- java -jar target/CheckoutService-0.0.1-SNAPSHOT.jar

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

.header("Content-Type", "application/json")
.header("dapr-app-id", "order-processor")

HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println("Order passed: "+ orderId)

Step 5: Use with Multi-App Run

You can run the Dapr applications in this quickstart with the Multi-App Run template. Instead of running two separate dapr run commands for the order-processor and checkout applications, run the following command:

dapr run -f .

To stop all applications, run:

dapr stop -f .

Step 6: View the Service Invocation outputs

Dapr invokes an application on any Dapr instance. In the code, the sidecar programming model encourages each application to talk to its own instance of Dapr. The Dapr instances then discover and communicate with one another.

checkout service output:

== APP == Order passed: 1
== APP == Order passed: 2
== APP == Order passed: 3
== APP == Order passed: 4
== APP == Order passed: 5
== APP == Order passed: 6
== APP == Order passed: 7
== APP == Order passed: 8
== APP == Order passed: 9
== APP == Order passed: 10

order-processor service output:

== APP == Order received: 1
== APP == Order received: 2
== APP == Order received: 3
== APP == Order received: 4
== APP == Order received: 5
== APP == Order received: 6
== APP == Order received: 7
== APP == Order received: 8
== APP == Order received: 9
== APP == Order received: 10

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: Run order-processor service

In a terminal window, from the root of the Quickstart clone directory navigate to order-processor directory.

cd service_invocation/go/http/order-processor

Install the dependencies:

go build .

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 6006 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- go run .

Each order is received via an HTTP POST request and processed by the getOrder function.

func getOrder(w http.ResponseWriter, r *http.Request) {
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Order received : %s", string(data))
}

Step 4: Run checkout service

In a new terminal window, from the root of the Quickstart clone directory navigate to the checkout directory.

cd service_invocation/go/http/checkout

Install the dependencies:

go build .

Run the checkout service alongside a Dapr sidecar.

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- go run .

In the checkout service, you’ll notice there’s no need to rewrite your app code to use Dapr’s service invocation. You can enable service invocation by simply adding the dapr-app-id header, which specifies the ID of the target service.

req.Header.Add("dapr-app-id", "order-processor")

response, err := client.Do(req)

Step 5: Use with Multi-App Run

You can run the Dapr applications in this quickstart with the Multi-App Run template. Instead of running two separate dapr run commands for the order-processor and checkout applications, run the following command:

dapr run -f .

To stop all applications, run:

dapr stop -f .

Step 6: View the Service Invocation outputs

Dapr invokes an application on any Dapr instance. In the code, the sidecar programming model encourages each application to talk to its own instance of Dapr. The Dapr instances then discover and communicate with one another.

checkout service output:

== APP == Order passed:  {"orderId":1}
== APP == Order passed:  {"orderId":2}
== APP == Order passed:  {"orderId":3}
== APP == Order passed:  {"orderId":4}
== APP == Order passed:  {"orderId":5}
== APP == Order passed:  {"orderId":6}
== APP == Order passed:  {"orderId":7}
== APP == Order passed:  {"orderId":8}
== APP == Order passed:  {"orderId":9}
== APP == Order passed:  {"orderId":10}

order-processor service output:

== APP == Order received :  {"orderId":1}
== APP == Order received :  {"orderId":2}
== APP == Order received :  {"orderId":3}
== APP == Order received :  {"orderId":4}
== APP == Order received :  {"orderId":5}
== APP == Order received :  {"orderId":6}
== APP == Order received :  {"orderId":7}
== APP == Order received :  {"orderId":8}
== APP == Order received :  {"orderId":9}
== APP == Order received :  {"orderId":10}

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

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Last modified July 18, 2025: Upgrade hugo docsy into 1.16 (#4733) (b2fdd345)