docs/daprdocs/content/en/getting-started/quickstarts/serviceinvocation-quickstart.md

type	title	linkTitle	weight	description
docs	Quickstart: Service Invocation	Service Invocation	70	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.

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.

Learn more about Dapr's methods for service invocation in the [overview article]({{< ref service-invocation-overview.md >}}).

Select your preferred language before proceeding with the quickstart.

{{< tabs "Python" "JavaScript" ".NET" "Java" "Go" >}}

{{% codetab %}}

Pre-requisites

For this example, you will need:

• Dapr CLI and initialized environment.
• Python 3.7+ installed.

• Docker Desktop

Step 1: Set up the environment

Clone the sample we've provided.

git clone https://github.com/dapr/quickstarts.git

Run checkout service

In a terminal window, navigate to the checkout directory.

cd service_invocation/python/http/checkout

Install the dependencies:

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

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
)

Run order-processor service

In a new terminal window, navigate to order-processor directory.

cd service_invocation/python/http/order-processor

Install the dependencies:

pip3 install -r requirements.txt 

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 6001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- 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=5001)

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}

{{% /codetab %}}

{{% codetab %}}

Pre-requisites

For this example, you will need:

• Dapr CLI and initialized environment.
• Latest Node.js installed.

• Docker Desktop

Step 1: Set up the environment

Clone the sample we've provided.

git clone https://github.com/dapr/quickstarts.git

Run checkout service

In a terminal window, 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);

Run order-processor service

In a new terminal window, 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 6001 --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);
});

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}

{{% /codetab %}}

{{% codetab %}}

Pre-requisites

For this example, you will need:

• Dapr CLI and initialized environment.
• .NET SDK or .NET 6 SDK installed.

• Docker Desktop

Step 1: Set up the environment

Clone the sample we've provided.

git clone https://github.com/dapr/quickstarts.git

Run checkout service

In a terminal window, 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 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 = new HttpClient();
client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

client.DefaultRequestHeaders.Add("dapr-app-id", "order-processor");

var response = await client.PostAsync($"{baseURL}/orders", content);
    Console.WriteLine("Order passed: " + order);

Run order-processor service

In a new terminal window, 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

app.MapPost("/orders", async context => {
    var data = await context.Request.ReadFromJsonAsync<Order>();
    Console.WriteLine("Order received : " + data);
    await context.Response.WriteAsync(data.ToString());
});

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 }

{{% /codetab %}}

{{% codetab %}}

Pre-requisites

For this example, you will need:

• Dapr CLI and initialized environment.
• Java JDK 11 (or greater):
  • Oracle JDK, or
  • OpenJDK
• Apache Maven, version 3.x.

• Docker Desktop

Step 1: Set up the environment

Clone the sample we've provided.

git clone https://github.com/dapr/quickstarts.git

Run checkout service

In a terminal window, 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)

Run order-processor service

In a new terminal window, 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 6001 --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();
    }

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

{{% /codetab %}}

{{% codetab %}}

Pre-requisites

For this example, you will need:

• Dapr CLI and initialized environment.
• Latest version of Go.

• Docker Desktop

Step 1: Set up the environment

Clone the sample we've provided.

git clone https://github.com/dapr/quickstarts.git

Run checkout service

In a terminal window, navigate to the checkout directory.

cd service_invocation/go/http/checkout

Install the dependencies:

go build app.go

Run the checkout service alongside a Dapr sidecar.

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

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)

if err != nil {
			fmt.Print(err.Error())
			os.Exit(1)
		}

		result, err := ioutil.ReadAll(response.Body)
		if err != nil {
			log.Fatal(err)
		}

		log.Println("Order passed: ", string(result))

Run order-processor service

In a new terminal window, navigate to order-processor directory.

cd service_invocation/go/http/order-processor

Install the dependencies:

go build app.go

Run the order-processor service alongside a Dapr sidecar.

dapr run --app-port 6001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- go run app.go

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))

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}

{{% /codetab %}}

{{% /tabs %}}

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

• Learn more about [Service Invocation as a Dapr building block]({{< ref service-invocation-overview.md >}})
• Learn more about how to invoke Dapr's Service Invocation with:
  • [HTTP]({{< ref howto-invoke-discover-services.md >}}), or
  • [gRPC]({{< ref howto-invoke-services-grpc.md >}})

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