Tutorial: Microservices communication using Dapr Publish and Subscribe

In this tutorial, you create publisher and subscriber microservices that leverage the Dapr Pub/sub API to communicate using messages for event-driven architectures. You'll:

• Create a publisher microservice and a subscriber microservice that leverage the Dapr pub/sub API to communicate using messages for event-driven architectures.
• Deploy the application to Azure Container Apps via the Azure Developer CLI with provided Bicep.

The sample pub/sub project includes:

1. A message generator checkout service (publisher) that generates messages of a specific topic.
2. An order-processor service (subscriber) that listens for messages from the checkout service of a specific topic.

Prerequisites

• Install Azure Developer CLI
• Install and init Dapr
• Docker Desktop
• Install Git

Run the Node.js applications locally

Before deploying the application to Azure Container Apps, run the order-processor and checkout services locally with Dapr and Azure Service Bus.

Prepare the project

1. Clone the sample application to your local machine.

   git clone https://github.com/Azure-Samples/pubsub-dapr-nodejs-servicebus.git
   

2. Navigate into the sample's root directory.

   cd pubsub-dapr-nodejs-servicebus
   

Run the applications using the Dapr CLI

Start by running the order-processor subscriber service.

1. From the sample's root directory, change directories to order-processor.

   cd order-processor
   

2. Install the dependencies.

   npm install
   

3. Run the order-processor service.

   dapr run --app-port 5001 --app-id order-processing --app-protocol http --dapr-http-port 3501 --resources-path ../components -- npm run start
   

4. In a new terminal window, from the sample's root directory, navigate to the checkout publisher service.

   cd checkout
   

5. Install the dependencies.

   npm install
   

6. Run the checkout service.

   dapr run --app-id checkout --app-protocol http --resources-path ../components -- npm run start
   

   Expected output

   In both terminals, the checkout service publishes 10 messages received by the order-processor service before exiting.

   checkout 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}
   

   order-processor 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}
   

7. Make sure both applications have stopped by running the following commands. In the checkout terminal:

   dapr stop --app-id checkout
   

   In the order-processor terminal:

   dapr stop --app-id order-processor
   

Deploy the application template using Azure Developer CLI

Deploy the application to Azure Container Apps using azd.

Prepare the project

In a new terminal window, navigate into the sample's root directory.

cd pubsub-dapr-nodejs-servicebus

Provision and deploy using Azure Developer CLI

1. Run azd init to initialize the project.

   azd init
   

2. When prompted in the terminal, provide the following parameters.

   Parameter	Description
   Environment Name	Prefix for the resource group created to hold all Azure resources.
   Azure Location	The Azure location for your resources.
   Azure Subscription	The Azure subscription for your resources.

3. Run azd up to provision the infrastructure and deploy the application to Azure Container Apps in a single command.

   azd up
   

   This process may take some time to complete. As the azd up command completes, the CLI output displays two Azure portal links to monitor the deployment progress. The output also demonstrates how azd up:

   • Creates and configures all necessary Azure resources via the provided Bicep files in the ./infra directory using azd provision. Once provisioned by Azure Developer CLI, you can access these resources via the Azure portal. The files that provision the Azure resources include:
     • main.parameters.json
     • main.bicep
     • An app resources directory organized by functionality
     • A core reference library that contains the Bicep modules used by the azd template
   • Deploys the code using azd deploy

   Expected output

   Initializing a new project (azd init)
   
   
   Provisioning Azure resources (azd provision)
   Provisioning Azure resources can take some time
   
     You can view detailed progress in the Azure Portal:
     https://portal.azure.com
   
     (✓) Done: Resource group: resource-group-name
     (✓) Done: Application Insights: app-insights-name
     (✓) Done: Portal dashboard: portal-dashboard-name
     (✓) Done: Log Analytics workspace: log-analytics-name
     (✓) Done: Key vault: key-vault-name
     (✓) Done: Container Apps Environment: ca-env-name
     (✓) Done: Container App: ca-checkout-name
     (✓) Done: Container App: ca-orders-name
   
   
   Deploying services (azd deploy)
   
     (✓) Done: Deploying service checkout
     (✓) Done: Deploying service orders
     - Endpoint: https://ca-orders-name.endpoint.region.azurecontainerapps.io/
   
   SUCCESS: Your Azure app has been deployed!
   You can view the resources created under the resource group resource-group-name in Azure Portal:
   https://portal.azure.com/#@/resource/subscriptions/subscription-id/resourceGroups/resource-group-name/overview
   

Confirm successful deployment

In the Azure portal, verify the checkout service is publishing messages to the Azure Service Bus topic.

1. Copy the checkout container app name from the terminal output.

2. Sign in to the Azure portal and search for the container app resource by name.

3. In the Container Apps dashboard, select Monitoring > Log stream.

   

4. Confirm the checkout container is logging the same output as in the terminal earlier.

   

5. Do the same for the order-processor service.

   

What happened?

Upon successful completion of the azd up command:

• Azure Developer CLI provisioned the Azure resources referenced in the sample project's ./infra directory to the Azure subscription you specified. You can now view those Azure resources via the Azure portal.
• The app deployed to Azure Container Apps. From the portal, you can browse to the fully functional app.

Run the Python applications locally

Before deploying the application to Azure Container Apps, run the order-processor and checkout services locally with Dapr and Azure Service Bus.

Prepare the project

1. Clone the sample application to your local machine.

   git clone https://github.com/Azure-Samples/pubsub-dapr-python-servicebus.git
   

2. Navigate into the sample's root directory.

   cd pubsub-dapr-python-servicebus
   

Run the applications using the Dapr CLI

Start by running the order-processor subscriber service.

1. From the sample's root directory, change directories to order-processor.

   cd order-processor
   

2. Install the dependencies.

   pip3 install -r requirements.txt
   

3. Run the order-processor service.

   Windows

   dapr run --app-id order-processor --resources-path ../components/ --app-port 5001 -- python app.py
   

   Linux

   dapr run --app-id order-processor --resources-path ../components/ --app-port 5001 -- python3 app.py
   

---

1. In a new terminal window, from the sample's root directory, navigate to the checkout publisher service.

   cd checkout
   

2. Install the dependencies.

   pip3 install -r requirements.txt
   

3. Run the checkout service.

   Windows

   dapr run --app-id checkout --resources-path ../components/ -- python app.py
   

   Linux

   dapr run --app-id checkout --resources-path ../components/ -- python3 app.py
   

---

Expected output

In both terminals, the checkout service publishes 10 messages received by the order-processor service before exiting.

checkout 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}

order-processor 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}

1. Make sure both applications have stopped by running the following commands. In the checkout terminal:

   dapr stop --app-id checkout
   

   In the order-processor terminal:

   dapr stop --app-id order-processor
   

Deploy the application template using Azure Developer CLI

Deploy the application to Azure Container Apps using azd.

Prepare the project

In a new terminal window, navigate into the sample's root directory.

cd pubsub-dapr-python-servicebus

Provision and deploy using Azure Developer CLI

1. Run azd init to initialize the project.

   azd init
   

2. When prompted in the terminal, provide the following parameters.

   Parameter	Description
   Environment Name	Prefix for the resource group created to hold all Azure resources.
   Azure Location	The Azure location for your resources.
   Azure Subscription	The Azure subscription for your resources.

3. Run azd up to provision the infrastructure and deploy the application to Azure Container Apps in a single command.

   azd up
   

   This process may take some time to complete. As the azd up command completes, the CLI output displays two Azure portal links to monitor the deployment progress. The output also demonstrates how azd up:

   • Creates and configures all necessary Azure resources via the provided Bicep files in the ./infra directory using azd provision. Once provisioned by Azure Developer CLI, you can access these resources via the Azure portal. The files that provision the Azure resources include:
     • main.parameters.json
     • main.bicep
     • An app resources directory organized by functionality
     • A core reference library that contains the Bicep modules used by the azd template
   • Deploys the code using azd deploy

   Expected output

   Initializing a new project (azd init)
   
   
   Provisioning Azure resources (azd provision)
   Provisioning Azure resources can take some time
   
     You can view detailed progress in the Azure Portal:
     https://portal.azure.com
   
     (✓) Done: Resource group: resource-group-name
     (✓) Done: Application Insights: app-insights-name
     (✓) Done: Portal dashboard: portal-dashboard-name
     (✓) Done: Log Analytics workspace: log-analytics-name
     (✓) Done: Key vault: key-vault-name
     (✓) Done: Container Apps Environment: ca-env-name
     (✓) Done: Container App: ca-checkout-name
     (✓) Done: Container App: ca-orders-name
   
   
   Deploying services (azd deploy)
   
     (✓) Done: Deploying service checkout
     (✓) Done: Deploying service orders
     - Endpoint: https://ca-orders-name.endpoint.region.azurecontainerapps.io/
   
   SUCCESS: Your Azure app has been deployed!
   You can view the resources created under the resource group resource-group-name in Azure Portal:
   https://portal.azure.com/#@/resource/subscriptions/subscription-id/resourceGroups/resource-group-name/overview
   

Confirm successful deployment

In the Azure portal, verify the checkout service is publishing messages to the Azure Service Bus topic.

1. Copy the checkout container app name from the terminal output.

2. Sign in to the Azure portal and search for the container app resource by name.

3. In the Container Apps dashboard, select Monitoring > Log stream.

   

4. Confirm the checkout container is logging the same output as in the terminal earlier.

   

5. Do the same for the order-processor service.

   

What happened?

Upon successful completion of the azd up command:

• Azure Developer CLI provisioned the Azure resources referenced in the sample project's ./infra directory to the Azure subscription you specified. You can now view those Azure resources via the Azure portal.
• The app deployed to Azure Container Apps. From the portal, you can browse to the fully functional app.

Run the .NET applications locally

Before deploying the application to Azure Container Apps, run the order-processor and checkout services locally with Dapr and Azure Service Bus.

Prepare the project

1. Clone the sample application to your local machine.

   git clone https://github.com/Azure-Samples/pubsub-dapr-csharp-servicebus.git
   

2. Navigate into the sample's root directory.

   cd pubsub-dapr-csharp-servicebus
   

Run the applications using the Dapr CLI

Start by running the order-processor subscriber service

1. From the sample's root directory, change directories to order-processor.

   cd order-processor
   

2. Install the dependencies.

   dotnet build
   

3. Run the order-processor service.

   dapr run --app-id order-processor --resources-path ../components/ --app-port 7001 -- dotnet run --project .
   

4. In a new terminal window, from the sample's root directory, navigate to the checkout publisher service.

   cd checkout
   

5. Install the dependencies.

   dotnet build
   

6. Run the checkout service.

   dapr run --app-id checkout --resources-path ../components/ -- dotnet run --project .
   

   Expected output

   In both terminals, the checkout service publishes 10 messages received by the order-processor service before exiting.

   checkout 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}
   

   order-processor 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}
   

7. Make sure both applications have stopped by running the following commands. In the checkout terminal.

   dapr stop --app-id checkout
   

   In the order-processor terminal:

   dapr stop --app-id order-processor
   

Deploy the application template using Azure Developer CLI

Deploy the application to Azure Container Apps using azd.

Prepare the project

In a new terminal window, navigate into the sample's root directory.

cd pubsub-dapr-csharp-servicebus

Provision and deploy using Azure Developer CLI

1. Run azd init to initialize the project.

   azd init
   

2. When prompted in the terminal, provide the following parameters.

   Parameter	Description
   Environment Name	Prefix for the resource group created to hold all Azure resources.
   Azure Location	The Azure location for your resources.
   Azure Subscription	The Azure subscription for your resources.

3. Run azd up to provision the infrastructure and deploy the application to Azure Container Apps in a single command.

   azd up
   

   This process may take some time to complete. As the azd up command completes, the CLI output displays two Azure portal links to monitor the deployment progress. The output also demonstrates how azd up:

   • Creates and configures all necessary Azure resources via the provided Bicep files in the ./infra directory using azd provision. Once provisioned by Azure Developer CLI, you can access these resources via the Azure portal. The files that provision the Azure resources include:
     • main.parameters.json
     • main.bicep
     • An app resources directory organized by functionality
     • A core reference library that contains the Bicep modules used by the azd template
   • Deploys the code using azd deploy

   Expected output

   Initializing a new project (azd init)
   
   
   Provisioning Azure resources (azd provision)
   Provisioning Azure resources can take some time
   
     You can view detailed progress in the Azure Portal:
     https://portal.azure.com
   
     (✓) Done: Resource group: resource-group-name
     (✓) Done: Application Insights: app-insights-name
     (✓) Done: Portal dashboard: portal-dashboard-name
     (✓) Done: Log Analytics workspace: log-analytics-name
     (✓) Done: Key vault: key-vault-name
     (✓) Done: Container Apps Environment: ca-env-name
     (✓) Done: Container App: ca-checkout-name
     (✓) Done: Container App: ca-orders-name
   
   
   Deploying services (azd deploy)
   
     (✓) Done: Deploying service checkout
     (✓) Done: Deploying service orders
     - Endpoint: https://ca-orders-name.endpoint.region.azurecontainerapps.io/
   
   SUCCESS: Your Azure app has been deployed!
   You can view the resources created under the resource group resource-group-name in Azure Portal:
   https://portal.azure.com/#@/resource/subscriptions/subscription-id/resourceGroups/resource-group-name/overview
   

Confirm successful deployment

In the Azure portal, verify the checkout service is publishing messages to the Azure Service Bus topic.

1. Copy the checkout container app name from the terminal output.

2. Sign in to the Azure portal and search for the container app resource by name.

3. In the Container Apps dashboard, select Monitoring > Log stream.

   

4. Confirm the checkout container is logging the same output as in the terminal earlier.

   

5. Do the same for the order-processor service.

   

What happened?

Upon successful completion of the azd up command:

• Azure Developer CLI provisioned the Azure resources referenced in the sample project's ./infra directory to the Azure subscription you specified. You can now view those Azure resources via the Azure portal.
• The app deployed to Azure Container Apps. From the portal, you can browse to the fully functional app.

Clean up resources

If you're not going to continue to use this application, delete the Azure resources you've provisioned with the following command:

azd down

Next steps

• Learn more about deploying applications to Azure Container Apps.
• Enable token authentication for Dapr requests.
• Learn more about Azure Developer CLI and making your applications compatible with azd.
• Scale your applications using KEDA scalers