Tutorial: Microservices communication using Dapr Publish and Subscribe

  • Article

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.

Diagram of the pub/sub sample.

Prerequisites

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.cn

  (✓) 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.dev/

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.cn/#@/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.

    Screenshot of navigating to the Log stream page in the Azure portal.

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

    Screenshot of the checkout service container's log stream in the Azure portal.

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

    Screenshot of the order processor service container's log stream in the Azure portal.

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.

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

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

    cd checkout

  5. Install the dependencies.

    pip3 install -r requirements.txt

  6. Run the checkout service.

    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}

  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-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.cn

  (✓) 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.dev/

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.cn/#@/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.

    Screenshot of navigating to the Log stream page in the Azure portal.

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

    Screenshot of the checkout service container's log stream in the Azure portal.

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

    Screenshot of the order processor service container's log stream in the Azure portal.

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.cn

  (✓) 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.dev.cn/

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.cn/#@/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.

    Screenshot of navigating to the Log stream page in the Azure portal.

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

    Screenshot of the checkout service container's log stream in the Azure portal.

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

    Screenshot of the order processor service container's log stream in the Azure portal.

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