Service Invocation

In this quickstart, you'll create a checkout service and an order processor service to demonstrate how to use the service invocation API. The checkout service uses Dapr's http proxying capability to invoke a method on the order processing service.

Visit this link for more information about Dapr and service invocation.

This quickstart includes one checkout service:

• Python client service checkout

And one order processor service:

• Python order-processor service order-processor

Run all apps with multi-app run template file:

This section shows how to run both applications at once using multi-app run template files with dapr run -f .. This enables to you test the interactions between multiple applications.

1. Open a new terminal window and install dependencies for order-processor and checkout apps:

uv sync --all-packages

2. Run the multi app run template:

uv run dapr run -f .

The terminal console output should look similar to this:

Order received : {"orderId": 1}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 1}
Order received : {"orderId": 2}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 2}
Order received : {"orderId": 3}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 3}
Order received : {"orderId": 4}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 4}
Order received : {"orderId": 5}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 5}
Order received : {"orderId": 6}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 6}
Order received : {"orderId": 7}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 7}
Order received : {"orderId": 8}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 8}
Order received : {"orderId": 9}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 9}
Order received : {"orderId": 10}
127.0.0.1 - - [DATE] "POST /orders HTTP/1.1" 200 -
Order passed: {"orderId": 10}

3. Stop and clean up application processes

dapr stop -f .

Run a single app at a time with Dapr (Optional)

An alternative to running all or multiple applications at once is to run single apps one-at-a-time using multiple dapr run .. -- uv run python app.py commands. This next section covers how to do this.

Run Python order-processor with Dapr

1. Install dependencies:

uv sync --all-packages

2. Run the Python order-processor app with Dapr:

cd ./order-processor
dapr run --app-port 8001 --app-id order-processor --app-protocol http --dapr-http-port 3501 -- uv run python app.py

Run Python checkout with Dapr

1. Open a new terminal window. Dependencies are shared with order-processor (already installed via uv sync --all-packages above).

2. Run the Python checkout app with Dapr:

cd ./checkout
dapr run  --app-id checkout --app-protocol http --dapr-http-port 3500 -- uv run python app.py

Stop and clean up application processes

dapr stop --app-id checkout
dapr stop --app-id order-processor