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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.

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

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

Run the multi app run template:

dapr run -f .

The terminal console output should look similar to this:

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

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 .. -- python3 app.py commands. This next section covers how to do this.

Run Python order-processor with Dapr

Install dependencies for order-processor app:

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

Run the Python order-processor app with Dapr:

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

Run Python checkout with Dapr

Open a new terminal window and install dependencies for checkout app:

cd ./checkout
pip3 install -r requirements.txt

Run the Python checkout app with Dapr:

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

Stop and clean up application processes

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

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