quickstarts/service_invocation/java/http

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:

• Java client service checkout

And one order processor service:

• Java order-processor service order-processor

Pre-requisites

• Dapr and Dapr Cli.
• Java JDK 17 (or greater):
  • Microsoft JDK 17
  • Oracle JDK 17
  • OpenJDK 17
• Apache Maven version 3.x.

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:

cd ./order-processor
mvn clean install
cd ../checkout
mvn clean install
cd ..

2. Run the multi app run template:

dapr run -f .

The terminal console output should look similar to this:

== APP - order-processor == Order received: 1
== APP - checkout == Order passed: 1
== APP - order-processor == Order received: 2
== APP - checkout == Order passed: 2
== APP - order-processor == Order received: 3
== APP - checkout == Order passed: 3
== APP - order-processor == Order received: 4
== APP - checkout == Order passed: 4
== APP - order-processor == Order received: 5
== APP - checkout == Order passed: 5
== APP - order-processor == Order received: 6
== APP - checkout == Order passed: 6
== APP - order-processor == Order received: 7
== APP - checkout == Order passed: 7
== APP - order-processor == Order received: 8
== APP - checkout == Order passed: 8
== APP - order-processor == Order received: 9
== APP - checkout == Order passed: 9
== APP - order-processor == Order received: 10
== APP - checkout == Order passed: 10
== APP - order-processor == Order received: 11
== APP - checkout == Order passed: 11
== APP - order-processor == Order received: 12
== APP - checkout == Order passed: 12

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 .. -- java -jar commands. This next section covers how to do this.

Run Java order-processor with Dapr

1. Open a new terminal window and navigate to order-processor directory and install dependencies:

cd ./order-processor
mvn clean install

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

dapr run --app-id order-processor --app-port 9001 --app-protocol http --dapr-http-port 3501 -- java -jar target/OrderProcessingService-0.0.1-SNAPSHOT.jar

Run Java checkout service with Dapr

1. Open a new terminal window and navigate to checkout directory and install dependencies:

cd ./checkout
mvn clean install

2. Run the Java checkout app with Dapr:

dapr run --app-id checkout --app-protocol http --dapr-http-port 3500 -- java -jar target/CheckoutService-0.0.1-SNAPSHOT.jar

Stop and clean up application processes

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