Temperature Conversion Service

Description

This example contains a workflow that performs two consecutive REST invocations defined as functions.
The workflow is described using JSON format as defined in the CNCF Serverless Workflow specification.

The workflow expects a JSON input containing the temperature in Fahrenheits:

{
  "fahrenheit": 100
}

The workflow starts defining the constants to be used during the computation. Then it will call a sequence of REST functions to solve the equation: Celsius = (Fahrenheit - 32) * 0.5553. Finally, the result will be returned to the caller, the final product of the equation is the temperature converted to Celsius.

Installing and Running

Prerequisites

You will need:

• Java 11+ installed
• Environment variable JAVA_HOME set accordingly
• Maven 3.8.6+ installed

When using native image compilation, you will also need:

• GraalVm 20.2.0+ installed
• Environment variable GRAALVM_HOME set accordingly
• Note that GraalVM native image compilation typically requires other packages (glibc-devel, zlib-devel and gcc) to be installed too. You also need ‘native-image’ installed in GraalVM (using ‘gu install native-image’). Please refer to GraalVM installation documentation for more details.

Compile and Run in Local Dev Mode

mvn clean package quarkus:dev

Compile and Run in JVM mode

mvn clean package 
java -jar target/quarkus-app/quarkus-run.jar

or on Windows

mvn clean package
java -jar target\quarkus-app\quarkus-run.jar

Compile and Run using Local Native Image

Note that this requires GRAALVM_HOME to point to a valid GraalVM installation

mvn clean package -Pnative

To run the generated native executable, generated in target/, execute

./target/conversion-workflow-runner

Submit a request

Before submitting a request, run the Subtraction and Multiplication on separate terminals on ports 8181 and 8282 respectively (use the property quarkus.http.port).

The service based on the JSON workflow definition can be access by sending a POST request to http://localhost:8080/fahrenheit_to_celsius with the following content:

{
  "workflowdata": {
    "fahrenheit": 100
  }
}

Complete curl command can be found below:

curl -X POST \
    -H 'Content-Type:application/json' \
    -H 'Accept:application/json' \
    -d '{"fahrenheit": 100}' \
    http://localhost:8080/fahrenheit_to_celsius | jq .

You should have a reply similar to this one:

{
  "id": "2287167f-1392-480e-8e20-6acd5922dfac",
  "workflowdata": {
    "fahrenheit": 100,
    "subtractValue": "32.0",
    "multiplyValue": "0.5556",
    "difference": 68.0,
    "product": 37.7808
    }
  }
}

Deploying with Kogito Operator

In the operator directory you'll find the custom resources needed to deploy this example on OpenShift with the Kogito Operator.