Kogito Serverless Workflow - Error Example

Description

This example contains a simple workflow service that illustrate error handling. The service is described using JSON format as defined in the CNCF Serverless Workflow specification.

The workflow check if the number is odd or even and print a message indicating that. The main feature of this demo is that if the number is odd, an exception is thrown, and it is the exception error handling the one that sets the odd message.

Hence, this workflow expects JSON input containing a natural number. This number is passed using a service operation to EvenService java class. If the number is even, the workflow moves to the next defined state, injecting “even” numberType. But if the number is odd, the class throws an IllegalArgumentException. This exception is handled and redirected to odd inject node by using inline workflow error handling. This basically consists on adding onErrors field, where the expected exception is specified in code and the target state (a node injecting “odd” numberType) in transition. Finally, both execution paths finish on the same node, which prints the calculated eventType.

Installing and Running

Prerequisites

You will need:

• Java 11+ installed
• Environment variable JAVA_HOME set accordingly
• Maven 3.6.2+ installed

When using native image compilation, you will also need:

• GraalVm 19.3.1+ 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/serverless-workflow-error-quarkus-{version}-runner

Submit a request

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

{
  "workflowdata": {
   "number" : 2
  }
}

Complete curl command can be found below:

curl -X POST -H 'Content-Type:application/json' -H 'Accept:application/json' -d '{"workflowdata" : {"number": 2}}' http://localhost:8080/error

In Quarkus you should see the log message printed:

even

If you would like to check odd number

{
  "workflowdata": {
   "number" : 1
  }
}

Complete curl command can be found below:

curl -X POST -H 'Content-Type:application/json' -H 'Accept:application/json' -d '{"workflowdata" : {"number": 1}}' http://localhost:8080/error

In Quarkus you should see the log message printed:

odd