quickstarts/tutorials/workflow/java/resiliency-and-compensation

Resiliency & Compensation

This tutorial demonstrates how to improve resiliency when activities are executed and how to include compensation actions when activities return an error. For more on workflow resiliency read the Dapr docs.

Inspect the code

Open the ResiliencyAndCompensationWorkflow.java file in the tutorials/workflow/java/resiliency-and-compensation/src/main/java/io/dapr/springboot/examples/resiliency/ folder. This file contains the definition for the workflow. This workflow implements an activity retry policy on all the associated activities and compensating logic if an activity throws an exception.

graph LR
   SW((Start
   Workflow))
   A1[MinusOne]
   A2[Division]
   EX{Division
   Exception?}
   A3[PlusOne]
   EW((End
   Workflow))
   SW --> A1
   A1 --> A2
   A2 --> EX
   EX -- yes --> A3
   EX -- no --> EW
   A3 --> EW

Run the tutorial

1. Use a terminal to navigate to the tutorials/workflow/java/resiliency-and-compensation folder.

2. Build and run the project using Maven.

   mvn spring-boot:test-run
   

3. Use the POST request in the resiliency-compensation.http file to start the workflow with a workflow input value of 1, or use this cURL command:

   curl -i --request POST \
   --url http://localhost:8080/start/1
   

   When the workflow input is 1, the MinusOne activity will subtract 1 resulting in a 0. This value is passed to the Division activity, which will throw an error because the divisor is 0. The Division activity will be retried three times but all will fail the same way as the divisor has not changed. Finally the compensation action PlusOne will be executed, increasing the value back to 1 before returning the result.

   The app logs should output the following:

   i.d.s.e.resiliency.MinusOneActivity      : io.dapr.springboot.examples.resiliency.MinusOneActivity: Received input:  1
   i.d.s.e.resiliency.DivisionActivity      : io.dapr.springboot.examples.resiliency.DivisionActivity : Received divisor: 0
   i.d.s.e.resiliency.DivisionActivity      : io.dapr.springboot.examples.resiliency.DivisionActivity : Received divisor: 0
   i.d.s.e.resiliency.DivisionActivity      : io.dapr.springboot.examples.resiliency.DivisionActivity : Received divisor: 0
   i.d.s.e.resiliency.PlusOneActivity       : io.dapr.springboot.examples.resiliency.PlusOneActivity: Received input:  0
   

4. Use the GET request in the resiliency-compensation.http file to get the status of the workflow, or use this cURL command:

   curl --request GET --url http://localhost:8080/output
   

   Since 1 is used as the input, the expected output of the workflow is:

   "1"
   

5. Stop the application by pressing Ctrl+C.