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java-sdk/spring-boot-examples/workflows/README.md

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Dapr Spring Boot Workflow Examples

This application allows you to run different workflow patterns including:

  • Chained Activities
  • Parent/Child Workflows
  • Continue workflow by sending External Events
  • Fan Out/In activities for parallel execution

Running these examples from source code

To run these examples you will need:

  • Java SDK
  • Maven
  • Docker or a container runtime such as Podman

From the spring-boot-examples/workflows directory you can start the service by running the following command:

../../mvnw spring-boot:test-run

By running the spring-boot:test-run goal, the application is loaded using the test configurations configured using Testcontainers to boostrap the Dapr sidecar and control plane.

Once the application is running you can trigger the different patterns by sending the following requests:

Chaining Activities Workflow example

The io.dapr.springboot.examples.wfp.chain.ChainWorkflow executes three chained activities. For this example the ToUpperCaseActivity.java is used to transform to upper case three strings from an array.

graph LR
   SW((Start
   Workflow))
   A1[Activity1]
   A2[Activity2]
   A3[Activity3]
   EW((End
   Workflow))
   SW --> A1
   A1 --> A2
   A2 --> A3
   A3 --> EW

To start the workflow with the three chained activities you can run:

curl -X POST localhost:8080/wfp/chain -H 'Content-Type: application/json'

As result from executing the request you should see:

TOKYO, LONDON, SEATTLE

In the application output you should see the workflow activities being executed.

io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.chain.ChainWorkflow
i.d.s.e.w.WorkflowPatternsRestController : Workflow instance 7625b4af-8c04-408a-93dc-bad753466e43 started
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Starting Activity: io.dapr.springboot.examples.wfp.chain.ToUpperCaseActivity
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Message Received from input: Tokyo
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Sending message to output: TOKYO
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Starting Activity: io.dapr.springboot.examples.wfp.chain.ToUpperCaseActivity
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Message Received from input: London
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Sending message to output: LONDON
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Starting Activity: io.dapr.springboot.examples.wfp.chain.ToUpperCaseActivity
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Message Received from input: Seattle
i.d.s.e.wfp.chain.ToUpperCaseActivity    : Sending message to output: SEATTLE
io.dapr.workflows.WorkflowContext        : Workflow finished with result: TOKYO, LONDON, SEATTLE

Parent / Child Workflows example

In this example we start a Parent workflow that calls a child workflow that execute one activity that reverses an input string.

The Parent workflow looks like this:

graph LR
   SW((Start
   Workflow))
   subgraph for each word in the input
    GWL[Call child workflow]
   end
   EW((End
   Workflow))
   SW --> GWL
   GWL --> EW

The Child workflow looks like this:

graph LR
   SW((Start
   Workflow))
   A1[Activity1]
   EW((End
   Workflow))
   SW --> A1
   A1 --> EW

To start the parent workflow you can run:

To start the workflow with the three chained activities you can run:

curl -X POST localhost:8080/wfp/child -H 'Content-Type: application/json'

As result from executing the request you should see:

!wolfkroW rpaD olleH

In the application output you should see the workflow activities being executed.

io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.child.ParentWorkflow
io.dapr.workflows.WorkflowContext        : calling childworkflow with input: Hello Dapr Workflow!
i.d.s.e.w.WorkflowPatternsRestController : Workflow instance f3ec9566-a0fc-4d28-8912-3f3ded3cd8a9 started
io.dapr.workflows.WorkflowContext        : Starting ChildWorkflow: io.dapr.springboot.examples.wfp.child.ChildWorkflow
io.dapr.workflows.WorkflowContext        : ChildWorkflow received input: Hello Dapr Workflow!
io.dapr.workflows.WorkflowContext        : ChildWorkflow is calling Activity: io.dapr.springboot.examples.wfp.child.ReverseActivity
i.d.s.e.wfp.child.ReverseActivity        : Starting Activity: io.dapr.springboot.examples.wfp.child.ReverseActivity
i.d.s.e.wfp.child.ReverseActivity        : Message Received from input: Hello Dapr Workflow!
i.d.s.e.wfp.child.ReverseActivity        : Sending message to output: !wolfkroW rpaD olleH
io.dapr.workflows.WorkflowContext        : ChildWorkflow finished with: !wolfkroW rpaD olleH
io.dapr.workflows.WorkflowContext        : childworkflow finished with: !wolfkroW rpaD olleH

ContinueAsNew Workflows example

In this example we start a workflow that every 3 seconds schedule a new workflow consistently. This workflow executes one activity called CleanUpActivity that takes 2 seconds to complete. This loops repeat consistently for 5 times.

To start the workflow you can run:

curl -X POST localhost:8080/wfp/continueasnew -H 'Content-Type: application/json'

As result from executing the request you should see:

{"cleanUpTimes":5}

In the application output you should see the workflow activities being executed.

io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.continueasnew.ContinueAsNewWorkflow
io.dapr.workflows.WorkflowContext        : call CleanUpActivity to do the clean up
i.d.s.e.w.WorkflowPatternsRestController : Workflow instance b808e7d6-ab47-4eba-8188-dc9ff8780764 started
i.d.s.e.w.continueasnew.CleanUpActivity  : Starting Activity: io.dapr.springboot.examples.wfp.continueasnew.CleanUpActivity
i.d.s.e.w.continueasnew.CleanUpActivity  : start clean up work, it may take few seconds to finish... Time:10:48:45
io.dapr.workflows.WorkflowContext        : CleanUpActivity finished
io.dapr.workflows.WorkflowContext        : wait 5 seconds for next clean up
io.dapr.workflows.WorkflowContext        : Let's do more cleaning.
io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.continueasnew.ContinueAsNewWorkflow
io.dapr.workflows.WorkflowContext        : call CleanUpActivity to do the clean up
i.d.s.e.w.continueasnew.CleanUpActivity  : Starting Activity: io.dapr.springboot.examples.wfp.continueasnew.CleanUpActivity
i.d.s.e.w.continueasnew.CleanUpActivity  : start clean up work, it may take few seconds to finish... Time:10:48:50
io.dapr.workflows.WorkflowContext        : CleanUpActivity finished
io.dapr.workflows.WorkflowContext        : wait 5 seconds for next clean up
io.dapr.workflows.WorkflowContext        : Let's do more cleaning.
io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.continueasnew.ContinueAsNewWorkflow
io.dapr.workflows.WorkflowContext        : call CleanUpActivity to do the clean up
i.d.s.e.w.continueasnew.CleanUpActivity  : Starting Activity: io.dapr.springboot.examples.wfp.continueasnew.CleanUpActivity
i.d.s.e.w.continueasnew.CleanUpActivity  : start clean up work, it may take few seconds to finish... Time:10:48:55
io.dapr.workflows.WorkflowContext        : CleanUpActivity finished
io.dapr.workflows.WorkflowContext        : wait 5 seconds for next clean up
io.dapr.workflows.WorkflowContext        : Let's do more cleaning.
io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.continueasnew.ContinueAsNewWorkflow
io.dapr.workflows.WorkflowContext        : call CleanUpActivity to do the clean up
i.d.s.e.w.continueasnew.CleanUpActivity  : Starting Activity: io.dapr.springboot.examples.wfp.continueasnew.CleanUpActivity
i.d.s.e.w.continueasnew.CleanUpActivity  : start clean up work, it may take few seconds to finish... Time:10:49:0
io.dapr.workflows.WorkflowContext        : CleanUpActivity finished
io.dapr.workflows.WorkflowContext        : wait 5 seconds for next clean up
io.dapr.workflows.WorkflowContext        : Let's do more cleaning.
io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.continueasnew.ContinueAsNewWorkflow
io.dapr.workflows.WorkflowContext        : call CleanUpActivity to do the clean up
i.d.s.e.w.continueasnew.CleanUpActivity  : Starting Activity: io.dapr.springboot.examples.wfp.continueasnew.CleanUpActivity
i.d.s.e.w.continueasnew.CleanUpActivity  : start clean up work, it may take few seconds to finish... Time:10:49:5
io.dapr.workflows.WorkflowContext        : CleanUpActivity finished
io.dapr.workflows.WorkflowContext        : wait 5 seconds for next clean up
io.dapr.workflows.WorkflowContext        : We did enough cleaning

External Event Workflow example

In this example we start a workflow that as part of its execution waits for an external event to continue. To correlate workflows and events we use the parameter orderId

To start the workflow you can run:

curl -X POST "localhost:8080/wfp/externalevent?orderId=123" -H 'Content-Type: application/json'

In the application output you should see the workflow activities being executed.

io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.externalevent.ExternalEventWorkflow
io.dapr.workflows.WorkflowContext        : Waiting for approval...
i.d.s.e.w.WorkflowPatternsRestController : Workflow instance 8a55cf6d-9059-49b1-8c83-fbe17567a02e started

You should see the Workflow ID that was created, in this example you don't need to remember this id, as you can use the orderId to find the right instance. When you are ready to approve the order you can send the following request:

To send the event you can run:

curl -X POST "localhost:8080/wfp/externalevent-continue?orderId=123&decision=true" -H 'Content-Type: application/json'

{"approved":true}

In the application output you should see the workflow activities being executed.

i.d.s.e.w.WorkflowPatternsRestController : Workflow instance e86bc464-6166-434d-8c91-d99040d6f54e continue
io.dapr.workflows.WorkflowContext        : approval granted - do the approved action
i.d.s.e.w.externalevent.ApproveActivity  : Starting Activity: io.dapr.springboot.examples.wfp.externalevent.ApproveActivity
i.d.s.e.w.externalevent.ApproveActivity  : Running approval activity...
io.dapr.workflows.WorkflowContext        : approval-activity finished

Fan Out/In Workflow example

In this example we start a workflow that takes an ArrayList of strings and calls one activity per item in the ArrayList. The activities are executed and the workflow waits for all of them to complete to aggregate the results.

graph LR
   SW((Start
   Workflow))
   subgraph for each word in the input
    GWL[GetWordLength]
   end
   ALL[Wait until all tasks
   are completed]
   EW((End
   Workflow))
   SW --> GWL
   GWL --> ALL
   ALL --> EW

To start the workflow you can run:

curl -X POST localhost:8080/wfp/fanoutin -H 'Content-Type: application/json' -d @body.json

As result from executing the request you should see:

{"wordCount":60}

In the application output you should see the workflow activities being executed.

io.dapr.workflows.WorkflowContext        : Starting Workflow: io.dapr.springboot.examples.wfp.fanoutin.FanOutInWorkflow
i.d.s.e.w.WorkflowPatternsRestController : Workflow instance a771a7ba-f9fb-4399-aaee-a2fb0b102e5d started
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Starting Activity: io.dapr.springboot.examples.wfp.fanoutin.CountWordsActivity
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Starting Activity: io.dapr.springboot.examples.wfp.fanoutin.CountWordsActivity
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Starting Activity: io.dapr.springboot.examples.wfp.fanoutin.CountWordsActivity
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity returned: 2.
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity finished
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity returned: 11.
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity returned: 17.
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity finished
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity finished
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Starting Activity: io.dapr.springboot.examples.wfp.fanoutin.CountWordsActivity
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity returned: 21.
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity finished
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Starting Activity: io.dapr.springboot.examples.wfp.fanoutin.CountWordsActivity
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity returned: 9.
i.d.s.e.wfp.fanoutin.CountWordsActivity  : Activity finished
io.dapr.workflows.WorkflowContext        : Workflow finished with result: 60

Testing workflow executions

Workflow execution can be tested using Testcontainers and you can find all the tests for the patterns covered in this application here.