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How to: Author and manage workflows

Let’s create a Dapr workflow and invoke it using the console. With the provided workflow example, you will:

This example uses the default configuration from dapr init in self-hosted mode.

Prerequisites

  • Verify you’re using the latest proto bindings

Set up the environment

Clone the JavaScript SDK repo and navigate into it.

git clone https://github.com/dapr/js-sdk
cd js-sdk

From the JavaScript SDK root directory, navigate to the Dapr Workflow example.

cd examples/workflow/authoring

Run the following command to install the requirements for running this workflow sample with the Dapr JavaScript SDK.

npm install

Run the activity-sequence.ts

The activity-sequence file registers a workflow and an activity with the Dapr Workflow runtime. The workflow is a sequence of activities that are executed in order. We use DaprWorkflowClient to schedule a new workflow instance and wait for it to complete.

const daprHost = "localhost";
const daprPort = "50001";
const workflowClient = new DaprWorkflowClient({
  daprHost,
  daprPort,
});
const workflowRuntime = new WorkflowRuntime({
  daprHost,
  daprPort,
});

const hello = async (_: WorkflowActivityContext, name: string) => {
  return `Hello ${name}!`;
};

const sequence: TWorkflow = async function* (ctx: WorkflowContext): any {
  const cities: string[] = [];

  const result1 = yield ctx.callActivity(hello, "Tokyo");
  cities.push(result1);
  const result2 = yield ctx.callActivity(hello, "Seattle");
  cities.push(result2);
  const result3 = yield ctx.callActivity(hello, "London");
  cities.push(result3);

  return cities;
};

workflowRuntime.registerWorkflow(sequence).registerActivity(hello);

// Wrap the worker startup in a try-catch block to handle any errors during startup
try {
  await workflowRuntime.start();
  console.log("Workflow runtime started successfully");
} catch (error) {
  console.error("Error starting workflow runtime:", error);
}

// Schedule a new orchestration
try {
  const id = await workflowClient.scheduleNewWorkflow(sequence);
  console.log(`Orchestration scheduled with ID: ${id}`);

  // Wait for orchestration completion
  const state = await workflowClient.waitForWorkflowCompletion(id, undefined, 30);

  console.log(`Orchestration completed! Result: ${state?.serializedOutput}`);
} catch (error) {
  console.error("Error scheduling or waiting for orchestration:", error);
}

In the code above:

  • workflowRuntime.registerWorkflow(sequence) registers sequence as a workflow in the Dapr Workflow runtime.
  • await workflowRuntime.start(); builds and starts the engine within the Dapr Workflow runtime.
  • await workflowClient.scheduleNewWorkflow(sequence) schedules a new workflow instance with the Dapr Workflow runtime.
  • await workflowClient.waitForWorkflowCompletion(id, undefined, 30) waits for the workflow instance to complete.

In the terminal, execute the following command to kick off the activity-sequence.ts:

npm run start:dapr:activity-sequence

Expected output

You're up and running! Both Dapr and your app logs will appear here.

...

== APP == Orchestration scheduled with ID: dc040bea-6436-4051-9166-c9294f9d2201
== APP == Waiting 30 seconds for instance dc040bea-6436-4051-9166-c9294f9d2201 to complete...
== APP == Received "Orchestrator Request" work item with instance id 'dc040bea-6436-4051-9166-c9294f9d2201'
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Rebuilding local state with 0 history event...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Processing 2 new history event(s): [ORCHESTRATORSTARTED=1, EXECUTIONSTARTED=1]
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Waiting for 1 task(s) and 0 event(s) to complete...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Returning 1 action(s)
== APP == Received "Activity Request" work item
== APP == Activity hello completed with output "Hello Tokyo!" (14 chars)
== APP == Received "Orchestrator Request" work item with instance id 'dc040bea-6436-4051-9166-c9294f9d2201'
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Rebuilding local state with 3 history event...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Processing 2 new history event(s): [ORCHESTRATORSTARTED=1, TASKCOMPLETED=1]
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Waiting for 1 task(s) and 0 event(s) to complete...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Returning 1 action(s)
== APP == Received "Activity Request" work item
== APP == Activity hello completed with output "Hello Seattle!" (16 chars)
== APP == Received "Orchestrator Request" work item with instance id 'dc040bea-6436-4051-9166-c9294f9d2201'
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Rebuilding local state with 6 history event...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Processing 2 new history event(s): [ORCHESTRATORSTARTED=1, TASKCOMPLETED=1]
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Waiting for 1 task(s) and 0 event(s) to complete...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Returning 1 action(s)
== APP == Received "Activity Request" work item
== APP == Activity hello completed with output "Hello London!" (15 chars)
== APP == Received "Orchestrator Request" work item with instance id 'dc040bea-6436-4051-9166-c9294f9d2201'
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Rebuilding local state with 9 history event...
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Processing 2 new history event(s): [ORCHESTRATORSTARTED=1, TASKCOMPLETED=1]
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Orchestration completed with status COMPLETED
== APP == dc040bea-6436-4051-9166-c9294f9d2201: Returning 1 action(s)
INFO[0006] dc040bea-6436-4051-9166-c9294f9d2201: 'sequence' completed with a COMPLETED status.  app_id=activity-sequence-workflow instance=kaibocai-devbox scope=wfengine.backend type=log ver=1.12.3
== APP == Instance dc040bea-6436-4051-9166-c9294f9d2201 completed
== APP == Orchestration completed! Result: ["Hello Tokyo!","Hello Seattle!","Hello London!"]

Next steps