workflows-ts/demo/visualization/src/workflow.ts

import { Workflow, workflowEvent } from "@llamaindex/workflow-core";

//#region define workflow events
const startEvent = workflowEvent<string>({
  debugLabel: "start",
});
const branchAEvent = workflowEvent<string>({
  debugLabel: "branchA",
});
const branchBEvent = workflowEvent<string>({
  debugLabel: "branchB",
});
const branchCEvent = workflowEvent<string>({
  debugLabel: "branchC",
});
const branchCompleteEvent = workflowEvent<string>({
  debugLabel: "branchComplete",
});
const allCompleteEvent = workflowEvent<string>({
  debugLabel: "allComplete",
});
const stopEvent = workflowEvent<string>({
  debugLabel: "stop",
});
//#endregion

export function setupWorkflowEvents(workflow: Workflow) {
  workflow.handle([startEvent], async (ctx) => {
    const { sendEvent, stream } = ctx;
    // emit 3 different events, handled separately

    sendEvent(branchAEvent.with("Branch A"));
    sendEvent(branchBEvent.with("Branch B"));
    sendEvent(branchCEvent.with("Branch C"));

    const results = await stream.filter(branchCompleteEvent).take(3).toArray();

    return allCompleteEvent.with(results.map((e) => e.data).join(", "));
  });

  workflow.handle([branchAEvent], (_context1, branchA) => {
    return branchCompleteEvent.with(branchA.data);
  });

  workflow.handle([branchBEvent], (_context2, branchB) => {
    return branchCompleteEvent.with(branchB.data);
  });

  workflow.handle([branchCEvent], (_context3, branchC) => {
    return branchCompleteEvent.with(branchC.data);
  });

  workflow.handle([allCompleteEvent], (_context4, allComplete) => {
    return stopEvent.with(allComplete.data);
  });

  return workflow;
}