Initialize with JavaScript or TypeScript

🚀 Installation

Install the following packages by NPM command:

npm i sequential-workflow-model sequential-workflow-machine

🎬 Usage

You can use the engine in a JavaScript or TypeScript application. We recommend to use TypeScript because a workflow uses a lot of data structures and it's hard to maintain data integrity.

At the beginning you need to define the type of your workflow definition.

import { Definition } from 'sequential-workflow-model';

interface MyDefinition extends Definition {
  properties: {
    verbose: boolean;
  };
}

Next, define your step types.

import { Step } from 'sequential-workflow-model';

interface DownloadHtmlStep extends Step {
  componentType: 'task';
  type: 'downloadHtml';
  properties: {
    pageUrl: string;
  };
}

// ...

Prepare the workflow definition.

const definition: MyDefinition = {
  properties: {
    verbose: true,
  },
  sequence: [
    {
      id: '0x00001',
      componentType: 'task',
      type: 'downloadHtml',
      name: 'Download google.com',
      properties: {
        pageUrl: 'https://www.google.com',
      },
    },
  ],
};

Prepare the global state interface.

interface WorkflowGlobalState {
  html: string | null;
}

Prepare activities for your steps. The engine supports multiple types of activities. The basic activity is the atom activity. It's a simple handler that executes an atomic step and updates the global state.

import { createAtomActivity } from 'sequential-workflow-machine';

interface DownloadHtmlStepState {
  attempt: number;
}

const downloadHtmlActivity = createAtomActivity<DownloadHtmlStep, WorkflowGlobalState, DownloadHtmlStepState>('downloadHtml', {
  init: () => ({
    attempt: 0,
  }),
  handler: async (step: DownloadHtmlStep, globalState: WorkflowGlobalState, activityState: DownloadHtmlStepState) => {
    globalState.html = await downloadHtml(step.properties.pageUrl);
    activityState.attempt++;
  },
});

Now we can create the activity set. The activity set is a collection of all supported activities.

import { createActivitySet } from 'sequential-workflow-machine';

const activitySet =  createActivitySet<WorkflowGlobalState>([
  downloadHtmlActivity,
]);

Finally, we can create the workflow machine and run it.

import { createWorkflowMachineBuilder } from 'sequential-workflow-machine';

const builder = createWorkflowMachineBuilder<WorkflowGlobalState>(activitySet);
const machine = builder.build(definition);
const interpreter = machine.create({
  init: () => {
    return {
      html: null,
    };
  }
});
interpreter.onChange(() => { /* ... */ });
interpreter.onDone(() => { /* ... */ });
interpreter.start();

That's it!