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If you use a third-party API that processes data (like video encoding or AI generation) but doesn’t offer webhooks, you usually have to run a cron job to poll for status. With Posthook, you can create a “self-healing” loop that checks the status and reschedules itself if the job isn’t done yet.

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Workflow

  1. Schedule: Trigger the job and schedule the first check.
  2. Handle: Check status. If pending, reschedule. If completed, process the result.
import Posthook from '@posthook/node';
import { Signatures, SignatureVerificationError } from '@posthook/node';

const posthook = new Posthook(process.env.POSTHOOK_API_KEY);
const signatures = new Signatures(process.env.POSTHOOK_SIGNING_KEY);

/* 1. Schedule */
async function startVideoEncoding(videoFile) {
  // 1. Start the job on the 3rd party API
  const job = await transcoderApi.start(videoFile);

  // 2. Schedule the first check for 1 minute later
  await posthook.hooks.schedule({
    path: '/webhooks/check-status',
    postIn: '1m',
    data: {
      jobId: job.id
    }
  });
}

/* 2. Handle */
app.post('/webhooks/check-status', async (req, res) => {
  try {
    const delivery = signatures.parseDelivery(req.body, req.headers);

    const { jobId } = delivery.data;
    const job = await transcoderApi.get(jobId);

    if (job.status === 'completed') {
      // DONE: Process the result
      await db.saveVideo(job.url);
      return res.status(200).send('Video processed');
    }

    if (job.status === 'failed') {
      // FAIL: Handle error (maybe alert team)
      return res.status(200).send('Job failed');
    }

    // PENDING: Reschedule check for another minute
    await posthook.hooks.schedule({
      path: '/webhooks/check-status',
      postIn: '1m',
      data: { jobId }
    });

    res.status(200).send('Still pending, rescheduled');
  } catch (err) {
    if (err instanceof SignatureVerificationError) {
      return res.status(401).json({ error: err.message });
    }
    throw err;
  }
});