Knack Realtime

Knack Realtime

Purpose

Simulates live updates between Knack backend and Vercel dashboards. Enables near-real-time synchronization of HTI operational data without constant polling.

Core Concepts

Knack doesn't offer native WebSocket support, so we implement:

1. Polling: Periodic checks for data changes
2. Webhooks: Knack triggers external endpoints on record events
3. Incremental Updates: Fetch only changed records

Core Functions

poll_updates

Purpose: Check for data changes at regular intervals

Parameters:

• object_key (string, required): Knack object to monitor
• interval_seconds (integer, optional): Polling frequency (default: 60)
• last_check_timestamp (datetime, optional): Only fetch records modified since this time
• on_change (function, optional): Callback when changes detected

Example:

// Poll for new laptops every 60 seconds
poll_updates({
  object_key: "object_1",
  interval_seconds: 60,
  last_check_timestamp: new Date(),
  on_change: (new_records) => {
    console.log(`${new_records.length} new laptops acquired`);
    updateDashboard(new_records);
  }
});

Implementation:

async function poll_updates({ object_key, interval_seconds, on_change }) {
  let last_check = new Date();

  setInterval(async () => {
    const changes = await get_records(object_key, {
      filters: build_filter({
        rules: [{
          field: "field_modified_date",
          operator: "is after",
          value: last_check.toISOString()
        }]
      })
    });

    if (changes.records.length > 0) {
      on_change(changes.records);
    }

    last_check = new Date();
  }, interval_seconds * 1000);
}

register_webhook

Purpose: Configure Knack to push updates to Vercel endpoint

Parameters:

• trigger (string, required): "record_created" | "record_updated" | "record_deleted"
• object_key (string, required): Which object to monitor
• url (string, required): Vercel API route to receive webhook
• secret (string, optional): Shared secret for webhook validation

Knack Setup (Manual in Knack Builder):

1. Navigate to Settings → API & Code → Webhooks
2. Create new webhook:
   • Trigger: After Record Create/​Update/​Delete
   • Object: Select target object (e.g., Laptop Inventory)
   • URL: https://your-vercel-app.vercel.app/​api/​knack-webhook
   • Method: POST

Vercel API Route (/​api/​knack-webhook.js):

export default async function handler(req, res) {
  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' });
  }

  const { object_key, record, action } = req.body;

  // Validate webhook (optional)
  const signature = req.headers['x-knack-signature'];
  if (!validateSignature(signature, req.body)) {
    return res.status(401).json({ error: 'Invalid signature' });
  }

  // Process update
  if (action === 'created') {
    console.log(`New record in ${object_key}:`, record);
    await updateCache(object_key, record);
  }

  return res.status(200).json({ received: true });
}

detect_changes

Purpose: Identify which records have changed since last sync

Example:

const changed = await detect_changes({
  object_key: "object_1",
  since: last_sync_timestamp,
  fields_to_watch: ["field_status", "field_county"]
});

Logic:

• Query records modified after timestamp
• Compare field values to cached state
• Return only records with actual changes

HTI-Specific Use Cases

Dashboard Live Updates

Device Status Changes

// Real-time status updates for ops dashboard
poll_updates({
  object_key: "object_1",
  interval_seconds: 30, // Check every 30 seconds
  on_change: (devices) => {
    const ready = devices.filter(d => d.status === "Ready for Donation");
    if (ready.length > 0) {
      notifyTeam(`${ready.length} new devices ready for distribution`);
    }
  }
});

Training Session Registrations

// Monitor new sign-ups for digital literacy classes
poll_updates({
  object_key: "object_training",
  interval_seconds: 120, // Every 2 minutes
  on_change: (sessions) => {
    updateCapacityWidget(sessions);
  }
});

Webhook-Driven Updates

New Donation Notification

// Webhook fires when new donation record created
register_webhook({
  trigger: "record_created",
  object_key: "object_donations",
  url: "https://hubdash.vercel.app/​api/​donation-alert",
  on_receive: async (donation) => {
    await sendSlackNotification({
      channel: "#donations",
      text: `New donation: ${donation.org_name} - ${donation.laptop_count} laptops`
    });
  }
});

Status Change Workflow

// When device status changes to "Ready", trigger distribution workflow
register_webhook({
  trigger: "record_updated",
  object_key: "object_1",
  url: "https://hubdash.vercel.app/​api/​device-ready",
  filter_condition: (record) => record.status === "Ready for Donation"
});

Performance Optimization

Smart Polling

// Adaptive polling: slower when idle, faster when active
let poll_interval = 60; // Start at 60 seconds

poll_updates({
  object_key: "object_1",
  interval_seconds: poll_interval,
  on_change: (records) => {
    if (records.length > 10) {
      poll_interval = 15; // Speed up if lots of activity
    } else {
      poll_interval = Math.min(poll_interval + 15, 180); // Slow down if quiet
    }
  }
});

Delta Sync

// Only fetch modified fields, not entire records
const changes = await poll_updates({
  object_key: "object_1",
  fields: ["field_status", "field_county"], // Only these fields
  since: last_check
});

Rate Limit Considerations

Knack Limit: 10 requests/​second

Polling Strategy:

• Short interval (30s) = 2 requests/​minute
• Medium interval (60s) = 1 request/​minute
• Long interval (120s) = 0.5 requests/​minute

Best Practice: Use webhooks for critical updates, polling for less urgent data

Error Handling

async function robust_poll(object_key) {
  try {
    const updates = await poll_updates({ object_key });
    return updates;
  } catch (error) {
    if (error.status === 429) {
      // Rate limit - increase interval
      console.warn("Rate limit hit, slowing polling...");
      await sleep(5000);
    } else if (error.status >= 500) {
      // Server error - retry with backoff
      await exponentialBackoff(poll_updates, { object_key });
    } else {
      throw error;
    }
  }
}

Vercel Integration

API Route Structure

/​api
  /​knack-webhook.js       # Receives Knack webhooks
  /​poll-updates.js        # Serverless function for polling
  /​cache-invalidate.js    # Clear cache on updates

Environment Variables

KNACK_WEBHOOK_SECRET=your_secret_here
KNACK_APP_ID=your_app_id
KNACK_API_KEY=your_api_key

Testing

Webhook Testing

# Simulate Knack webhook locally
curl -X POST http://localhost:3000/​api/​knack-webhook \
  -H "Content-Type: application/​json" \
  -d '{
    "object_key": "object_1",
    "action": "created",
    "record": { "id": "test123", "status": "Ready" }
  }'

Polling Simulation

// Test polling logic without hitting Knack API
const mock_changes = [
  { id: "1", status: "Ready" },
  { id: "2", status: "Converted" }
];

on_change(mock_changes);

Integration Points

• knack_reader: Fetch changed records
• knack_filter_sort: Filter for modified_since queries
• knack_cache_optimizer: Invalidate cache on updates
• knack_dashboard_ai: Trigger metric recalculation on changes
• knack_reporting_sync: Real-time progress toward goals

Grant Compliance

• Log all webhook triggers for audit trail
• Track real-time progress toward 3,500 laptop goal
• Alert when approaching quarterly reporting deadlines
• Monitor training session capacity in real-time