Give new displays a program automatically

By the end, every new display gets the program of its location by itself, a few seconds after it appears in the fleet. If a display moves to another location, it takes on that location's program. Nobody has to remember to assign content after a rollout.

How it works#

The receiver keeps a table of which location gets which program, plus a default for displays without a location.

Steps#

1. Write down the table of locations and programs as JSON. Take the location IDs from GET /v1/locations and the program IDs from the portal address:

   JSONCopy

   {  "loc_01KFB7QPW0LOCATION00000001": "sch_01KWVAFRM0ZETPAN0000000001",  "loc_01KFB7QPW0LOCATION00000002": "sch_01KWVAFRM0ZETPAN0000000002",  "default": "sch_01KWVAFRM0ZETPAN0000000003"}

2. Save the receiver:

   TypeScriptCopy

   // auto-assign.ts: node auto-assign.tsimport { createServer } from 'node:http';import { createHmac, timingSafeEqual } from 'node:crypto';import { readFileSync } from 'node:fs'; const SECRET = process.env.WEBHOOK_SECRET ?? ''; // whsec_…const API = process.env.SZENERA_API;const KEY = process.env.SZENERA_API_KEY; // fleet.player.read and schedule.updateconst PROGRAMS: Record<string, string> = JSON.parse(readFileSync('programs.json', 'utf8'));const seen = new Set<string>(); function isFromSignage(rawBody: string, header: string): boolean {  const expected = createHmac('sha256', SECRET).update(rawBody).digest('base64url');  const a = Buffer.from(expected);  const b = Buffer.from(header);  return a.length === b.length && timingSafeEqual(a, b);} async function call(method: string, path: string, body?: unknown) {  const res = await fetch(`${API}${path}`, {    method,    headers: { Authorization: `Bearer ${KEY}`, 'Content-Type': 'application/json' },    body: body === undefined ? undefined : JSON.stringify(body),  });  if (!res.ok) throw new Error(`${method} ${path}: ${res.status} ${await res.text()}`);  return res.json();} async function assignProgramOfLocation(playerId: string): Promise<void> {  const { player } = await call('GET', `/v1/players/${playerId}`);  const scheduleId = PROGRAMS[player.locationId ?? ''] ?? PROGRAMS.default;  if (!scheduleId) return;  await call('PUT', `/v1/players/${playerId}/program`, {    program: { kind: 'schedule', scheduleId },  });  console.log(`${player.name}: ${scheduleId}`);} createServer((req, res) => {  const chunks: Buffer[] = [];  req.on('data', (chunk) => chunks.push(chunk));  req.on('end', async () => {    const raw = Buffer.concat(chunks).toString('utf8');    if (!isFromSignage(raw, String(req.headers['x-signature'] ?? ''))) {      res.writeHead(401).end();      return;    }    res.writeHead(204).end(); // Answer within 10 seconds, work afterwards     const deliveryId = String(req.headers['x-delivery-id']);    if (seen.has(deliveryId)) return;    seen.add(deliveryId);     const event = req.headers['x-event-type'];    const payload = JSON.parse(raw);    const moved = event === 'fleet.player.updated' && payload.changedFields?.includes('locationId');    if (event === 'fleet.player.created' || moved) {      await assignProgramOfLocation(payload.playerId).catch((error) => console.error(error));    }  });}).listen(8080);

3. Create the endpoint in the portal under Settings › For developers › Webhooks with Create endpoint. Enter your https address, choose fleet.player.created and fleet.player.updated under Subscribed events, and click Create. Copy the secret into WEBHOOK_SECRET and start the receiver.

4. Try it with a new web display, see Create a display and give it content, but without assigning a program. A few seconds later, GET /v1/players/{id}/program names the program of its location.

Assigning the same program twice is harmless, so a retried delivery does no damage even after a restart of the receiver.

Check the result#

• The receiver logs one line per new display with its name and program.
• In the portal, the new display shows the program of its location.
• In the Delivery log of the endpoint, every delivery shows Delivered with HTTP 204.

If something goes wrong#

Related#

• Create a display and give it content
• Post to Teams or Slack when a display goes offline
• Event types: content, programs, devices, apps