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StartupBuilderby Startups.Studio
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Changelog
PlatformRealtime

Realtime

Realtime pushes Events, Messages and record changes to connected Apps and agents as they happen, resumable from a cursor.

Realtime pushes Events, Messages and record changes to connected Apps and agents as they happen. A client that drops resumes from its cursor and misses nothing.

Contract

  • A stream is a live read by Event selector, such as Order.*, under the caller's Permissions.
  • Every item carries a sequence number. A client reconnects with the last one it saw and receives every later item, in order.
  • Streams run over web sockets or server-sent events at wss://api.sb/<domain>/events/stream, with select and cursor parameters.
  • Presence and typing reach a Channel's members live and are never stored.
  • A stream is a read: it creates no Action per item. Open connections count against a Limit per Tenant.
  • One Channel carries up to 1,000 Messages a second, then shards by Thread.
  • An Agent in a Channel receives its Messages as they arrive. Dashboards refresh live for people.

Verbs

None.

Interfaces

Example

TypeScript
// crumbrun.com delivers from neighborhood bakeries. Each bakery's kitchen screen
// shows new orders the moment they are placed, and survives a dropped connection.
import { $ } from 'startup-builder'

const tickets = document.querySelector('#tickets')!
const cursor = localStorage.getItem('cursor') ?? undefined

for await (const event of $.stream('Order.placed', { cursor })) {
  tickets.append(`${event.data.order.$id}\n`)
  localStorage.setItem('cursor', String(event.seq))
}