# gizweb:presence

Who is in a room now: each person renews a lease with a heartbeat, and a person whose lease ended is gone.

```gizlang
import * as Presence from "gizweb:presence";
```

## Types

### `Presence`

```gizlang
type Presence = { @Key room: string; @Key person: string; expires: i64; }
```

PERSON's lease in ROOM, which ends at `expires` (ms).

- `room`: `string`
- `person`: `string`
- `expires`: `i64`

## Functions

### `install`

```gizlang
function install(d: Data.Db): bool throws Model.Rejection
```

Makes the presence table when it is not there.

Effects: fail, read, write, console, io.

### `beat`

```gizlang
function beat(d: Data.Db, room: string, person: string, expires: i64): bool throws Model.Rejection
```

Renews PERSON's lease in ROOM until EXPIRES.

Effects: fail, read, write, console, io.

### `present`

```gizlang
function present(d: Data.Db, room: string, now: i64): Vec<string> throws Model.Rejection
```

The people in ROOM at NOW, ordered by id.

Effects: fail, read, write, console, io.