# IReminderService.RegisterOrUpdateReminder(GrainId, string, TimeSpan, TimeSpan)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.reminders/orleans.ireminderservice/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.reminders/orleans.ireminderservice/methods/)

```csharp
public abstract Task<IGrainReminder> RegisterOrUpdateReminder(GrainId grainId, string reminderName, TimeSpan dueTime, TimeSpan period)
```

Registers a new reminder or updates an existing one.

### Parameters

- `grainId` (`GrainId`): A reference to the grain which the reminder is being registered or updated on behalf of.
- `reminderName` (`string`): The reminder name.
- `dueTime` (`TimeSpan`): The amount of time to delay before firing the reminder initially.
- `period` (`TimeSpan`): The time interval between invocations of the reminder.

### Returns

The reminder.