---
type: docs
title: "Scheduler overview"
linkTitle: "Overview"
weight: 1000
description: "Overview of the scheduler API building block"
---

The Scheduler API works as an orchestrator for scheduling jobs in the future,  either at a specific time or a specific interval. The scheduler helps you with jobs like:

- Scalable actor reminders
- Scheduling any Dapr API to run at specific times or intervals, like when:
  - Sending pub/sub messages
  - Calling service invocations and input bindings
  - Saving state to a state store 

The Scheduler consists of two parts that work together to seamlessly schedule jobs across all of Dapr's API building blocks:
- The Scheduler building block
- [The Scheduler control plane service]({{< ref "concepts/dapr-services/scheduler.md" >}})

This article covers the Scheduler API building block.

## How it works

The Scheduler building block is a job orchestrator, not executor. The design guarantees *at least once* job execution with a bias towards durability and horizontal scaling over precision. This means:
- **Guaranteed:** A job is never invoked *before* the schedule is due.
- **Not guaranteed:** A ceiling time on when the job is invoked *after* the due time is reached.

## Features

### Delayed pub/sub

The Scheduler building block enables you to delay your pub/sub messaging. You can publish a message in a future specific time -- for example, a week from today, or a specific UTC date/time.

### Scheduled service invocation

The Scheduler building block provides the [service invocation]({{< ref service-invocation-overview.md >}}) building block with an orchestrator that schedules method calls between applications.

### Schedule jobs across multiple replicas

The Scheduler service enables the scheduling of jobs to scale across multiple replicas, while guaranteeing that a job is only triggered by 1 scheduler service instance.

### Scheduler reminders

The [Dapr Workflow building block]({{< ref workflow-overview.md >}}) is built on top of Actor Reminders. The Scheduler building block improves the performance and scale of actor reminders, which present scale limitation issues. 

### Store job details separately from user-associated data

If a user would like to store their user associated data in a specific state store of their choosing, then they can provision a state store using the Dapr State Management Building Block and set `jobStateStore ` as `true` in the state store component’s metadata section. Having the `jobStateStore` set to `true` means that their user associate data will be stored in the state store of their choosing, but their job details will still be stored in the embedded etcd. If the `jobStateStore` is not configured, then the embedded etcd will be used to store both the job details and the user associated data.

## Try out the Scheduler

You can try out the Scheduler building block directly in your application. After [Dapr is installed]({{< ref install-dapr-cli.md >}}), you can begin using the Scheduler API, starting with [the How-to: Set up a Scheduler guide]({{< ref howto-use-scheduler.md >}}).

## Next steps

- [Learn how to use the scheduler in your environment]({{< ref howto-use-scheduler.md >}})
- [Learn more about the Scheduler control plane service]({{< ref "concepts/dapr-services/scheduler.md" >}})
- [Scheduler API reference]({{< ref scheduler_api.md >}})