Scheduler

A scheduling service which supports and orchestrates running tasks/jobs immediately, in the future or on a recurring basis.

Project Structure

• services - AWS Lambda functions written in Node.js (TypeScript)
• stacks - Serverless stack definition written in TypeScript
• web - React application with TypeScript

Architecture

Serverless stack on AWS

Technologies

Backend

• SST - a framework that makes it easy to build and deploy full-stack serverless applications.
• Amazon API Gateway - a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale.
• AWS Lambda - a serverless, event-driven compute service that lets you run code for virtually any type of application or backend service without provisioning or managing servers.
• Amazon DynamoDB - a fully managed, serverless, key-value NoSQL database designed to run high-performance applications at any scale.
• Amazon EventBridge - a serverless event bus that lets you receive, filter, transform, route, and deliver events.
• Amazon SQS - a service that lets you send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be available.

Frontend

• React - a JavaScript library for building user interfaces.
• Mantine - a fully featured React components library.
• Redux Toolkit - the official, opinionated, batteries-included toolset for efficient Redux development.
• Tabler Icons - an icon library with over 2900 pixel-perfect icons for web design.
• dayjs - 2KB immutable date time library alternative to Moment.js with the same modern API.

Workflow

Running jobs on their scheduled time:

• Immediate
• Future time
• Recurring (weekly/daily)

Immediate

1. API is invoked to create an immediate job
2. API Gateway passes the request to Lambda
3. Lambda executes the job (sending a message to SQS)

Future time

1. API is invoked to create a future job
2. API Gateway passes the request to Lambda
3. Lambda stores the job to DynamoDB

Recurring

1. EventBridge invokes Lambda in every minute
2. Lambda checks DynamoDB for scheduled jobs
3. Lambda executes any scheduled jobs (sending messages to SQS)

CRUD APIs

List Schedules

GET /schedules

e.g. response:

[
  {
    "payload": "Nice one",
    "jobId": "1d24b4d0-5ac7-11ed-8cbc-1fbf296d5db5",
    "recurring": "daily",
    "minute": 27791516
  }
]

Get Schedule

GET /schedules/{jobId}

e.g. response:

{
  "payload": "Nice one",
  "jobId": "1d24b4d0-5ac7-11ed-8cbc-1fbf296d5db5",
  "recurring": "daily",
  "minute": 27791516
}

Create Schedule

POST /schedules

e.g. request body:

{
  "payload": "cool stuff",
  "minute": 27789898,
  "recurring": "none"
}

e.g. response:

{
  "jobId": "0e8bcf60-5b23-11ed-83c8-bf0a6fed592f",
  "payload": "cool stuff",
  "minute": 27789898,
  "recurring": "none"
}

Update Schedule

PUT /schedules/{jobId}

e.g. request body:

{
  "payload": "drink more water",
  "minute": 27789493,
  "recurring": "none"
}

e.g. response:

{
  "payload": "drink more water",
  "jobId": "6dc533e0-5a74-11ed-b427-6dc61c712f9d",
  "recurring": "none",
  "minute": 27789493
}

Delete Schedule

DELETE /schedules/{jobId}

e.g. response:

Status 200

User Interface

Deployment

The React application is deployed on AWS Amplify.