npm package: @sourceloop/scheduler-service
Description: Scheduler Microservice.
Author: Sourcefuse
Latest version: 18.0.6

# @sourceloop/scheduler-service

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## Overview

This is a loopback4 component for scheduling events in calendar (scheduler/calendar server).

Various features of Scheduler Service:

1. CRUD feature:
   Basic add/edit/delete Event/Invitation in calendar. (As a REST API)

2. Reminder Feature:
   Support or provide integration with notification/reminder service, which has the option of sending email/popup and SMS notification.

3. Importing Calendar:
   The Scheduler supports exporting all its event data to iCal format, and it supports importing events from an iCal file into the Scheduler.

4. Third party calendar support:
   Provide a way to import events information from third party components like : Outlook and Google Calendar.

Main feature set:

- Calendar
- Calendar Subscription
- Working Hours
- Events
- Event Attendee
- Event Attachment

You can see the database schema [here](#database-schema).

To get started with a basic implementation of this service, see [/sandbox/scheduler-example](https://github.com/sourcefuse/loopback4-microservice-catalog/tree/master/sandbox/scheduler-example).

## Install

```sh
npm install @sourceloop/scheduler-service
```

### Workflow Diagrams

![Schedular](https://user-images.githubusercontent.com/82804130/127480876-7dad27cf-11c6-4dbc-9988-f7af6f91c5b8.jpg)

![event](https://user-images.githubusercontent.com/82804130/127480906-3c70d4e0-03b8-426f-bb63-ec726eb39353.jpg)

### Usage

- Create a new Loopback4 Application (If you don't have one already)
  `lb4 testapp`
- Install the scheduler service
  `npm i @sourceloop/scheduler-service`
- Set the [environment variables](#environment-variables).
- Run the [migrations](#migrations).
- Bind the Scheduler Config to `SchedulerBindings.Config` key-

  ```typescript
  this.bind(SchedulerBindings.Config).to({
      jwtIssuer: process.env.JWT_ISSUER;
      jwtSecret: process.env.JWT_SECRET;
  });
  ```

- Add the `SchedulerComponent` to your Loopback4 Application (in `application.ts`)

  ```typescript
  // import the SchedulerComponent
  import {SchedulerComponent} from '@sourceloop/scheduler-service';
  ...
  // add Component for SchedulerComponent
  this.component(SchedulerComponent);
  ...
  ```

- Set up a [Loopback4 Datasource](https://loopback.io/doc/en/lb4/DataSource.html) with `dataSourceName` property set to
  `SchedulerDatasourceName`. You can see an example datasource [here](#setting-up-a-datasource).
- Set up a [Loopback4 Datasource](https://loopback.io/doc/en/lb4/DataSource.html) with `dataSourceName` property set to
  `AuthCacheDatasourceName`. You can see an example datasource [here](#setting-up-a-datasource).
- **Audit Logs**

  To generate audit logs for video conferencing service, you'll have to set the env var `ADD_AUDIT_LOG_MIXIN` to `true` and configure a datasource for it like below:

  ```ts
  import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
  import {juggler} from '@loopback/repository';
  import {AuditDbSourceName} from '@sourceloop/audit-log';

  const config = {
    name: 'audit',
    connector: 'postgresql',
    url: '',
    host: '',
    port: 0,
    user: '',
    password: '',
    database: '',
  };

  @lifeCycleObserver('datasource')
  export class AuditDataSource
    extends juggler.DataSource
    implements LifeCycleObserver
  {
    static dataSourceName = AuditDbSourceName;
    static readonly defaultConfig = config;

    constructor(
      @inject('datasources.config.audit', {optional: true})
      dsConfig: object = config,
    ) {
      const auditEnvConfig = {
        host: process.env.AUDIT_DB_HOST,
        port: process.env.AUDIT_DB_PORT,
        user: process.env.AUDIT_DB_USER,
        password: process.env.AUDIT_DB_PASSWORD,
        database: process.env.AUDIT_DB_DATABASE,
        schema: process.env.AUDIT_DB_SCHEMA,
      };
      Object.assign(dsConfig, auditEnvConfig);
      super(dsConfig);
    }
  }
  ```

  Configure .env of application in index.ts before exporting application like follows

  ```ts
  import * as dotenv from 'dotenv';
  dotenv.config();

  import {ApplicationConfig, SchedulerExampleApplication} from './application';
  export * from './application';
  //...
  ```

- **Using with Sequelize**

  This service supports Sequelize as the underlying ORM using [@loopback/sequelize](https://www.npmjs.com/package/@loopback/sequelize) extension. And in order to use it, you'll need to do following changes.

  - To use Sequelize in your application, add following to application.ts:

  ```ts
  this.bind(CoreSchedulerBindings.Config).to({
    useCustomSequence: false,
    useSequelize: true,
  });
  ```

  - Use the `SequelizeDataSource` in your datasource as the parent class. Refer [this](https://www.npmjs.com/package/@loopback/sequelize#step-1-configure-datasource) for more.

- Start the application
  `npm start`

### Asymmetric Token Signing and Verification

If you are using asymmetric token signing and verification, you should have auth datasource present in the service and auth redis datasource on the facade level. Example datasource file for auth database is:-

Auth DB datasource :-

```ts
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';
import {AuthDbSourceName} from '@sourceloop/core';
const DEFAULT_MAX_CONNECTIONS = 25;
const DEFAULT_DB_IDLE_TIMEOUT_MILLIS = 60000;
const DEFAULT_DB_CONNECTION_TIMEOUT_MILLIS = 2000;

const config = {
  name: 'auth',
  connector: 'postgresql',
  host: process.env.DB_HOST,
  port: process.env.DB_PORT,
  user: process.env.DB_USER,
  schema: process.env.DB_SCHEMA,
  password: process.env.DB_PASSWORD,
  database: process.env.AUTH_DB,
};

// Observe application's life cycle to disconnect the datasource when
// application is stopped. This allows the application to be shut down
// gracefully. The `stop()` method is inherited from `juggler.DataSource`.
// Learn more at https://loopback.io/doc/en/lb4/Life-cycle.html
@lifeCycleObserver('datasource')
export class AuthDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static dataSourceName = AuthDbSourceName;

  static readonly defaultConfig = config;

  constructor(
    @inject('datasources.config.auth', {optional: true})
    dsConfig: object = config,
  ) {
    if (!!+(process.env.ENABLE_DB_CONNECTION_POOLING ?? 0)) {
      const dbPool = {
        max: +(process.env.DB_MAX_CONNECTIONS ?? DEFAULT_MAX_CONNECTIONS),
        idleTimeoutMillis: +(
          process.env.DB_IDLE_TIMEOUT_MILLIS ?? DEFAULT_DB_IDLE_TIMEOUT_MILLIS
        ),
        connectionTimeoutMillis: +(
          process.env.DB_CONNECTION_TIMEOUT_MILLIS ??
          DEFAULT_DB_CONNECTION_TIMEOUT_MILLIS
        ),
      };

      dsConfig = {...dsConfig, ...dbPool};
    }

    super(dsConfig);
  }
}
```

Auth Cache Redis Datasource:-

```ts
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {AnyObject, juggler} from '@loopback/repository';
import {readFileSync} from 'fs';
import {AuthCacheSourceName} from '@sourceloop/core';

const config = {
  name: process.env.REDIS_NAME,
  connector: 'kv-redis',
  host: process.env.REDIS_HOST,
  port: process.env.REDIS_PORT,
  password: process.env.REDIS_PASSWORD,
  db: process.env.REDIS_DATABASE,
  url: process.env.REDIS_URL,
  tls:
    +process.env.REDIS_TLS_ENABLED! && process.env.REDIS_TLS_CERT
      ? {
          ca: readFileSync(process.env.REDIS_TLS_CERT),
        }
      : undefined,
  sentinels:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINELS
      ? JSON.parse(process.env.REDIS_SENTINELS)
      : undefined,
  sentinelPassword:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINEL_PASSWORD
      ? process.env.REDIS_SENTINEL_PASSWORD
      : undefined,
  role:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINEL_ROLE
      ? process.env.REDIS_SENTINEL_ROLE
      : undefined,
};

@lifeCycleObserver('datasource')
export class RedisDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static readonly dataSourceName = AuthCacheSourceName;
  static readonly defaultConfig = config;

  constructor(
    @inject(`datasources.config.${process.env.REDIS_NAME}`, {optional: true})
    dsConfig: AnyObject = config,
  ) {
    if (
      +process.env.REDIS_HAS_SENTINELS! &&
      !!process.env.REDIS_SENTINEL_HOST &&
      !!process.env.REDIS_SENTINEL_PORT
    ) {
      dsConfig.sentinels = [
        {
          host: process.env.REDIS_SENTINEL_HOST,
          port: +process.env.REDIS_SENTINEL_PORT,
        },
      ];
    }
    super(dsConfig);
  }
}
```

### Environment Variables

Do not forget to set Environment variables. The examples below show a common configuration for a PostgreSQL Database and Redis Database running locally.

```environment
NODE_ENV=dev
LOG_LEVEL=DEBUG
HOST=0.0.0.0
PORT=3000
DB_HOST=localhost
DB_PORT=5432
DB_USER=pg_service_user
DB_PASSWORD=pg_service_user_password
DB_DATABASE=schedular_db
DB_SCHEMA=public
REDIS_HOST=localhost
REDIS_PORT=6379
REDIS_URL=redis_url
REDIS_PASSWORD=redis_service_user_password
REDIS_DATABASE=redis_schedular_db
JWT_SECRET=super_secret_string
JWT_ISSUER=https://authentication.service
```

| Name                              | Required | Default Value | Description                                                                                                                        |
| --------------------------------- | -------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| `NODE_ENV`                        | Y        |               | Node environment value, i.e. `dev`, `test`, `prod`                                                                                 |
| `LOG_LEVEL`                       | Y        |               | Log level value, i.e. `error`, `warn`, `info`, `verbose`, `debug`                                                                  |
| `HOST`                            | Y        |               | Host for the service to run under, i.e. `0.0.0.0`                                                                                  |
| `PORT`                            | Y        | `3000`        | Port for the service to listen on.                                                                                                 |
| `DB_HOST`                         | Y        |               | Hostname for the database server.                                                                                                  |
| `DB_PORT`                         | Y        |               | Port for the database server.                                                                                                      |
| `DB_USER`                         | Y        |               | User for the database.                                                                                                             |
| `DB_PASSWORD`                     | Y        |               | Password for the database user.                                                                                                    |
| `DB_DATABASE`                     | Y        |               | Database to connect to on the database server.                                                                                     |
| `DB_SCHEMA`                       | Y        | `public`      | Database schema used for the data source. In PostgreSQL, this will be `public` unless a schema is made explicitly for the service. |
| `REDIS_HOST`                      | Y        |               | Hostname for the Redis server.                                                                                                     |
| `REDIS_PORT`                      | Y        |               | Port to connect to redis server.                                                                                                   |
| `REDIS_URL`                       | Y        |               | Fully composed URL for Redis connection. Used                                                                                      |
| instead of other settings if set. |
| `REDIS_PASSWORD`                  | Y        |               | Password for the redis user.                                                                                                       |
| `REDIS_DATABASE`                  | Y        |               | Database to connect to on the redis server.                                                                                        |
| `JWT_SECRET`                      | Y        |               | Symmetric signing key of the JWT token.                                                                                            |
| `JWT_ISSUER`                      | Y        |               | Issuer of the JWT token.                                                                                                           |

### Setting up a `DataSource`

Here is a sample Implementation `DataSource` implementation using environment variables and PostgreSQL as the data source.

```typescript
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';
import {SchedulerDatasourceName} from '@sourceloop/scheduler-service';

const config = {
  name: SchedulerDatasourceName,
  connector: 'postgresql',
  host: process.env.DB_HOST,
  port: process.env.DB_PORT,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_DATABASE,
  schema: process.env.DB_SCHEMA,
};

@lifeCycleObserver('datasource')
export class SchedulerDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static dataSourceName = SchedulerDatasourceName;
  static readonly defaultConfig = config;

  constructor(
    @inject(`datasources.config.${SchedulerDatasourceName}`, {optional: true})
    dsConfig: object = config,
  ) {
    super(dsConfig);
  }
}
```

Here is a sample Implementation `Cache DataSource` implementation using environment variables and Redis as the data source.

```typescript
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';

const config = {
  name: 'AuthCache',
  connector: 'kv-redis',
  url: '',
  host: process.env.REDIS_HOST,
  port: process.env.REDIS_PORT,
  password: process.env.REDIS_PASSWORD,
  db: process.env.REDIS_DB,
};

@lifeCycleObserver('datasource')
export class AuthCacheDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static dataSourceName = 'AuthCache';
  static readonly defaultConfig = config;

  constructor(
    @inject('datasources.config.AuthCache', {optional: true})
    dsConfig: object = config,
  ) {
    super(dsConfig);
  }
}
```

## Migrations

The migrations required for this service are processed during the installation automatically if you set the `SCHEDULER_MIGRATION` or `SOURCELOOP_MIGRATION` env variable. The migrations use [`db-migrate`](https://www.npmjs.com/package/db-migrate) with [`db-migrate-pg`](https://www.npmjs.com/package/db-migrate-pg) driver for migrations, so you will have to install these packages to use auto-migration. Please note that if you are using some pre-existing migrations or databases, they may be affected. In such a scenario, it is advised that you copy the migration files in your project root, using the `SCHEDULER_MIGRATION_COPY` or `SOURCELOOP_MIGRATION_COPY` env variables. You can customize or cherry-pick the migrations in the copied files according to your specific requirements and then apply them to the DB.

This migration script supports both MySQL and PostgreSQL databases, controlled by environment variables. By setting MYSQL_MIGRATION to 'true', the script runs migrations using MySQL configuration files; otherwise, it defaults to PostgreSQL. .

Additionally, there is now an option to choose between SQL migration or PostgreSQL migration.
NOTE : For @sourceloop/cli users, this choice can be specified during the scaffolding process by selecting the "type of datasource" option.

## Database Schema

![db-schema](https://github.com/sourcefuse/loopback4-microservice-catalog/blob/master/services/scheduler-service/migrations/scheduler_db_schema.png?raw=true)

## API's Details

Visit the [OpenAPI spec docs](./openapi.md)

## Feedback

If you've noticed a bug or have a question or have a feature request, [search the issue tracker](https://github.com/sourcefuse/loopback4-notifications/issues) to see if someone else in the community has already created a ticket.
If not, go ahead and [make one](https://github.com/sourcefuse/loopback4-notifications/issues/new/choose)!
All feature requests are welcome. Implementation time may vary. Feel free to contribute the same, if you can.
If you think this extension is useful, please [star](https://help.github.com/en/articles/about-stars) it. Appreciation really helps in keeping this project alive.

## Contributing

Please read [CONTRIBUTING.md](https://github.com/sourcefuse/loopback4-notifications/blob/master/.github/CONTRIBUTING.md) for details on the process for submitting pull requests to us.

## Code of conduct

Code of conduct guidelines [here](https://github.com/sourcefuse/loopback4-notifications/blob/master/.github/CODE_OF_CONDUCT.md).

## License

[MIT](https://github.com/sourcefuse/loopback4-notifications/blob/master/LICENSE)