# Task Scheduling

ExpressWebJs task scheduler helps you manage scheduled tasks on your server. It allows you to define your command schedule within your application. When using the scheduler, only a single cron entry is needed on your server. Your task schedule is defined in the App/Console/Kernel.ts file’s schedule method.

# Define Schedules

The schedule method in the App/Console/Kernel.ts class. Let’s take a look at the closure scheduler example which makes use of scheduler call method. Within the closure, we will just console.log a string.

”use strict”

import scheduler from "expressweb-scheduler-ts";

class Kernel{
    /**
     * The Maker commands provided by your application.
     *
     * @var array
     */
    static commands () {
        return[
            //
        ]
    };

    /**
     * Define the application's command schedule.
     *
     * @return void
     */
    static schedule()
    {
        scheduler.call(()=> {
            console.log(‘running a closure scheduler’)
        }).daily().run();
    }
}

 
        Copied!
    

# Scheduling Maker Commands

In addition to scheduling closures, you may also schedule Maker commands. You can do this by using the scheduler command method to schedule a Maker command using the command’s name(signature) while adding the namespace in the commands method

”use strict”

import scheduler from "expressweb-scheduler-ts";

class Kernel{
    /**
     * The Maker commands provided by your application.
     *
     * @var array
     */
    static commands () {
       return ["App/Console/Commands/SendMail_command.js"];
    };

    /**
     * Define the application's command schedule.
     *
     * @return void
     */
    static schedule()
    {
        scheduler.command(‘sendMail’).daily().run();
    }
}

 
        Copied!
    

# Schedule Frequency Options

We've taken time to review few ways on how you may configure a task to run at specified intervals. However, there are many more task schedule frequencies that you may assign to a task: Check below for fields and values for cron methods and other available methods.

Allowed fields in cron method

# ┌────────────── second (optional)
# │ ┌──────────── minute
# │ │ ┌────────── hour
# │ │ │ ┌──────── day of month
# │ │ │ │ ┌────── month
# │ │ │ │ │ ┌──── day of week
# │ │ │ │ │ │
# │ │ │ │ │ │
# * * * * * *
 
        Copied!
    

These methods may be combined with additional constraints to create even more finely tuned schedules that only run on certain days of the week. For example, you may schedule a command to run weekly on Monday:

// Run once per week on Monday ...
scheduler
  .call(() => {
    //
  }).weekly().mondays().run();

// Run hourly on weekdays...
scheduler.command("foo").weekdays().hourly().run();
 
        Copied!
    

# Day Constraints

The days method may be used to limit the execution of a task to specific days of the week. For example, you may schedule a command to run hourly on Sundays and Wednesdays:

scheduler.command('SendEmail').hourly().days([0, 3]).run();
 
        Copied!
    

# Truth Test Constraints

The when method may be used to limit the execution of a task based on the result of a given truth test. In other words, if the given closure returns true, the task will execute as long as no other constraining conditions prevent the task from running:

scheduler.command('SendEmail').daily().when(()=> {
    return true;
}).run();
 
        Copied!
    

# Running The Scheduler

Now that we have learned how to define scheduled tasks, let's discuss how to actually run them on our server. The run-schedule Maker command will evaluate all of your scheduled tasks and determine if they need to run based on the server's current time.

 ts-node maker run-schedule
 
        Copied!