Scheduled Job - Job Handler

Overview

This section shows how to create helper Logger class to create log events and Job Handler that would be executed by the Scheduled Job.

Steps

Logger

1. Right click on the scheduled-job-project project and select New → TypeScript Service.
2. Enter Logger.ts for the name of the TypeScript Service.

3. Replace the content with the following code:

   import { update } from "sdk/db";
   
   export enum LogDataSeverity {
       INFO = 'Info',
       WARNING = 'Warning',
       ERROR = 'Error'
   }
   
   export interface LogData {
       readonly date: Date;
       readonly severity: LogDataSeverity;
       readonly message: string;
   }
   
   export class Logger {
   
       public static log(logData: LogData) {
           Logger.saveLogEvent(logData);
   
           const message = `---> [${logData.severity}] [${Logger.toDateString(logData.date)}]: ${logData.message} <---`;
           switch (logData.severity) {
               case LogDataSeverity.INFO:
                   console.info(message);
                   break;
               case LogDataSeverity.WARNING:
                   console.warn(message);
                   break;
               case LogDataSeverity.ERROR:
                   console.error(message);
                   break;
           }
       }
   
       private static saveLogEvent(logData: LogData) {
           const sql = `insert into LOG_EVENTS ("LOG_SEVERITY", "LOG_MESSAGE", "LOG_TIMESTAMP") values (?, ?, ?)`;
           const queryParameters = [logData.severity, logData.message, logData.date];
   
           update.execute(sql, queryParameters, null);
       }
   
       private static toDateString(date: Date): string {
           return `${date.toLocaleDateString()}; ${date.toLocaleTimeString()}`;
       }
   }
   

db/update

Take a look at the db/update documentation for more details about the API.

Logger

1. Right click on the scheduled-job-project project and select New → JavaScript ESM Service.
2. Enter handler.mjs for the name of the JavaScript Service.

3. Replace the content with the following code:

   import { Logger, LogDataSeverity } from './Logger';
   
   const logData = [{
       date: new Date(),
       severity: LogDataSeverity.INFO,
       message: 'Success feels so good!'
   }, {
       date: new Date(),
       severity: LogDataSeverity.INFO,
       message: 'You made it!'
   }, {
       date: new Date(),
       severity: LogDataSeverity.WARNING,
       message: 'Open Sesame!'
   }, {
       date: new Date(),
       severity: LogDataSeverity.WARNING,
       message: 'Password updated!'
   }, {
       date: new Date(),
       severity: LogDataSeverity.ERROR,
       message: 'Welcome to the dark side!'
   }, {
       date: new Date(),
       severity: LogDataSeverity.INFO,
       message: 'So glad you are back!'
   }];
   
   const randomIndex = Math.floor(Math.random() * logData.length);
   
   Logger.log(logData[randomIndex]);
   

4. Navigate to the Database Perspective to check that there is a record in the LOG_EVENTS table.

Save & Publish

Saving the file will trigger a Publish action, which will build and deploy the JavaScript and TypeScript services. The handler.mjs service would be executed by the Preview view. As it's expected to be executed by a Scheduled Job and not by HTTP Request nothing would be displayed in the Preview view, however the log event data would be insterted into the LOG_EVENTS table.

JavaScript ESM Handler

At the time of writing the tutorial, it was not possible to create a TypeScript handler for the Scheduled Job.

Next Steps

Section Completed

After completing the steps in this tutorial, you would have:

• Job Handler and Logger class to create log events.
• At least one record in the LOG_EVENTS table.

Continue to the Job Definition section to create a Scheduled Job, that would trigger the Job Handler.

Note: The complete content of the Scheduled Job tutorial is available at: https://github.com/dirigiblelabs/tutorial-scheduled-job-project