**Course Title:** Mastering Ruby on Rails: Building Scalable Web Applications **Section Title:** Background Jobs and Task Scheduling **Topic:** Implement background jobs for sending emails or processing data in a Rails application.(Lab topic) **Introduction:** In this topic, we will explore the concept of background jobs in Rails and how to implement them for sending emails or processing data. Background jobs allow your application to perform tasks asynchronously, freeing up the main thread and improving overall performance. In this lab, we will use the Sidekiq gem to implement background jobs for sending emails. **What are Background Jobs?** Background jobs are tasks that are executed outside of the main thread of your application. They allow your application to perform tasks asynchronously, without blocking the main thread. This is particularly useful for tasks that take a long time to complete, such as sending emails or processing large amounts of data. **Why Use Background Jobs?** Using background jobs can improve the performance and scalability of your application. By executing tasks asynchronously, you can: * Improve responsiveness: By not blocking the main thread, your application can respond quickly to user input. * Increase throughput: By executing tasks in the background, you can process large amounts of data without slowing down your application. * Reduce latency: By sending emails or processing data asynchronously, you can reduce the latency associated with these tasks. **Implementing Background Jobs with Sidekiq** In this lab, we will use the Sidekiq gem to implement background jobs for sending emails. Sidekiq is a popular gem for background jobs in Rails, and it provides a simple and efficient way to execute tasks asynchronously. **Step 1: Add Sidekiq to Your Application** To add Sidekiq to your application, run the following command: ```bash gem add sidekiq ``` **Step 2: Configure Sidekiq** To configure Sidekiq, create a `config/sidekiq.yml` file with the following content: ```yml production: url: http://localhost:9292 retry: true queue: default ``` This configuration tells Sidekiq to connect to the Rails server at `http://localhost:9292`, and to retry failed jobs. **Step 3: Create a Background Job** To create a background job, create a new file called `app/jobs/send_email_job.rb` with the following content: ```ruby class SendEmailJob < ApplicationJob queue_as :default def perform(email, name) # Send an email using ActionMailer Mailer.send_email(email, name).deliver_now end end ``` This job takes two arguments: `email` and `name`. It uses ActionMailer to send an email to the specified address. **Step 4: Create a Job Class** To create a job class, create a new file called `app/services/send_email_service.rb` with the following content: ```ruby class SendEmailService def initialize(email, name) @email = email @name = name end def send_email SendEmailJob.perform_async(@email, @name) end end ``` This service class takes two arguments: `email` and `name`. It creates a new `SendEmailJob` instance and calls its `perform_async` method. **Step 5: Use the Job Class** To use the job class, create a new file called `app/controllers/sessions_controller.rb` with the following content: ```ruby class SessionsController < ApplicationController def create # Create a new user session user = User.find_by(email: params[:email]) if user # Create a new SendEmailService instance service = SendEmailService.new(user.email, user.name) # Call the send_email method service.send_email end end end ``` This controller creates a new user session and calls the `send_email` method on the `SendEmailService` instance. **Conclusion:** In this lab, we implemented background jobs for sending emails using the Sidekiq gem. We created a new job class, a job service class, and used the service class in a controller. By executing the job asynchronously, we improved the performance and scalability of our application. **Exercise:** Implement background jobs for processing data in a Rails application. Create a new job class, a job service class, and use the service class in a controller. Use the `perform_async` method to execute the job asynchronously. **External Links:** * Sidekiq documentation: <https://github.com/mperlin/sidekiq> * ActionMailer documentation: <https://api.rubyonrails.org/v6.1.4/classes/ActionMailer.html> **Leave a comment or ask for help:** If you have any questions or need further assistance, please leave a comment below.