Tradies

Welcome to my Marketplace or CtoC ecommerce application!
Tradies is where people go to buy and sell items! I originally built to help friends buy and sell items locally with simple user interface and to learn building a website from scratch. This was my first scalable, full-stack RoR application.

Tech Stack

• Ruby on Rails 5 application hosted on Heroku.
• Front-end: Bootstrap 3, jQuery for animations, Select2
• Back-end: PostgreSQL in Development, Staging, and Production stages.
• Mail Server: SendGrid
• Object Storage server: Amazon S3 used to store profile images.
• Asynchronous Processing (with app server): Sidekiq with Redis applicaiton server
• Search: Bonsai Elasticsearch
• In-app Messaging: Mailboxer
• In-app transaction: WePay
• analytics: Google analytics
• App Monitoring: New Relic

Features

The app requires authentication to access. Authentication is executed with email verification (emails sent by SendGrid) and mailers.

Asynchronous/Background Processing
All the mailing are handled by queue implemented in Redis Server(Sidekiq sits on top of it) and de-queued consecutively.
There is definitely a bottleneck which will be discussed later.

Upon login, you can search using the search bar at the top:

• Handling search terms
• Handling search filters (category and location)

  def beautiful_search_url
  # check this function in the link above
  end

• in my Post.rb, I built this function to merge attributes into one for search query.

  def search_data
  attributes.except(:state, :content).merge(
    category_titles: categories.map(&:title)
  )
  end

  Messaging
• Users can message between each other.
• Users will be notified via emails that they received messages.
  

WePay payment

• Used WePay API to handle transactions

  # creates a checkout object using WePay API for this user
  ...
  def create_checkout(redirect_uri)
  price = self.price
  app_fee = tradies_app_fee(price)
  params = {
    :account_id => self.user_wepay_account_id,
    :short_description => "item sold by #{self.user_name}",
    :type => :goods,
    # :auto_release => false,
    :currency => 'USD',
    :amount => price,
    :fee => {
        :app_fee => app_fee,
        :fee_payer => 'payee'
    },
    :hosted_checkout => {
        :mode  => 'iframe',
        :redirect_uri => redirect_uri
    }
  }
  ...
  ...

  How my backend works

  My database schema design
  

Testing

• Used assertion tests and fake users.
• If I were to re-do this project, I would’ve used more unit tests and make them more reusable between pages.

Scalability

1) Bottleneck:

• With my current implementation, whenever the web and app servers exceeded their memory and RAM limits, Heroku automatically adds more resources to my servers or increasing Dyno size. However, this kind of approach or vertical scaling is not a good solution if this site is experiencing an exponential growth because it is 1) not cost-efficient and 2) will eventually run out of resources.

Solution:

• Horizontal Scaling:
  Instead of adding more resources, add additional servers to handle traffic. Heroku has this feature like adding more dynos at the same or smaller sizes. If I were not to use Heroku, I would have to use load balancers and handle traffic by delivering request to the server that is not currently busy (called High Availability LB).

2) Bottleneck:

• My implementation for background processing w/ Redis server is that I am currently using queue to handle sending emails. There exists a single point of failure where it just stops working. In order to prevent this, you can add LB or just implement like the solution above.

Conclusion

If I do this project again, I will definitely build better automated tests to find any bugs that I would encounter. I think I did not use my time effectively during development. Also, I will definitely have the features that I want to implement written down and create a plan before dive into coding. Since this was my first time building an application in such scale, I did not have a good plan but had a determination and perseverance to complete. Definitely, I sometimes felt like I want to give up but I pushed myself to finish this project.
I have learned a lot from this project which include but not limited to web architecture, scalability, and building something from the scratch. I forgot to mention this but don’t try to do everything by yourself:)

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MIT License