shiweicc / atelier-system-design-qna-service

Atelier Q&A | Back-end services for e-commerce site

I worked with other two software engineers to rebuild the back-end API service from a monolithic to service-oriented microservices to support our existing e-commerce application in this project. The service I built was scaled to meet the demands of production traffic, which is 5000rps with < 1s response time with a 0% error rate.

Technologies used

Backend Development: Node.js, Express, Postgres, NGINX
Deployment: AWS EC2, AWS Images
Testing: Jest, SuperTest, K6, Loader.io, New Relic

Table of Contents

• System Design
• Usage
• Installation

System Design

Database Design

Architecture

Stress Test Results via Loader.io

Usage

List Questions

GET /qa/questions Retrieves a list of questions for a particular product. This list does not include any reported questions.

Parameters

Parameter	Type	Description
product_id	integer	Specifies the product for which to retrieve questions.
page	integer	Selects the page of results to return. Default 1.
count	integer	Specifies how many results per page to return. Default 5.

Response

Status: 200 OK

{
  "product_id": "5",
  "results": [{
        "question_id": 37,
        "question_body": "Why is this product cheaper here than other sites?",
        "question_date": "2018-10-18T00:00:00.000Z",
        "asker_name": "williamsmith",
        "question_helpfulness": 4,
        "reported": 0,
        "answers": {
          "68": {
            "id": 68,
            "body": "We are selling it here without any markup from the middleman!",
            "date": "2018-08-18T00:00:00.000Z",
            "answerer_name": "Seller",
            "helpfulness": 4,
            "photos": []
            // ...
          }
        }
      },
      {
        "question_id": 38,
        "question_body": "How long does it last?",
        "question_date": "2019-06-28T00:00:00.000Z",
        "asker_name": "funnygirl",
        "question_helpfulness": 2,
        "reported": 0,
        "answers": {
          "70": {
            "id": 70,
            "body": "Some of the seams started splitting the first time I wore it!",
            "date": "2019-11-28T00:00:00.000Z",
            "answerer_name": "sillyguy",
            "helpfulness": 6,
            "photos": [],
          },
          "78": {
            "id": 78,
            "body": "9 lives",
            "date": "2019-11-12T00:00:00.000Z",
            "answerer_name": "iluvdogz",
            "helpfulness": 31,
            "photos": [],
          }
        }
      },
      // ...
  ]
}

Answers List

Returns answers for a given question. This list does not include any reported answers.

GET /qa/questions/:question_id/answers

Parameters

Parameter	Type	Description
question_id	integer	Required ID of the Question requested
page	integer	Selects the page of results to return. Default 1.
count	integer	Specifies how many results per page to return. Default 5.

Response

Status: 200 OK

{
  "question": "1",
  "page": 0,
  "count": 5,
  "results": [
    {
      "answer_id": 8,
      "body": "What a great question!",
      "date": "2018-01-04T00:00:00.000Z",
      "answerer_name": "metslover",
      "helpfulness": 8,
      "photos": [],
    },
    {
      "answer_id": 5,
      "body": "Something pretty durable but I can't be sure",
      "date": "2018-01-04T00:00:00.000Z",
      "answerer_name": "metslover",
      "helpfulness": 5,
      "photos": [{
          "id": 1,
          "url": "urlplaceholder/answer_5_photo_number_1.jpg"
        },
        {
          "id": 2,
          "url": "urlplaceholder/answer_5_photo_number_2.jpg"
        },
        // ...
      ]
    },
    // ...
  ]
}

Add a Question

Adds a question for the given product

POST /qa/questions

Parameters

Parameter	Type	Description
product_id	integer	Required ID of the Product to post the question for

Body Parameters

Parameter	Type	Description
body	text	Text of question being asked
name	text	Username for question asker
email	text	Email address for question asker

Response

Status: 201 CREATED

Add an Answer

Adds an answer for the given question

POST /qa/questions/:question_id/answers

Parameters

Parameter	Type	Description
question_id	integer	Required ID of the question to post the answer for

Body Parameters

Parameter	Type	Description
body	text	Text of question being asked
name	text	Username for question asker
email	text	Email address for question asker
photos	[text]	An array of urls corresponding to images to display

Response

Status: 201 CREATED

Mark Question as Helpful

Updates a question to show it was found helpful.

PUT /qa/questions/:question_id/helpful

Parameters

Parameter	Type	Description
question_id	integer	Required ID of the question to update

Response

Status: 204 NO CONTENT

Report Question

Updates a question to show it was reported. Note, this action does not delete the question, but the question will not be returned in the above GET request.

PUT /qa/questions/:question_id/report

Parameters

Parameter	Type	Description
question_id	integer	Required ID of the question to update

Response

Status: 204 NO CONTENT

Mark Answer as Helpful

Updates an answer to show it was found helpful.

PUT /qa/answers/:answer_id/helpful

Parameters

Parameter	Type	Description
answer_id	integer	Required ID of the answer to update

Response

Status: 204 NO CONTENT

Report Answer

Updates an answer to show it has been reported. Note, this action does not delete the answer, but the answer will not be returned in the above GET request.

PUT /qa/answers/:answer_id/report

Parameters

Parameter	Type	Description
answer_id	integer	Required ID of the answer to update

Response

Status: 204 NO CONTENT

Installation

1. Fork the project and clone to your local repository
2. To start server, run npm run start
3. Test by typing http://localhost:3000/qa/questions in the Postman to see the response
4. To run tests, run npm run test