1. Description:

This project is an Rest API, developed in JAVA using spring framework. It have the below functionality implemented on the below area.

The one listed below as 📌 are the list of are part of the excisies.

1.1 Stock

• Get the stock for provided productId 📌
• Add stock for an product
• Updated stock for an existing stock 📌

1.2 Statistic

• Get the statistic for today or lastMonth, listing TopAvailableProduct and TopSellingProduct for the given range. 📌

1.3 Product

• Adding of product
• Get all the products from backend
• Get the product and the associated stock for a given productId

1.4 Invoice

• Add invoice for an product to record sales.

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2. Technical Details:

2.1 Tools & framework:

The below are the list of tools and framework used in the project!

• Spring Boot framework
• Maven for Packaging and Build
• Java Programming language
• MySQL as backend

2.2 Key Feature to Highlight:

• Implemented cache to cache data, this is to enable to serve stock get request even if the database is offline!
• To check on 'the last change wins' problem on an concurrent request, I have implemented Etag and Version on this spring boot application.
• Pagination to get the list of top selling products and top availabile product, this was implemented as a Proof of concept (POC) only.
• Details failure cases are listed in the endpoint section below that are covered .
• Controller Advice is used to display readable error message, TODO: Other than custom exception, i have not handled using controller advice.

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3. Stock Endpoint:

The below are the endpoints that are exposed to GET PUT PATCH Stock!

3.1 GET Stock By Product Id

This endpoint will list all the stock that are available for the given ProductId. This endpoint covers the below scenarios.

Description of scenario covered:

• To enable CONCURRENT REQUEST for getting the stock for the productId. If stock is found for the productId, then populate response header with key ETAG and value for the key with VERSION column value from stock table for the given productId.
• The requested stock for the given productId will be searched from the inmemory CACHE, if available the data will be served to the user else it will be searched from the stock table.
• If there are NO STOCK AVAILABLE for the productId, then I have populated an attribute called StockMessage which has message as 'There are no stock available for this productId'.
• Check if the user have given valid productId for the stock. If it is INVALID PRODUCTID, then respond user as ErroneousJsonException with message as 'Product not found'.

3.1.1 Getting stock for valid productid

Request - Valid ProductId

GET /commercetools/api/v1/stock?productId=veg HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==

Response - Valid ProductId

Response Body

{
    "productId": "veg",
    "requestTimestamp": "2019-06-01T19:00:54.248Z",
    "stock": [
        {
            "id": "1",
            "timestamp": "2019-05-31T09:53:53.390Z",
            "quantity": 229
        }
    ]
}

Response Header

ETag: "20"

---

3.1.2 Getting stock for invalid productid

Request - InValid ProductId

GET /commercetools/api/v1/stock?productId=cake HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==

Response - InValid ProductId

{
    "message": "Invalid Request :: Reason - Product not found",
    "statusCode": "BAD_REQUEST"
}

---

3.2 Update existing stock

This endpoint will help in updating the existing stock.

Description of scenario covered:

• If user provide a invalid productId in the request JSON, then respond user as ErroneousJsonException with a message 'Invalid Request :: Reason - Product not found'.
• If user provide a invalid stockId in the request JSON, then respond user as ErroneousJsonException with a message 'Invalid Request :: Reason - Invalid stockid'.
• If user provide a timestamp for an existing stock with an earlier timestamp to update, then respond with HTTP status as 204 No Content.
• If a valid JSON request is provided. Since I have implemented cache, the cached values are refreshed so that the GET request can use the data from cache.

Special Case

For concurrent requests for updating the same stock.

• If a Stock is found for a productId, Then
  • The request HTTP header is checked for a key 'if-Match' and the value from if-Match key is validated with the current stock version. if TRUE, then
    • The stock is updated
  • else, http status precondition failed exception is thrown to user.

3.2.1 Update stock for Invalid JSON (One Sample Request)

Request

POST /commercetools/api/v1/stock/update HTTP/1.1
Host: localhost:8080
Content-Type: application/json
If-Match: 20
Authorization: Basic dXNlcjpwYXNzd29yZA==
{
	"id":"100",
	"productId": "veg",
	"timestamp": "2019-05-30T09:53:53.390Z",
	"quantity": 229
}

Response

{
    "message": "Invalid Request :: Reason - Invalid stockid",
    "statusCode": "BAD_REQUEST"
}

---

3.2.2 Update stock for Valid JSON (One Sample Request)

Request

POST /commercetools/api/v1/stock/update HTTP/1.1
Host: localhost:8080
Content-Type: application/json
If-Match: 20
Authorization: Basic dXNlcjpwYXNzd29yZA==
{
	"id":"1",
	"productId": "veg",
	"timestamp": "2019-05-31T10:53:53.390Z",
	"quantity": 229
}

Response

{
    "productId": "veg",
    "requestTimestamp": "2019-06-01T21:31:25.167Z",
    "stock": [
        {
            "id": "1",
            "timestamp": "2019-05-31T10:53:53.390Z",
            "quantity": 229
        }
    ]
}

---

3.3 Add new stock: (Additional Feature)

This endpoint is only to add a new stock. I have not added any validation for this endpoint in particular.

Request

PUT /commercetools/api/v1/stock/add HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==
{
	"productId": "drinks",
	"timestamp": "2019-05-29T22:55:01.754Z",
	"quantity": 98
}

Response

{
    "productId": "drinks",
    "requestTimestamp": "2019-05-31T18:43:41.776Z",
    "stock": [
        {
            "id": "2",
            "timestamp": "2019-05-29T22:55:01.754Z",
            "quantity": 98
        }
    ]
}

---

4. Statistic Endpoint

This endpoint list the top 3 available stock and top 3 sales products for the users.

4.1 Getting Statistic

Description of scenario:

• Check if the User has given a valid time (today or lastMonth). If its invalid time, then respond user as InvalidStatisticTimeException with message as 'Invalid time for statistics, Please provide a valid value'.
• If there are no stock available for the given time, then I have populated an attribute called TopAvailableProductMessage which has message as "There are no product that was available for provided 'time'".
• If there are stock available but less than 3 for the given time, then I have populated an attribute called TopAvailableProductMessage which has message as "There are only 'count of available stock' product that had sales for 'time'".
• If there are no sales available for the given time, then I have populated an attribute called TopSellingProductsMessage which has message as 'There are no product that was available for provided 'time'".
• If there are stock sales but less than 3 for the given time, then I have populated an attribute called TopSellingProductsMessage which has message as 'There are only 'count of sales' product that had sales for 'time'".
• Group topSellingProduct for the given time, based on the productId & sum the total sales and return to the user.

Request

GET /commercetools/api/v1/statistics?time=lastMonth HTTP/1.1
Host: localhost:8080
Authorization: Basic dXNlcjpwYXNzd29yZA==

Response

{
    "requestTimestamp": "2019-06-01T21:44:56.073Z",
    "range": "lastMonth",
    "topAvailableProductMessage": "There are only 2 product that had available for lastMonth",
    "topAvailableProducts": [
        {
            "id": "1",
            "timestamp": "2019-05-31T10:53:53.390Z",
            "productId": "veg",
            "quantity": 229
        },
        {
            "id": "2",
            "timestamp": "2019-05-29T22:55:01.754Z",
            "productId": "drinks",
            "quantity": 98
        }
    ],
    "topSellingProductsMessage": "There are no sales available on any product for lastMonth"
}

---

5. Product Endpoint: (Additional Feature)

The below are the endpoints that are exposed to GET PUT products!

5.1 GET Product

This endpoint gets all the products from database.

Request

GET /commercetools/api/v1/products HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==

Response

[
    {
        "id": 1,
        "productId": "cake",
        "stock": [
            {
                "id": "2",
                "quantity": 100,
                "timestamp": "2019-05-29T22:55:01.754Z"
            }
        ],
        "invoice": [
            {
                "id": "1",
                "quantity": 99,
                "timestamp": "2019-05-29T22:55:01.754Z"
            }
        ]
    }
]

---

5.2 PUT Product

This endpoint allows the user to add a new product.

Request

PUT /commercetools/api/v1/product/add HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==
{
	"productId": "drinks"
}

Response

<<Auto Generated id>>

---

5.3 GET Product by productId

This endpoint gets the product for a given productId from database.

Request

GET /commercetools/api/v1/product/stock?productId=drinks HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==

Response

{
    "productId": "drinks",
    "requestTimestamp": "2019-05-31T12:09:27.652Z",
    "stock": []
}

---

6. Invoice Endpoint

To add sales for a product, I have added this endpoint so that we can add sales!

6.1 Add Invoice:

Description of scenario covered:

• Check if the productId exist for the request invoice that needs to be added, if invalid productId then respond user with message "Error while saving data - Product not found".

Request

PUT /commercetools/api/v1/invoice/add HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Authorization: Basic dXNlcjpwYXNzd29yZA==
{
	"productId": "veg",
	"timestamp": "2019-05-29T22:55:01.754Z",
	"quantity": 99
}

Response

{
    "id": "1",
    "quantity": 99,
    "timestamp": "2019-05-29T22:55:01.754Z"
}

7. Extract Feature enabled:

The below are the add-on as feature.

• Swagger-UI
• Docker

7.1 Swagger

If you are running this application localy, then the swagger UI can be accessed via the below url.

http://localhost:8080/swagger-ui.html#/

7.2 Run as Docker Container

I have built a docker image and the same is available in dockerhub. Run the below comment to run the docker image as container.

docker run -p 8080:8080 -t rasmivan/commercetools:1.0