Json String Comparator

This is a demo Spring Boot application in order to compare 2 JSON Strings.

Requirements

Provide 2 http endpoints that accepts JSON base64 encoded binary data on both endpoints.

<host>/v1/diff/<ID>left and <host>/v1/diff/<ID>right
The provided data needs to be diff-ed and the results shall be available on a third endpoint.

<host>/v1/diff/<ID>
The results shall provide the following info in JSON format
- If equal return that
- If not of equal size just return that
- If of same size provide insight in where the diffs are, actual diffs are not needed. So mainly offsets + length in the data

Must haves

Solution written in Java
Internal logic shall be under unit test
Functionality shall be under integration test
Documentation in code
Clear and to the point readme on usage

Solution

Within this requirement, a new Spring Boot application created from scratch.

The main purpose of this demo application is to retrieve JSON strings from "/left" and "/right" endpoints, insert these data into local database and return JSON result by comparing them.

JSON Format

Client requests should be in JSON format. If not, then "415 Unsupported Media Type" exception will be thrown.

JSON format - Sample JSON Request:

{
  "content": "Sample JSON content to compare"
}

Application will return JSON responses for each request and generate different JSON content for each request of Success and Failure requests.

JSON format - Success Insertion Request:

{
  "error": false,
  "message": "Inserted successfully."
}

JSON format - Sample Failure Request:

{
  "error": true,
  "message": "Invalid JSON found! Error: Unrecognized token 'content': was expecting (JSON String, ..."
}

JSON format - Sample Success Request:

{
  "error": false,
  "message": "Objects are equal"
}

JSON format - Sample Success Request with Differences:

{
  "error": false,
  "message": "Execution successful.",
  "Differences": [
    {
      "offset": 22,
      "left char": 5,
      "right char": 6
    }
  ]
}

Usage

An executable war file created and placed under project source folder /target directory. In order to execute module and start web server, run below command in terminal.

$ java -jar JsonStringComparator.war

While application is running, typing CTRL + C in terminal will halt the server and stop execution of application.

Service will run and can be available in below url: http://localhost:8080/v1/diff/1

In first run of application, default JSON response will be as:

{
  "error": false,
  "message": "Both objects are NULL"
}

Testing

As a testing tool Postman is highly recommended to be used for making HTTP requests.

Internal logic is under unit test which is available in classes of FakeJsonObjectDaoImplTest, JsonComparatorTest and JsonResponseCreatorTest.

Functionality is under integration test which is available in classes of RestControllerTest and JsonObjectServiceTest.

Testing insertion

Steps;

Go to /target directory
Run application via command line: $ java -jar JsonStringComparator.war

Start Postman and create http request with below characteristics

Request type URL

POST http://localhost:8080/v1/diff/1/left

BODY Media Type

{“content": "Sample JSON content to compare”} JSON
Send request and check if execution is successful for insertion.

Request type	URL
POST	http://localhost:8080/v1/diff/1/left

BODY	Media Type
`{“content": "Sample JSON content to compare”}`	JSON

{ "error": false, "message": "Inserted successfully." }

Testing invalid JSON

If invalid JSON data is passed, then application will return a message as shown below.

Testing comparison (Success)