realtime-statistics

Spring boot project to show continuous statistics for last 'n' transactions

Technology used

• Spring boot : Web application
• Maven : Building project
• Java 8 : programming language
• Swagger : RESTful Documentation

Web Application configuration

• Web Application is running on port 8080
• You can change the configuration in application.properties

Steps to run the project

Prerequisite

• Maven
• Java 8 or higher

Name of the server

SaM (Statistics Machine) 

NOTE: Just for fun, you will find this name in the loggers at debug layer.

Start the application

Through following command:

mvn clean install spring-boot:run 

Maven will install all the dependencies and followed by run the spring boot application

To view the RESTful APIs in the application

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

Architectural points and Terminologies used in the project

O(1) for time and space complexity

• Calculation is made in constant time by looking into map of Statistics Cache (in-memory map) and only combining already calculated statistics to provide statistics summary for /transaction, which means method runs with O(1) complexity

• Note:

  • If previously inserted entry is outdated then it will be overwritten by new incoming one(s).
  • If no new transaction entry is received for that second then it'll be simply ignored during retrieval.

Trying out and documentation for RESTful APIs

Swagger is already integrated and can be used for using API instead of curl.

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

Modularise

For the time being I have modularise the project on package level. Later we can also modularise in maven modules.

Event driven architecture

To communicate when transaction and statistics, spring-framework's application event publisher is used.

Developer should take ownership of code, hence testing is IMPORTANT!

There are two type of tests written within the project:

1. Integration Test (REST Layer Classes)
2. Unit Testing (Service Layer Classes)

To check the result of the test, please throw following command in the terminal:

> mvn clean install

Comments in code

Entire code styling is influenced by Clean Code principle - Robert Martin Which says 'Truth can only be found in one place: the code’. So you may not found any comments anywhere in the project. Keeping in mind that git can be used to versioning of file and method, class names should be kept as self explanatory.

However, if you need comments on each file. I can do that too.

Design principles used in Project :

• SOLID (single responsibility, open-closed, Liskov subsitution, interface segragation, dependency inversion) principle
• Composition over inheritance
• DRY(Don’t repeat yourself)
• KISS(Keep it simple, stupid)
• Event based programming
• and some experience principle ;)