Country Service Documentation

After reading this document you will be able to set up the development environment and run the project. The repository consists of two folders:

• countryservice : contain Java codes for back-end side
• countryservice-front : contain HTML, JavaScript codes for front-end side.

Pre-requirement

• Maven - https://maven.apache.org/install.html
• Java 17 - https://www.oracle.com/java/technologies/downloads/#java17
• Environment Variables : This variable should be defined in your OS, Cloud provider dashboard or in your IDE before running the project.

COUNTRY_SERVICE_LOG_PATH : Indicate logs' path

COUNTRY_SERVICE_HTTP_PORT : Indicate micro-service's HTTP port

these environment variables make a straightforward way to containerize the micro-service

Back-end side

When the Spring container starts the micro-service try to fetch countries' data once and store it on the H2 in-memory database, Therefore for each request the micro-service does not gather data from the remote source. If the micro-service received a request for countries' data and the database was empty because of network failure and so on, an event initiate to re-fetch data again.

Maven dependencies:

• spring-boot-starter-web : For providing HTTP Rest APIs
• spring-boot-starter-log4j2 : For logging system.
• spring-boot-starter-test: For test purposes
• json-simple: A library for praseing JSON data.
• spring-boot-starter-data-jpa: Spring JPA for storing data and working with database
• h2: Is an embedded in-memory database for storing countries' data

Rest APIs

GET /countries/

response:
          {
                   "countries": [
                             {
                                       "name": "Finland",
                                       "country_code": "FI"
                             },
                             ...
                   ]
          }

GET /countries/{name}

response:

      {

               "name": "Finland",

               "country_code": "FI",

               "capital": "Helsinki",

               "population": 5491817,

               "flag_file_url": "<url to the flag file>"

      }

Logging system

The application events are logged on a file-size base rotating policy and this policy can be changed. the logs will be stored on the path which is defined in COUNTRY_SERVICE_LOG_PATH Read more about log4j configuration.

Services

• JsonProcessor : Recieve JSON data as a string and convert it to a java object [ CountryDTO ]
• CountryServiceLogger : Getting general Output classes and log error, exception or important event
• CountryServiceEventListenerImpl : An event listener for re-fetching counries' data from remote source
• CountryServiceCordinator : Act as a coordinator and utilize all capabilities of other services like JsonProcessor, CountryServiceLogger, and CountriesDataStore to gather, convert and store countries' data.
• CountriesDataStore : Implement the data layer. its responsibility is storing, fetching, and converting data.

Data Layer

• CountryRepository : A repository for database operations which use CountryEntity to persist fetched data.

Testing

Some unit test is written in the test folder.

• DataLayerTests : Contains test cases related to the data layer for inserting and fetching data.
• FetchingAndProcessingCountriesDataTests : Testing fetching and processing JSON data related services

We can add integration or end-to-end test, as well as different test cases to reach a better test coverage.

Front-end

To run this simple Front-end application you just need a browser that can run JavaScript code. Do not worry most modern browsers do it. Just open index.html and type the country's name in the text box.

You can define the address of the country service Rest API address by COUNTRY_SERVICE_API_URL constant in main.js