Implementation details

Subjekt library

The library was developed using Kotlin Multiplatform, allowing the code to target both the JVM and JavaScript. To achieve this, in order to minimize the amount of code that is platform-specific, the library was developed using as many already existing multiplatform libraries as possible.

• Kotlin serialization: multiplatform library that allows to serialize and deserialize objects in a platform-independent way. The JSON module was used to parse and serialize JSON files.

• YamlKt: utility multiplatform library that allows to parse and serialize YAML files. It must be used in conjunction with Kotlin serialization.

• ANTLR: this library is JVM-based, and therefore its usage is limited to the JVM target. Instead of using it, a fork by Strumenta was used, which is a multiplatform version of the library.

Particular attention was given to the development of the public API of the library. The Javascript exporting system required to invest time in the definition of the public side of the library, sometimes using dynamic types to bypass un-exportable types.

In addition to the main entities of the domain, the library entry point is the Subjekt class, which generates a Subjekt instance from a YAML or JSON string. Note: files are not supported to avoid platform-specific code.

Auth and API services

Node.js and Express were used to develop both the RESTful services (i.e. auth and api). TypeScript was employed to enhance code maintainability.

In details, the authentication service was implemented using JWT (JSON Web Tokens) to ensure secure and stateless user authentication.

MongoDB was used as the primary database for storing application data, while Redis was employed for rate limiting storage. Additionally, a validation handler has been applied to specific routes to ensure data integrity and enforce input validation.

To enhance API usability and maintainability, route documentation has been provided using Swagger, enabling interactive exploration and testing of endpoints.

A simple role-based access control (RBAC) has been implemented to differentiate between administrative and regular user privileges. Access control rules ensure that only authorized users can perform specific actions, enhancing security and maintaining data integrity.

Jest was used as the testing framework.

Frontend application

The frontend service was developed using Vue.js, a popular JavaScript framework, with TypeScript. The application is a simple web application that allows to authenticate users and manage sources through which generate Subjekt results.

The application uses the axios library to perform HTTP requests to the backend services (auth and API). To manage authentication and authorization, we used interceptors to intercept requests and responses in order to perform checks on the JWT token of the user's session.

To handle the state of the application and encapsulate the API calls, we used the Pinia library, which is a Vue.js state management library that allows to create stores and actions in a simple way.