System Design: Electoral System

This question requires you to create a high-level architecture for a voting system. The hiring manager will be assessing your grasp of system design principles, including data modeling, concurrency, load balancing, fault tolerance, and more. A crucial aspect will be identifying the assumptions you have regarding the voting system's usage. Is it intended for a small local election or for a national vote? Be sure to state any assumptions clearly before you begin presenting your solution. Additionally, take into account constraints such as vote uniqueness, the collection and presentation of voting data, scalability, security, and data integrity.

If the goal is to establish a national online voting system, we can approach it in the following manner. Initially, we should implement a distributed database to manage voter information. This setup can handle a significant number of simultaneous users, enabling distinct voters to access the system concurrently from various locations. Examples of suitable databases include MongoDB and Cassandra. For the application layer, adopting a microservices architecture will offer the scalability and fault tolerance we need. Each service can maintain its own database. Voters could interact with a dedicated voting microservice, while another microservice could handle identity verification. To guarantee the uniqueness of votes and prevent any vote tampering, the application should first verify a user's identity. Once their identity is authenticated and it is confirmed that they have not yet voted, they will be permitted to cast their vote. After the individual completes the voting process, the system will mark them as having voted, thereby blocking any further votes. Lastly, for the frontend, we can employ lightweight, reactive frameworks like React or Vue.js, ensuring prompt and smooth updates to the client interface.

In a different scenario, imagine we are developing an internal voting system for a small corporate setting to facilitate employee elections. On the database front, we could opt for a relational database management system like SQL, as the system is relatively compact and the data is fairly organized. For the application layer, a monolithic design would be appropriate given the system's small scale. An Express.js and Node.js application would be adequate for managing multiple incoming user requests. The front end could be created using JavaScript frameworks such as Angular.js, offering a user-friendly interface for casting votes. The system would first verify the employee's identity and determine whether they have already voted. Once a vote is submitted, the system will prevent the user from voting again. The results can then be compiled and displayed in real-time, promoting transparency in the voting process. Ultimately, the key principle is that each voter is allowed to cast their vote only once to ensure fairness and accuracy in the results. Proper authentication and session tracking are essential for this function to operate effectively.