20+ Wells Fargo Senior Software Engineer Interview Questions and Answers

Answering questions on .NET Core, Razor engine, and Angular

• Implemented dependency injection in .NET Core using built-in DI container or third-party libraries like Autofac or Ninject

• Used Razor engine to build dynamic views by creating Razor views with HTML and C# code to generate dynamic content

• Built single-page applications using Angular by creating components, services, and modules to manage data and UI

Implemented JWT and OAuth authentication in Angular and .NET Core apps.

• Used Angular's HttpInterceptor to add JWT token to requests

• Implemented OAuth2 authentication using IdentityServer4 in .NET Core

• Stored user credentials securely using ASP.NET Core Identity

• Used HTTPS to encrypt data in transit

• Implemented role-based authorization using ASP.NET Core Identity

Parallel stream is not always beneficial in Java Stream API.

• Parallel stream can be slower than sequential stream for small data sets or when the overhead of parallelism is greater than the benefit.

• Parallel stream can be beneficial for large data sets or when the operations are independent and can be executed in parallel.

• It is important to measure the performance of both sequential and parallel streams for a specific use case to determine which is more efficient.

Best practices for web app performance and security

• Use caching to improve performance

• Minimize HTTP requests and optimize images

• Implement input validation and sanitize user input to prevent attacks

• Use HTTPS and secure authentication methods

• Regularly update software and apply security patches

• Implement rate limiting and other security measures to prevent brute force attacks

Use Spring Boot's @Transactional annotation to handle multiple database transactions

• Use @Transactional annotation on service methods to handle transactions across multiple databases

• Configure multiple DataSource beans in your Spring Boot application

• Use @Qualifier annotation to specify which DataSource to use in each transaction

Millions of requests can be effectively managed through load balancing, caching, and scaling.

• Implementing load balancing to distribute requests evenly across multiple servers

• Utilizing caching mechanisms to store frequently accessed data and reduce response times

• Scaling infrastructure horizontally by adding more servers to handle increased traffic

• Using content delivery networks (CDNs) to cache and deliver content closer to users for faster access

Using Java streams API may impact performance depending on how it is implemented.

• Performance impact can vary based on the size of the data being processed.

• Improper use of streams can lead to unnecessary overhead and decreased performance.

• Parallel streams can improve performance for large datasets by utilizing multiple threads.

• Careful consideration of stream operations and data size is important for optimizing performance.

Logging in microservices follows 12 factor principles.

• Each microservice should log to stdout or stderr

• Logs should be treated as event streams and sent to a centralized log aggregator

• Logs should be structured data in a common format like JSON or syslog

• Logs should include contextual information like request ID, user ID, etc.

• Logs should be stored and rotated automatically

• Logs should be monitored for errors and anomalies

Spring Boot application startup involves auto-configuration, component scanning, and dependency injection.

• Spring Boot uses embedded Tomcat, Jetty, or Undertow server for running the application.

• Auto-configuration automatically configures the application based on dependencies and properties.

• Component scanning scans the project for components like controllers, services, and repositories.

• Dependency injection injects dependencies into components using annotations like @Autowired.

Authentication and Authorization in .Net core

• Authentication verifies the identity of a user while Authorization checks if the user has access to a resource

• .Net core provides built-in authentication and authorization middleware

• Authentication can be done using various methods like JWT, OAuth, Cookies, etc.

• Authorization can be done using policies, roles, claims, etc.

To configure 2 databases in Spring Boot, you can use multiple DataSource beans and specify them in application.properties.

• Define multiple DataSource beans in your configuration class

• Use @Primary annotation to specify the primary DataSource

• Use @Qualifier annotation to specify the secondary DataSource

• Configure the properties for each DataSource in application.properties

ConcurrentModificationException is a runtime exception thrown by Java when an object is modified concurrently while iterating over it.

• Occurs when a collection is modified while being iterated over using an iterator

• Can be avoided by using ConcurrentHashMap or CopyOnWriteArrayList

• Example: List list = new ArrayList<>(); Iterator iterator = list.iterator(); list.add("example");

Spring MVC is a web framework for building web applications, while Spring Boot is an opinionated way to create Spring applications.

• Spring MVC is a part of the larger Spring Framework, providing a model-view-controller architecture for web applications.

• Spring Boot is a standalone application that simplifies the Spring application development process by providing defaults for configuration.

• Spring Boot includes embedded servers like Tomcat, Jetty, or Undertow, making it easy to ...read more

Arrays store elements in contiguous memory locations, while linked lists store elements in nodes with pointers to the next node.

• Arrays have fixed size, while linked lists can dynamically grow or shrink.

• Accessing elements in arrays is faster (O(1)), while in linked lists it is slower (O(n)).

• Inserting or deleting elements in arrays can be inefficient, as it may require shifting elements, while in linked lists it can be done in constant time by adjusting pointers.

Microservice pattern is an architectural style where an application is composed of small, independent services that communicate with each other.

• Each service is responsible for a specific task or functionality

• Services communicate with each other through APIs

• Each service can be developed, deployed, and scaled independently

• Allows for greater flexibility, agility, and resilience

• Examples include Netflix, Amazon, and Uber

Microservices can increase complexity and require more resources to manage.

• Microservices can lead to increased network latency and communication overhead.

• Managing multiple services can be more complex than managing a monolithic application.

• Microservices require more resources to manage, including additional servers and monitoring tools.

• Testing and debugging can be more difficult in a distributed system.

• Security can be more challenging in a microservices architecture.

• Service d...read more

React Hooks are functions that let you use state and other React features without writing a class.

• React Hooks were introduced in React 16.8 to allow functional components to have state and lifecycle methods.

• They allow you to reuse stateful logic across multiple components without changing the component hierarchy.

• Some commonly used React Hooks are useState, useEffect, useContext, and useReducer.

• Example: useState hook allows you to add state to a functional component like a cla...read more

Virtual DOM is a lightweight copy of the actual DOM used for efficient updates in web development.

• Virtual DOM is a concept used in frameworks like React to improve performance by minimizing actual DOM updates.

• Changes are first made to the virtual DOM, then compared with the actual DOM to only update what has changed.

• This process helps reduce the number of manipulations needed on the real DOM, leading to faster rendering.

Functional components are simpler, stateless, and use hooks. Class components have lifecycle methods and state management.

• Functional components are simpler and easier to read/write.

• Class components have lifecycle methods like componentDidMount, componentDidUpdate, etc.

• Functional components use hooks for state management and side effects.

• Class components use this keyword for accessing props and state.

• Example: Functional component - const MyComponent = () => { return

  Hello Worl...read more

SOLID design principles are a set of five principles to help developers create more maintainable and scalable software.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Classes should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the program's correctness.

• I - Interface Segregation Prin...read more

Concurrent hashmap is used for thread-safe operations in a multi-threaded environment.

• Concurrent hashmap allows multiple threads to read and write to the map concurrently without causing data corruption.

• It is useful in scenarios where multiple threads need to access and update a shared hashmap.

• Example: Implementing a cache system where multiple threads can read and write data concurrently.

React js is a lightweight library for building user interfaces, while Angular is a full-fledged framework with more features and complexity.

• React is more flexible and allows for easier integration with other libraries and frameworks.

• Angular provides more out-of-the-box features like routing, forms handling, and dependency injection.

• React is easier to learn and has a larger community support.

• Angular has a steeper learning curve but offers more structure and consistency in larg...read more

Promises are objects representing the eventual completion or failure of an asynchronous operation.

• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and failure.

• They help avoid callback hell and make code more readable and maintainable.

Encryption on iOS involves using various APIs and libraries to secure data at rest and in transit.

• iOS provides built-in encryption APIs like CommonCrypto for data protection.

• Use Secure Enclave for storing sensitive data like passwords and keys.

• Implement TLS/SSL for secure communication over network.

• Consider using third-party libraries like CryptoSwift for additional encryption functionalities.