40+ SiValley Technologies Interview Questions and Answers

Spring Boot is a framework for building standalone, production-grade Spring-based applications.

• Annotations used in Spring Boot include @SpringBootApplication, @RestController, @Autowired, @Component, @Configuration, @EnableAutoConfiguration, and more.

• Validation in Spring Boot can be done using annotations such as @NotNull, @Size, @Min, @Max, and @Pattern.

• Spring Boot also provides built-in support for validation using the javax.validation API.

• Spring Boot's validation can be cu...read more

Questions on data structures, Java advantages, sorting algorithms, and string reversal using Java.

• Data structures: list, map

• Map works by storing key-value pairs and allows fast retrieval of values using keys

• Java advantages: platform independence, object-oriented programming, automatic memory management

• Sorting algorithms: bubble sort, quick sort, merge sort

• Reverse string using Java: use StringBuilder class and its reverse() method

State management libraries other than Redux

• MobX - simple and scalable state management

• Flux - unidirectional data flow architecture

• Vuex - state management for Vue.js

• Apollo Client - state management for GraphQL

• React Context API - built-in state management for React

• Recoil - experimental state management library for React

• XState - state management for finite state machines

Collections store data while streaming processes data in a sequential manner. Streaming API improves performance by reducing memory usage and increasing efficiency.

• Collections store data in memory while streaming processes data in a sequential manner without storing it.

• Streaming API allows for lazy evaluation, meaning data is processed only when needed, reducing memory usage.

• Streaming API can improve performance by enabling parallel processing of data, increasing efficiency.

• E...read more

Explaining immutability of String and other software engineering concepts

• String is immutable to ensure thread safety and prevent unintended modification

• Spring boot annotations simplify configuration and reduce boilerplate code

• Hashmap uses hashing to store and retrieve key-value pairs efficiently

• Arraylist and Linked list are both used to store collections of objects, but have different performance characteristics

• REST APIs use HTTP methods (GET, POST, PUT, DELETE) to interact w...read more

SCD type 2 is a slowly changing dimension technique in data warehousing to track historical changes in data.

• SCD type 2 maintains historical data by creating new records for changes instead of updating existing records

• It includes effective start and end dates to track when a change occurred

• In PowerCenter, SCD type 2 can be implemented using the Update Strategy transformation and maintaining historical data in a separate table

Log files can be recovered from deleted ones by using data recovery tools or techniques.

• Use data recovery tools like Recuva, PhotoRec, or Disk Drill to scan for and recover deleted log files.

• Check for backups of log files in case they were saved elsewhere before deletion.

• Look for temporary or cache files that may contain the information from the deleted log file.

• Avoid writing new data to the storage device where the log file was deleted to increase chances of successful recov...read more

Primary key uniquely identifies a record in a table, while a unique key ensures that all values in a column are distinct.

• Primary key is a combination of unique and not null constraints

• Primary key can only be one per table, while multiple unique keys can exist

• Primary key automatically creates a clustered index, while unique key creates a non-clustered index

• Example: Primary key for a 'users' table could be 'user_id', while a unique key could be 'email'

Class components are ES6 classes while functional components are functions.

• Class components have state and lifecycle methods while functional components don't.

• Functional components are simpler and easier to read and test.

• Functional components are preferred for simple UI components while class components are used for complex UI components.

• Example of class component: class MyComponent extends React.Component {}

• Example of functional component: function MyComponent(props) {}

We primarily use SQL databases for storing and retrieving data.

• SQL databases like MySQL, PostgreSQL, and Microsoft SQL Server are commonly used

• We also utilize NoSQL databases like MongoDB for certain projects

• Data may also be sourced from APIs, external services, or flat files

Worker process in ASP.NET is a separate process that runs in the background to handle incoming requests.

• Worker process is responsible for executing ASP.NET applications on the server.

• It runs independently of the main IIS process and can be configured to run multiple instances.

• Worker process manages application pools, handles requests, and processes code.

• Examples include w3wp.exe in IIS for handling ASP.NET requests.

Program to find balanced strings in Java

• Create a method that takes an array of strings as input

• Iterate through each string and check if it is balanced

• Use a stack to keep track of opening brackets and pop when closing bracket is encountered

• Return the list of balanced strings

Program to find unique objects in an array of strings using Java

• Create a HashSet to store unique objects

• Iterate through the array and add each object to the HashSet

• Convert the HashSet back to an array to get the unique objects

Singleton design pattern ensures a class has only one instance and provides a global point of access to it.

• Create a private static instance of the class within the class itself.

• Provide a public static method to access the instance.

• Ensure the constructor is private to prevent instantiation from outside the class.

• Use lazy initialization to create the instance only when needed.

componentDidMount is called after the component is mounted while componentWillMount is called before the component is mounted.

• componentDidMount is used for fetching data from APIs and updating the state

• componentWillMount is used for setting the initial state and making preparations for rendering

• componentDidMount is called once while componentWillMount is called multiple times

• componentDidMount is used for DOM manipulation

• componentWillMount is considered legacy and should be av...read more

Types of joins include inner join, outer join, left join, right join, and full join.

• Inner join: Returns rows when there is a match in both tables.

• Outer join: Returns all rows when there is a match in one of the tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full join: Returns rows when there is a match in one of the tables.

The project architecture follows a microservices-based approach with containerization using Docker and orchestration with Kubernetes.

• The project is divided into multiple microservices that communicate with each other through APIs.

• Each microservice is containerized using Docker to ensure consistency and portability.

• Kubernetes is used for orchestration to manage the deployment, scaling, and monitoring of the microservices.

• The architecture also includes a load balancer to distri...read more

setState is asynchronous

• setState schedules an update to a component's state

• The update may not happen immediately, but will be batched and executed later

• This can lead to unexpected behavior if not handled properly

Security tools for React applications

• Use ESLint and Prettier to enforce code quality and security standards

• Implement authentication and authorization using libraries like Passport.js and JSON Web Tokens

• Use security-focused libraries like Helmet to secure HTTP headers

• Implement input validation and sanitization using libraries like Joi and DOMPurify

• Use HTTPS to encrypt data in transit

• Implement rate limiting and other security measures to prevent attacks like CSRF and XSS

• Regular...read more

Data modelling involves designing the structure of a database to represent real-world entities and their relationships.

• Identify entities and their attributes

• Define relationships between entities

• Normalize data to reduce redundancy

• Choose appropriate data types and constraints

• Consider performance and scalability

Agile SDLC process with iterative development and continuous feedback loops.

• Agile methodology used for software development

• Iterative approach with regular sprints

• Continuous integration and deployment

• Frequent feedback from stakeholders

• Regular retrospectives to improve processes

Regression testing is the process of retesting modified software to ensure that previously working functionalities are still intact.

• Regression testing is performed after making changes to software to identify any new defects or issues introduced.

• It helps ensure that existing functionalities are not affected by the changes.

• It involves rerunning previously executed test cases to verify if the software still behaves as expected.

• Regression testing can be done manually or using au...read more

Constraints are limitations or restrictions placed on a system or process.

• Constraints define the boundaries within which a system must operate.

• They can include limitations on resources, time, budget, or functionality.

• Examples of constraints in software development include deadlines, hardware limitations, and security requirements.

MVC is a software design pattern that separates an application into three interconnected components: Model, View, and Controller.

• Model represents the data and business logic of the application

• View is responsible for rendering the user interface

• Controller handles user input and updates the model and view accordingly

• MVC promotes separation of concerns and modularity

• Examples of MVC frameworks include Ruby on Rails, Django, and ASP.NET MVC

Sanity testing is a subset of regression testing that quickly checks if the major functionalities of a software are working as expected.

• Sanity testing is a high-level testing approach

• It focuses on testing the core functionalities of a software

• It is performed after major changes or bug fixes

• It ensures that the software is stable enough for further testing

• It is a quick and shallow form of testing

• It helps in identifying critical defects early in the development cycle

State is mutable data owned by a component, while props are immutable data passed to a component.

• State can be changed by the component itself, while props cannot be changed by the component

• State is used to store data that can change over time, while props are used to pass data from parent to child components

• State is initialized in the constructor of a component, while props are passed down from the parent component

• Example: A counter component can use state to keep track of th...read more

Strict mode is a feature in React that helps with debugging and identifying potential issues.

• Enables additional checks and warnings during development

• Helps identify unsafe code and deprecated features

• Can be enabled globally or for specific components

• Example:

Yes, I am flexible with location and willing to relocate if required.

• I am open to working remotely or on-site

• I am willing to relocate for the right opportunity

• I have experience working with remote teams

A materialized view is a database object that contains the results of a query and is stored on disk for faster access.

• Materialized views store the results of a query physically on disk, unlike regular views which just store the query definition.

• They are used to improve query performance by pre-computing and storing the results of expensive queries.

• Materialized views need to be refreshed periodically to ensure that the data is up-to-date.

• They are commonly used in data warehous...read more

Constructor and destructor are special member functions in a class that are used to initialize and destroy objects, respectively.

• Constructor is called when an object is created, used to initialize the object's data members.

• Destructor is called when an object goes out of scope or is explicitly deleted, used to release resources.

• Example: class Car { public: Car() { cout << 'Constructor called'; } ~Car() { cout << 'Destructor called'; } };

• Constructors can be overloaded with diff...read more

Components in Angular are reusable building blocks that encapsulate HTML, CSS, and TypeScript code.

• Components are the basic building blocks of Angular applications.

• They are reusable and can be used to create complex UIs.

• Each component has its own HTML template, CSS styles, and TypeScript code.

• Components can communicate with each other using inputs and outputs.

• Examples of components include buttons, forms, and navigation menus.

Life cycle hooks are methods that get called at specific stages of a component's life cycle.

• They are used in Angular to perform actions at specific points in a component's life cycle

• Examples include ngOnInit, ngOnDestroy, and ngOnChanges

• They can be used to initialize data, perform cleanup, or update the component based on changes in input data

Axios is a promise-based HTTP client for making API requests in ReactJs.

• Axios is used to make HTTP requests from the client-side in ReactJs

• It supports all modern browsers and can be used with Node.js

• Axios can be used to make GET, POST, PUT, DELETE requests and more

• It can also handle request and response interceptors for global error handling and authentication

• Axios can be installed using npm or yarn

Designing a system for a 1L REST API involves creating a scalable and efficient architecture to handle large amounts of data and requests.

• Use microservices architecture to break down the system into smaller, independent services

• Implement caching mechanisms to improve performance and reduce load on the database

• Use load balancers to distribute incoming requests evenly across multiple servers

• Implement rate limiting to prevent abuse and ensure fair usage of the API

• Use a message q...read more

React is a JavaScript library for building user interfaces. Redux is a predictable state container for JavaScript apps.

• React is used for building reusable UI components

• Redux is used for managing the state of the application

• React and Redux are often used together in web development

• React uses a virtual DOM to efficiently update the UI

• Redux follows a unidirectional data flow pattern

Bulk load is faster for large amounts of data, while normal load is suitable for smaller amounts.

• Bulk load is more efficient for loading large amounts of data quickly.

• Normal load is better for smaller amounts of data to avoid overwhelming the system.

• Bulk load is commonly used for initial data migration or periodic batch updates.

• Normal load is used for real-time or incremental data updates.

• Examples: Bulk load - importing millions of records into a database. Normal load - updat...read more

Hooks are a feature in React that allow functional components to have state and lifecycle methods.

• Hooks were introduced in React 16.8

• useState is a hook that allows functional components to have state

• useEffect is a hook that allows functional components to have lifecycle methods

• Custom hooks can be created to reuse stateful logic across components

Fetch API is a built-in web API in modern browsers used to make HTTP requests from the browser to the server.

• Fetch API is used to make asynchronous HTTP requests from the browser to the server.

• It returns a Promise that resolves to the Response object representing the response to the request.

• It can be used with React to fetch data from an API and update the state of a component.

• Fetch API can be used with different HTTP methods like GET, POST, PUT, DELETE, etc.

• It can also be us...read more

Join and functions in SQL are used to combine data from multiple tables and perform operations on the data.

• Joins are used to combine rows from two or more tables based on a related column between them.

• Functions in SQL are used to perform operations on data, such as mathematical calculations or string manipulations.

• Examples of functions in SQL include SUM, AVG, CONCAT, and SUBSTRING.

Tech stack refers to the combination of programming languages, frameworks, libraries, databases, and tools used in a software development project.

• Programming languages: such as Java, Python, JavaScript

• Frameworks: like Spring Boot, Django, React

• Libraries: such as jQuery, Bootstrap

• Databases: like MySQL, MongoDB, PostgreSQL

• Tools: such as Git, Jenkins, Docker

A trigger is a special kind of stored procedure that automatically executes when an event occurs in the database management system.

• Triggers are used to maintain the integrity of the database by enforcing business rules or referential integrity.

• They can be set to execute before or after a data modification operation (INSERT, UPDATE, DELETE).

• Examples of triggers include auditing changes to a table, enforcing constraints, or updating related tables.

EME build activity refers to the process of creating a build for the EME (Encrypted Media Extensions) technology.

• EME build activity involves compiling the source code for EME implementation.

• It may include testing the build for compatibility with different browsers and devices.

• The build may also involve integrating DRM (Digital Rights Management) solutions for content protection.

• Examples of EME build activities include creating a build for a video streaming service that uses E...read more