Q.19: Describe the RESTful API design principles.
Answer:
RESTful APIs follow six guiding principles to ensure predictable, scalable, and well-structured services.
- Uniform Interface: Resources are named consistently using HTTP methods (GET, POST, PUT, DELETE), which standardizes interactions.
- Client-Server Architecture: It separates concerns by allowing clients to make requests and servers to process them independently.
- Statelessness: Each request must contain all the necessary information; servers don’t retain information about previous requests.
- Cacheability: Resources can be cached for better performance and faster response times.
- Layered System: Multiple layers of intermediaries can be added between clients and servers to improve scalability and load balancing without impacting communication.
- Code on Demand (Optional): Servers can send executable code to the client to enhance functionality.
By following these principles, RESTful APIs provide efficiency, scalability, and ease of integration for modern web services.
Q.20: What are the SOLID principles in object-oriented design?
Answer:
SOLID is an acronym for five design principles that help in building maintainable, flexible, and scalable software:
- Single Responsibility Principle (SRP): Each class should have one responsibility, ensuring clear and manageable code.
- Open/Closed Principle (OCP): Software entities should be open to extension but closed to modification, making it easier to add new functionality without altering existing code.
- Liskov Substitution Principle (LSP): Objects of a superclass should be replaceable with objects of a subclass without affecting correctness, ensuring consistency in inheritance.
- Interface Segregation Principle (ISP): Clients should not be forced to implement interfaces they don’t use, promoting clean and focused interfaces.
- Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules; both should depend on abstractions, reducing tight coupling.
These principles improve software’s robustness, making it easier to manage and extend.
Q.21: What are the advantages and disadvantages of microservices architecture?
Answer:
Microservices architecture structures an application as a collection of small, loosely coupled services. Here are the advantages and disadvantages:
- Advantages:
- Agility: Independent services lead to faster development cycles.
- Scalability: Each service can scale independently based on its demand.
- Resilience: Failure of one service doesn’t bring down the entire system.
- Technology Flexibility: Each service can use the best technology suited for its purpose.
- Agility: Independent services lead to faster development cycles.
- Disadvantages:
- Complexity: Increased management overhead in terms of communication, infrastructure, and monitoring.
- Testing Challenges: Testing a distributed system is often complex and time-consuming.
- Debugging Difficulty: Identifying issues across services can be challenging.
- Higher Costs: Initial setup and maintenance are typically more expensive than monolithic systems.
- Complexity: Increased management overhead in terms of communication, infrastructure, and monitoring.
Microservices are best for applications that require flexibility, scalability, and independent development teams.
Q.22: What is the difference between horizontal and vertical scaling?
Answer:
Scaling methods vary depending on your application’s needs:
- Horizontal Scaling: This involves adding more machines (nodes) to distribute the load across multiple systems. It is highly flexible and resilient, suitable for high traffic or heavy workloads.
- Vertical Scaling: This involves upgrading the resources (CPU, RAM, storage) of an existing machine to handle more tasks. It is easier to implement but may lead to a single point of failure and can be more expensive at scale.
- When to Use:
- Horizontal Scaling: Best for high-traffic, distributed applications.
- Vertical Scaling: Suitable for simpler applications with low traffic.
- Horizontal Scaling: Best for high-traffic, distributed applications.
Q.23: What is the difference between HTTP methods GET and POST?
Answer:
GET and POST are two common HTTP methods with distinct purposes:
- GET: Used to retrieve data from a resource. It appends parameters to the URL and is idempotent, meaning repeated requests produce the same result. GET requests are cached and bookmarked easily.
- POST: Used to send data to a resource, typically in the request body. It is non-idempotent, meaning repeated requests may have different outcomes. POST requests are not cached and are more secure than GET.
The choice between GET and POST depends on whether you are retrieving data (GET) or submitting data (POST).
Q.24: How can you maintain API security?
Answer:
Securing APIs is essential to prevent unauthorized access and data breaches. Here are the best practices for maintaining API security:
- Token-based Authentication: Use tokens (e.g., OAuth) to securely authenticate users and prevent unauthorized access.
- Encryption and Signatures: Secure API communications with encryption protocols like TLS, and use digital signatures to verify the integrity of requests.
- Regular Vulnerability Assessments: Stay proactive by patching known vulnerabilities and monitoring the API for potential threats.
- Quotas and Throttling: Implement rate limiting to avoid abuse and protect against Denial-of-Service (DoS) attacks.
- API Gateway: Use an API gateway to centralize authentication, monitoring, and control.
These practices ensure that your API remains secure, protecting user data and preventing malicious activities.
Q.25: What happens when you search for something on www.google.com?
Answer:
When you perform a Google search, several backend processes occur:
- Query Submission: Your search term is sent as a GET request to Google’s servers.
- Processing and Parsing: Google’s web crawlers analyze and index billions of web pages to find relevant results.
- Ranking and Retrieval: The query is matched against the indexed pages using algorithms like PageRank and BM25, ranking them based on relevance and authority.
- Serving the Results: The top results are retrieved and formatted into HTML snippets, which are sent to your browser.
- Displaying the Results: Your browser receives the results and presents them in an easily readable format.
Additional processes like load balancing, caching, and personalized search ensure a fast and relevant experience.
