Interview Questions and Answers: Real-Time Web Development with Blazor, SignalR, and WebSockets

1. What is Blazor, and how does it differ from traditional web development frameworks?

Answer: Blazor is a modern web framework from Microsoft that enables developers to create interactive web applications using C# and .NET instead of JavaScript. It has two hosting models:

• Blazor WebAssembly: Runs in the browser via WebAssembly.
• Blazor Server: Runs on the server, communicating with the browser in real-time using SignalR.

Unlike traditional JavaScript frameworks (e.g., React or Angular), Blazor leverages a single programming language (C#) for both client and server development, simplifying the process for developers with .NET expertise.

2. What are the key features of Blazor?

Answer:

• Component-Based Architecture: Reusable UI components.
• Full-Stack Development: Use C# for both front-end and back-end.
• Hosting Options: Supports Blazor WebAssembly and Blazor Server.
• JavaScript Interoperability: Call JavaScript when needed.
• Rich Tooling: Integration with Visual Studio.
• Built-In Security: Offers authentication and authorization features.

3. How do you deploy a Blazor application to Azure?

Answer:

1. Prepare the application for deployment in Release mode.
2. Choose the hosting option:
• Blazor WebAssembly: Deploy to Azure Static Web Apps or Azure Storage.
• Blazor Server: Deploy to Azure App Service.
3. Configure Azure resources for scalability and security.
4. Monitor the app using Azure Monitor or Application Insights.
5. Implement best practices such as HTTPS, caching, and auto-scaling.

4. What is SignalR, and how does it enable real-time communication?

Answer: SignalR is a library for adding real-time web functionality to applications. It establishes a persistent connection between the server and clients, enabling bidirectional communication. SignalR uses WebSockets when available and falls back to other technologies like Server-Sent Events (SSE) or Long Polling. It is often used for chat apps, live dashboards, and collaborative tools.

5. What are the differences between SignalR and Server-Sent Events (SSE)?

Answer:

Feature	SignalR	Server-Sent Events (SSE)
Communication	Bidirectional	Server-to-Client only
Transport	WebSockets, SSE, Long Polling	HTTP only
Scalability	Supports scaling with Redis, Azure	Limited scalability
Use Cases	Chats, games, real-time tools	Simple live updates (e.g., news)

6. Explain how WebSocket works and its use cases.

Answer: WebSocket provides full-duplex communication between a client and a server over a single, persistent connection. The process includes:

1. Handshake: Starts as an HTTP request and switches to WebSocket protocol.
2. Persistent Connection: Keeps the connection open for ongoing communication.
3. Bidirectional Messages: Enables both client and server to send messages independently.
4. Use Cases: Real-time apps like chat systems, stock price updates, collaborative tools, and gaming.

7. When should you choose Blazor over frameworks like React or Angular?

Answer:

• Use Blazor: When you're leveraging a .NET ecosystem, prefer using C# for full-stack development, or building enterprise apps tightly integrated with Azure.
• Use React: For dynamic, interactive UIs or apps that may extend to mobile (React Native).
• Use Angular: For large-scale apps requiring an all-in-one solution with strong TypeScript support.