In HTTP servlets, the _________ method is used to send error responses back to the client.
- doError()
- errorResponse()
- handleError()
- sendError()
The sendError() method in HTTP servlets is used to send error responses back to the client, providing information about the encountered error.
In a highly concurrent web application, how would you design a servlet to handle database connections securely and efficiently?
- Open a new database connection for each request.
- Store database connections as static variables.
- Use a connection pool to manage database connections.
- Use synchronized methods for database operations.
Using a connection pool is a best practice in highly concurrent applications as it efficiently manages and shares database connections, reducing the overhead of opening and closing connections for each request.
If a servlet manipulates a shared data structure, what must be done to ensure it operates correctly in a multithreaded environment?
- Avoid multithreading in servlets.
- Synchronize access to the shared data structure.
- Use multiple instances of the servlet.
- Use volatile keyword for the shared data structure.
Synchronizing access to the shared data structure is crucial in a multithreaded environment to prevent data corruption and ensure consistency. The synchronized keyword ensures that only one thread can access the shared data structure at a time.
To handle a POST request, the HttpServlet class uses the _________ method.
- doGet()
- doPost()
- handlePost()
- servicePost()
To handle a POST request, the HttpServlet class uses the doPost() method.
Describe a scenario where it's more efficient to use local variables instead of instance variables in a servlet.
- When the variable is used within a single servlet method.
- When the variable needs to be accessed from different sessions.
- When the variable needs to retain state across multiple requests.
- When the variable should be shared among different servlet instances.
Local variables are more efficient when the variable's scope is limited to a single method and doesn't need to retain state between requests. This reduces the memory footprint and avoids unnecessary storage of data that doesn't persist beyond the method execution.
An e-commerce website uses auto-scaling but faces downtime during sudden traffic spikes. What might be missing in their scaling strategy?
- Inadequate Database Scaling
- Inefficient Caching Strategy
- Insufficient Monitoring and Alerting
- Lack of Horizontal Scaling
Downtime during traffic spikes suggests a possible lack of horizontal scaling, where the application fails to dynamically add more instances to handle increased load. Monitoring and alerting can help detect such issues early.
What is the basic difference between horizontal scaling and vertical scaling?
- Distributing traffic
- Increasing resources on a server
- Increasing servers
- Load balancing
The basic difference is that horizontal scaling increases the number of servers to handle increased load, while vertical scaling involves increasing the resources (CPU, RAM) on a single server.
Which load balancing algorithm distributes requests based on the server with the least connections?
- Least Connections
- Random
- Round Robin
- Weighted Round Robin
The load balancing algorithm that distributes requests based on the server with the least connections is known as the Least Connections algorithm.
In the context of web applications, what does the term 'sticky session' mean?
- A session that retains client affinity
- A session with a fixed duration
- A session with persistent data
- A session with secure connections
'Sticky session' refers to a session that retains client affinity, meaning requests from the same client are directed to the same server, enhancing user experience in stateful applications.
What is a common challenge when scaling stateful applications?
- Caching
- Data consistency
- Load balancing
- Stateless communication
Achieving Data consistency is a common challenge when scaling stateful applications, as it involves ensuring that data is synchronized across multiple instances of the application.