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.
What is the primary purpose of load balancing in web applications?
- Distribute incoming traffic
- Enhance security
- Execute database queries
- Store session data
The primary purpose of load balancing in web applications is to distribute incoming traffic across multiple servers, ensuring better performance and preventing overload on a single server.
How can an HTTP servlet differentiate between GET and POST requests?
- Checking the request type in the doGet and doPost methods.
- The HTTP servlet cannot differentiate between GET and POST requests.
- Using the HttpServletRequest method getMethod()
- Using the requestType attribute in the web.xml file.
An HTTP servlet can differentiate between GET and POST requests by using the HttpServletRequest method getMethod(), which returns the HTTP method of the request (e.g., "GET" or "POST"). This allows the servlet to determine the type of request being made.
Which strategy involves adding more servers to handle increased load in a web application?
- Horizontal scaling
- Load balancing
- Session management
- Vertical scaling
Horizontal scaling involves adding more servers to handle increased load in a web application by distributing the load across multiple machines.
To avoid thread safety issues, it's recommended to use __________ instead of instance variables in servlets.
- final variables
- global variables
- local variables
- static variables
Using static variables is recommended in servlets to avoid thread safety issues, as they are shared among all instances of the servlet and are stored in a shared memory space.
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.