Which of the following is a common practice for ensuring thread safety in servlets?
- Avoiding the use of static variables
- Releasing all resources in the destroy() method
- Synchronization of the service() method
- Using a single shared resource in the servlet
A common practice for ensuring thread safety in servlets is avoiding the use of static variables, as they can lead to conflicts when multiple threads are accessing the servlet concurrently.
How can a server control the lifetime of a cookie in a client's browser?
- Setting the Domain attribute
- Setting the Expires attribute
- Setting the Max-Age attribute
- Setting the Path attribute
The server can control the lifetime of a cookie by setting the Max-Age attribute, specifying the maximum age of the cookie in seconds.
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.
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.
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.
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.
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.
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.
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.
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.
A thread-safe servlet ensures that shared data is accessed in a _________ manner.
- parallel
- random
- sequential
- synchronized
A thread-safe servlet ensures that shared data is accessed in a synchronized manner. This prevents multiple threads from accessing the shared data simultaneously, reducing the risk of data corruption and ensuring proper thread safety.
The _________ method should be used carefully in servlets due to potential thread safety issues.
- destroy()
- doGet()
- init()
- service()
The service() method should be used carefully in servlets due to potential thread safety issues. It handles requests and might result in multiple threads accessing the servlet concurrently, requiring careful consideration for thread safety.