A servlet receives a POST request with JSON data. What are the steps to correctly parse and use this data?
- Use the doGet() method and manually parse the JSON data using a JSON library.
- Use the doGet() method and rely on the servlet container to automatically parse the JSON data.
- Use the doPost() method and manually parse the JSON data using a JSON library.
- Use the doPost() method and rely on the servlet container to automatically parse the JSON data.
When handling a POST request with JSON data, it is appropriate to use the doPost() method, and manual parsing is often necessary using a JSON library. The servlet container does not automatically parse JSON data.
The _________ interface in Java EE allows the server to react to WebSocket lifecycle events.
- Decoder
- Encoder
- Endpoint
- Session
The Endpoint interface in Java EE allows the server to react to WebSocket lifecycle events.
To handle binary data in a WebSocket, the _________ method is typically implemented.
- onBinaryMessage
- onClose
- onError
- onTextMessage
To handle binary data in a WebSocket, the onBinaryMessage method is typically implemented.
WebSocket connections are maintained even if the underlying _________ changes, like from HTTP to HTTPS.
- URI
- protocol
- security
- transport
WebSocket connections are maintained even if the underlying URI changes, like from HTTP to HTTPS.
How can a servlet-based application detect and handle WebSocket upgrade requests?
- By inspecting the payload
- Using the Connection header
- Using the Upgrade header
- WebSockets cannot be used with servlets
A servlet-based application can detect and handle WebSocket upgrade requests by inspecting the Upgrade header in the HTTP request, indicating the intention to switch protocols to WebSocket.
How does the sendRedirect() method communicate the new URL to the client's browser?
- Via HTTP headers
- Via HTTP status code
- Via URL parameters
- Via server-side cookies
The sendRedirect() method communicates the new URL to the client's browser by sending an HTTP redirect response with the new URL in the HTTP headers.
What is the benefit of implementing the SingleThreadModel interface in servlets?
- Enhanced concurrent processing.
- Improved thread safety.
- Reduced memory consumption.
- Simplified servlet lifecycle.
Implementing the SingleThreadModel interface in servlets provides improved thread safety by ensuring that only one thread can execute the service method at a time, preventing concurrent access issues.
In a chat application using WebSockets, when a message is sent to a closed connection, what happens and how should it be handled?
- An error is thrown on the server-side.
- The WebSocket connection remains open for future messages.
- The client receives an error, and the server is notified.
- The message is silently discarded.
When a message is sent to a closed connection, the client should receive an error, and the server needs to be notified for proper handling and logging.
Consider a scenario where a servlet application needs to update client-side widgets in real-time. Which technology would be more efficient: AJAX polling or WebSockets?
- AJAX polling
- Both are equally efficient.
- It depends on the specific use case requirements.
- WebSockets
WebSockets would be more efficient in real-time updates as they allow for bidirectional communication and eliminate the need for continuous polling, reducing latency and server load.
What happens if the init() method of a Servlet throws an exception?
- Servlet becomes inactive
- Servlet continues to initialize
- Servlet fails to initialize
- Servlet restarts
If the init() method of a Servlet throws an exception, the servlet fails to initialize, and the servlet container may mark the servlet as unavailable.