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.
Describe the lifecycle of a WebSocket in a Java web application.
- Connect, Communicate, Disconnect
- Create, Transmit, Terminate
- Handshake, Data Transfer, Termination
- Initialization, Open, Close
The lifecycle of a WebSocket in a Java web application involves a handshake phase, followed by data transfer, and finally, termination. This sequence includes establishing the connection, exchanging data, and closing the connection.
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.
A high-frequency trading application needs to send and receive financial data with minimal latency. What WebSocket features make it suitable for this application?
- Caching and client-side data storage
- Long polling and server-sent events
- Multiplexing and low latency
- Request-response pattern and reliable message delivery
WebSockets, with features like multiplexing and low latency, are suitable for high-frequency trading applications, as they enable efficient, bidirectional communication with minimal delay in data transmission.