In Java EE, the _________ method is used to send a message to the connected WebSocket client.
- broadcastMessage()
- sendMessage()
- sendText()
- writeMessage()
In Java EE, the sendMessage() method is used to send a message to the connected WebSocket client.
The annotation _________ is used to configure the endpoint of a WebSocket server.
- @EndpointConfig
- @ServerEndpoint
- @WebSocketConfig
- @WebSocketEndpoint
The annotation @ServerEndpoint is used to configure the endpoint of a WebSocket server.
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.
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.