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.
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.
What is a common practice to reduce the load on a servlet?
- Caching
- Database Connection Pooling
- Lazy Loading
- Multithreading
Database Connection Pooling is a common practice to reduce the load on a servlet by efficiently managing and reusing database connections, improving performance.