🔸 TLDR
In the Java WebSocket API (JSR 356 / Jakarta WebSocket), you can attach message handlers only for TEXT, BINARY, and PONG. ✅
PING and ERROR are not message types you register a MessageHandler for. 🚫
🔸 TRY THIS QUIZ (BEFORE READING THE ANSWER) 🧠
Question (rephrased):
In a WebSocket session, for which incoming message types are you allowed to register a MessageHandler?
▪️ Error Message
▪️ Binary Message
▪️ Pong Message
▪️ Ping Message
(Select 2)
🔸 ANSWER ✅
Correct choices:
▪️ Binary Message
▪️ Pong Message
Simple explanation:
In this API, handlers are designed for the “payload” message types you receive from the client/server:
▪️ TEXT (not listed in the options above, but it’s valid)
▪️ BINARY ✅
▪️ PONG ✅
And there’s also an important rule:
👉 You can register at most one handler per message type per session (one for text, one for binary, one for pong). 🔒
🔸 WHY “PING” IS NOT IN THE LIST 🏓
PING is a control frame. In practice, you typically send pings (or let the container handle heartbeats) rather than registering a standard MessageHandler for “Ping messages”.
🔸 TAKEAWAYS 🎯
▪️ Register handlers for: TEXT, BINARY, PONG ✅
▪️ One handler per type, per session — no duplicates 🔐
▪️ Pings are usually for keep-alive / control, not app payload 🏓
#Java #WebSocket #JakartaEE #JavaEE #BackendDevelopment #Networking #APIs #SoftwareEngineering #Certification #TechSkills
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