jetty.project/jetty-websocket/websocket-common/websocket-states.txt

Documenting the States of a WebSocket Session.

NEW: (Internal)

  A new WebSocket session.
  It has had no connection attempted yet.

CONNECTING: (RFC6455) // synonyms: HANDSHAKING

  The connection is being attempted, along with the Upgrade handshake.

CONNECTED: (Internal) // synonyms: HANDSHAKED, HANDSHAKEN, OPENING

  The connection is established.
  The User WebSocket Endpoint has not been notified yet.

OPEN: (RFC6455) // synonyms: OPENED

  User WebSocket Endpoint is now Opened (the onOpen method has been called, no close by onOpen)

CLOSING: (RFC6455)

  The close handshake has begun.
  Either the local initiated the close, waiting for the remote to reply.
  Or the remote initiated the close, and the local hasn't replied yet.
  This can be considered a logical half-closed state.

  + (sub state) CLOSE_FRAME_SENT (bool)

CLOSED: (RFC6455)

  The connection and session is closed.
  This means either the close handshake completed, or the connection was
  disconnected for other reasons.

----

Normal Client Initiated Close State Transition

  Client: State: NEW
  Client: WSEndpoint created
  Client: WSSession created
  Http GET w/Upgrade initiated
  Client: State: CONNECTING
  Upgrade Handshake negotiated (HTTP 101 response)
  Client: State: CONNECTED
  Client: WSEndpoint.onOpen() called
  Client: State: OPEN
  Client: WSEndpoint.onMessage() - received msg
  Client: WSSession.close(local close details)
  Client: State: CLOSING
  Client: Send CLOSE Frame to remote
  Remote: Received CLOSE Frame from client
  Remote: Sends CLOSE Frame reply (remote close details)
  Client: WSEndpoint.onClose(remote close details)
  Client: State: CLOSED
  Client: TCP Connection disconnect completely

----

Normal Remote Initiated Close State Transition

  Client: State: NEW
  Client: WSEndpoint created
  Client: WSSession created
  Http GET w/Upgrade initiated
  Client: State: CONNECTING
  Upgrade Handshake negotiated (HTTP 101 response)
  Client: State: CONNECTED
  Client: WSEndpoint.onOpen() called
  Client: State: OPEN
  Client: WSEndpoint.onMessage() - received msg
  Remote: Sends CLOSE Frame (remote close details)
  Client: Received CLOSE Frame from remote
  Client: State: CLOSING
  Client: WSEndpoint.onClose(remote close details)
  Client: after onClose()
          if can transition to CLOSED
            Client: Sends CLOSE Frame
  Client: TCP Connection disconnect completely

---

Overlapping Close State (Remote first) Transition

  Client: WSEndpoint created
  Client: WSSession created
  Http GET w/Upgrade initiated
  Client: State: CONNECTING
  Upgrade Handshake negotiated (HTTP 101 response)
  Client: State: CONNECTED
  Client: WSEndpoint.onOpen() called
  Client: State: OPEN
  Client: WSEndpoint.onMessage() - received msg
  Remote[t1]: Sends CLOSE Frame (remote close details)
  Client[t2]: WSSession.close(local close details)
  Client[t2]: State: CLOSING
  Client[t1]: Received CLOSE Frame from remote
  Client[t1]: Cannot transition to State: CLOSING (no-op)
  Client[t1]: WSEndpoint.onClose(remote close details)
  Client[t1]: after onClose()
          if can transition to CLOSED
            Client: Sends CLOSE Frame
  Client: TCP Connection disconnect completely