DISCONNECT Disconnect notification

The DISCONNECT message is sent from the client to the broker to indicate that it is about to close its TCP/IP connection. This allows for a clean disconnection, rather than just dropping the line.

Sending the DISCONNECT message does not affect existing subscriptions. They are persistent until they either explicitly unsubscribed, or if there is a clean start. The broker retains QoS 1 and QoS 1 messages for topics to which the client is unsubscribed until the client reconnects. QoS 0 messages are not retained, since they are delivered on a best efforts basis.

Fixed header

The fixed header format is shown in the table below.

bit 7 6 5 4 3 2 1 0
byte 1 Message Type (14) DUP flag QoS level RETAIN
  1 1 1 0 x x x x
byte 2 Remaining Length (0)
  0 0 0 0 0 0 0 0

The DUP, QoS, and RETAIN flags are not used in the DISCONNECT message.

Payload

There is no payload.

Variable header

There is no variable header.

Related concepts
WebSphere MQ Telemetry Transport

Related reference
WebSphere MQ Telemetry Transport Quality of Service levels and flows
WebSphere MQ Telemetry Transport fixed header