I am in favour of allowing qos 0 to be stored, if desired, for disconnected clients - but that it not be required.

In other words, for a CleanSession=0 client:

• the client/server MUST store qos 1/2 messages, including those new messages due to active subscriptions on the server
• the client/server MAY discard QoS 0 messages

restructured proposal to fit narrative, previously read:

If a client connects using CleanSession=0:

• the client and server MUST store qos 1 and qos 2 messages, including those new messages due to active subscriptions on the server
• the client and server MAY discard existing and new QoS 0 messages

Take to TC call 19.09.2013

Changes made in WD-12

If set to 0, the Server resumes communications with the Client based on state from the current Session, otherwise it creates a new Session. The Client and Server will store the Session after the Client and Server are disconnected. After disconnection, the Server MUST accumulate further QoS 1 and QoS 2 messages that match any subscriptions that the client had at the time of disconnection. It MAY accumulate QOS 0 messages that meet the same criteria.

The Session state in the server consists of:
• The client subscriptions which it has acknowledged.
• All QoS 1 and QoS 2 messages for which transmission to the client is incomplete or where transmission to the client has not yet been started.
• The server MAY store QoS 0 messages for which transmission is incomplete or where transmission to the client has not yet been started.