On receiving a MEMBER_LIST, the new user learns the room's membership and sequence numbers. To finish joining, the new user sends a JOIN, including a CONFIRM for each existing member. Each member will respond to her JOIN message with a CONFIRM, containing a new sender key.
Until the new user has finished joining, existing members continue exchanging DATA with their old sender keys. Once the last confirmation has been received, existing users switch to their new sender keykeys.
Once the present new user has received all CONFIRM messages from the existing membership, she is successfully joined. If other users sent a QUERY in the meantime, the next one will be responded to with a MEMBER_LIST.
== Nonblocking Join ==