Problems of unplanned dynamic backward error recovery for asynchronous
process systems are considered. A new recovery technique that allows
transparent dynamic structuring of processes based on the concept of d
ynamic conversations is proposed. The properties of these conversation
s are investigated, and a dynamic scheme of consistent recovery (rollb
ack) relying on them is proposed. To check resource expenditures durin
g recovery, four types of control over conversations are introduced. B
oth centralized and decentralized algorithms of the scheme's operation
are discussed. Problems of nested rollback of dynamic conversations a
re also examined.