Recoverable State Maintain permanent state. Requires traditional recovery. Roll-back only as far as checkpoint. TMs keep track of other TMs with which they communicate. IPC Synchronous, asynchronous or message.
Servers offer services by registering with name server.
Clients obtain service addresses to talk with servers. No lost or duplicated requests. If server terminates, bad error code is returned. Transactions Coordinator is site originating a transaction. Volatile and recoverable servers become participants in transactions.