CHAIBP@NUSDISCS.BITNET (11/29/89)
Alistair Munro, Thanks for your reply. I couldn't reach you via gateway mail so I send to this mailing list. Is the following address correct ? MunroAT%np1a.bristol.ac.uk@NFSnet-Relay.AC.UK Anyway, I have the following queries related to CCR : 1. Since CCR is not included in ISODE, how can Service Elements in the application layer - eg. FTAM, provide reliable application- oriented information transfer over an arbitrary network ? Using a reliable class-4 Transport doesn't help. Take for instance, in the midst of a file transfer there is an application failure - the application programs hang due to memory corruption. But the the communication subsystem - TP-4, which is residing on a special networking card is not affected. In this case, since the failure occurs above transport layer, it is of course not transport layer's responsibility to recovery. The application has to be capable of recovering itself. But without CCR, how can be this be done ? 2. CCR services are made possible only with the use of secure data. If secure data is lost, CCR services will breakdown. What machanisms can be used to ensure that secure data is never lost with whatever possible kinds of failure - disk crash, power failure, system breakdown, etc. In mainframe/mini systems, this is most commonly done using mirror disks, but there seems to be no equaly good solutions in workstations or microcomputers. What's your solution ? 3. With the C_BEGIN parameter list, there is the "branch identifier" which is used to uniquely identify a branch with an atomic action tree. It is mentioned in the spec. that this parameter should be carried by CASE Kernel. What's "CASE Kernel" ? CASE is defined to composed of ASCE, ROSE and CCR. Does CASE Kernel refers to any of these ? If not, what then ? Any info would be greatly appreciated. B. P. Chai