Distributed Name Service (DNS) Management Programming Manual

Event-Message Descriptions
Event Messages
6–60 46958 Tandem Computers Incorporated
What Happens
In the following explanation of event message 35, the following terms are used:
INITIALIZATION TIMESTAMP. This is a Julian timestamp denoting the time
when DNS was last initialized on a system. The initialization timestamp is stored
in the DNS-QUEUE-FILE by DNSCOM during DNS initialization.
VERSION RECORD. This is a record in the DNS-QUEUE-FILE, containing the
initialization timestamp of another system in the network.
EXPORTING SYSTEM. This is the system where the name exporter is running.
IMPORTING SYSTEM. This is the system where the name manager is running.
When a name exporter opens a remote name manager, it sends a MYVERSION
request to the manager containing the exporting system’s initialization timestamp.
The name manager looks in its queue file for the exporting system’s version record,
and does the following:
1. If the record does not exist, the name manager assumes that this is the first time it
has heard from the exporting system. The name manager replies that the
exporting system should re-export any name definitions that may have been
replicated on the importing system.
The name exporter exports the definitions of such names and then sends a
STOREVERSION request, which again contains the exporting system’s
initialization timestamp. The importing system creates a version record for the
exporting system and generates a ZDNS-EVT-INITIAL-IMPORT event message
with a reference to the exporting system.
Finally, the name manager inserts an ATTENTION record into the
DNS-QUEUE-FILE on its system; this record instructs the name exporter on the
importing system to open the name manager on the exporting system and perform
this same sequence of interactions with the roles of the two systems reversed.
2. If the record exists and the timestamp in the record matches the timestamp in the
MYVERSION request, the name manager replies that no re-export is required.
3. If the record exists but the timestamp in the record does not match the timestamp
in the MYVERSION request, the name manager deletes all names defined on the
exporting system, as well as the exporting system’s version record. Once this is
done, the scenario is the same as in (1), above.