The KOM Archive function is the function of process D2000 KOM that allows process to work in the offline mode (no connection to process D2000 Server) and to save values acquired from communication into a file (archive) for their later transmission into D2000 system.
Process D2000 KOM with the function KOM Archive may be started with parameters /KA <ArchivSize> and /KX. The parameter /KA enables the KOM Archive function and the parameter ArchivSize is the size of the archive file in megabytes (1 up to 400). The parameter /KX enables the operation of process D2000 KOM after a loss of the communication with D2000 Server. The parameter /KM defines the method for sending values from the KOM archive after connection with D2000 Server.
D2000 KOM with the function KOM Archive can be also run without
D2000 Server running. In that case, the configuration is
loaded from the file, that is placed in the subdirectory \KOMARC of the
application directory. The subdirectory is
created automatically after running process
D2000 KOM with the parameter
/KA. Besides the above mentioned parameters, there
is also the parameter /KC<ApplicationName>
required for the location of the configuration file.
Condition to run process D2000 KOM without process D2000 Server is the existence of the configuration file. The file is created and updated automatically after connecting process D2000 KOM to process D2000 Server. The file is updated after each change of objects that belong to given process D2000 KOM.
A particular solution (working while at least one process D2000 Server is in the system) is to run process D2000 KOM in the "shadow" mode (the parameters /RD<GroupName> and /W<MyName>,<MyNumber>)
KOM nr.1: kom /RDmy_group /Wself,1 /KCmy_application /KX /KA100 /TP
KOM nr.2: kom /RDmy_group /Wself,2 /KCmy_application /KX /KA100 /TP
D2000 KOM, started in this way, are connecting to the HOT server.
One of them is active and the others act as if it was connected to the STANDBY server. After the current
server drops out or it is switched, processes attempt to connect to the new HOT server. When all servers
drop out, processes
D2000 KOM stay in the status as they were before drop-out (one
is HOT and the other STANDBY).
A problem can occur, when the HOT process D2000 KOM drops out (the other process D2000 KOM is not notified and stays in the state STANDBY till it is connected to server).
Another problem is starting process D2000 KOM when no server exists - process D2000 KOM is automatically transferred into the HOT state as mentioned above.