The administrator of the UTM application initiates the exchange of the application program with the command KDCAPPL PROG=..., for example. The program exchange then runs separately.
If you specify KDCAPPL PROG=NEW, the application program of the generation PROG(+1) is loaded; specifying KDCAPPL PROG=OLD loads the application program of the generation PROG(-1).
For this reason, it is advisable to define the last generation of the FGG as the base. This generation is then loaded when the application starts. A new generation of the application program is transferred to the FGG with the relative generation number PROG(+1) (default setting for KDCPROG TRANSFER). When a program is exchanged with KDCAPPL PROG=NEW, the new generation of the application program is loaded. openUTM automatically switches the base to the generation currently loaded, i.e. the last generation. If you then want to switch back to the application program previously loaded, specify KDCAPPL PROG=OLD.
The exchange is implemented for each work process of the application. For each individual work process, the active application program is terminated and the new application program loaded after the current job has been executed. The exchange is not implemented for the next work process until the exchange for this work process has concluded. This means that the application run is not significantly interrupted by the application exchange. In this way, the user is unaware of the application exchange and can continue to work unhindered.
While the application is being exchanged, the process described may result in the situation that jobs are simultaneously processed by individual work processes with the old application program and by other work processes with the new application program. You can prevent this if you issue the administration command KDCAPPL TASKS=1 to reduce the maximum permitted number of work processes to 1 before the exchange takes place (e.g. with the administration command KDCAPPL TASKS=1).
After the application exchange has ended, a UTM message is output to inform the UTM administrator as to whether the exchange was successful or was aborted with errors. The administrator cannot start the next application exchange until this exchange is concluded for all work processes.