OpenTP1 Version 7 Programming Guide
A client UAP can use a combination of the following three types of RPC on a single OpenTP1 system by using the multi-scheduler facility to request a service provided by a queue-receiving server (SPP that uses the schedule queue) on a remote node.
The figure below shows an outline of an RPC that uses the multi-scheduler facility.
Figure 2-15 Outline of an RPC with the multi-scheduler facility
A service request that uses the multi-scheduler facility is scheduled only to nodes on which the multi-scheduler daemon is active. However, if there is no available OpenTP1 system on which the specified multi-scheduler daemon is active at the time the service request is issued, the service request is sent to the master scheduler daemon.
Specifying the port number of a multi-scheduler daemon when issuing a service request with a specified port number causes the RPC to schedule the service request via the specified multi-scheduler daemon.
If a service request's destination user server is blocked or terminated at the time the multi-scheduler daemon receives the service request, the service request is sent to a multi-scheduler daemon on another node that uses the multi-scheduler facility. If the specified multi-scheduler daemon does not exist on any other node, the service request is sent to the master scheduler daemon.
If a multi-scheduler daemon terminates abnormally while the system is online, the client UAP allocates an appropriate port number to the multi-scheduler daemon that terminated abnormally and restarts it. The OpenTP1 system does not go down in this case. However, if restart fails twice, the OpenTP1 system goes down.
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