Alternate Status
The prioritized list of servers that are specified in a configuration file contains sufficient information to determine what to do when communication between servers or between servers and clients fails. This could be due to failure of the communications medium or failure of the software on a machine (perish the thought) or failure of the computer hardware.
There may, however, be good reason to be able to inform RPC Manager of the health of a service. Typically, this will be where a service has to communicate to, or use, some third-party equipment. The service will need to indicate that it is, or is not, capable of performing the functions that it was designed for. A driver may typically use this facility to show its ability to communicate with a PLC.
This is achieved by setting or clearing the Alternate status of the service. RPC Manager monitors the Alternate setting to determine the most suitable service instance for the service. The rules by which server status is determined are described in the section on Server Evaluation Rules.
