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This section defines basic fault tolerance mechanisms that must be implemented for Fault Tolerant CORBA. The client-side mechanisms
are intended to be simple light weight extensions to CORBA that will be easy to implement. These mechanisms enable client-side
ORBs to achieve a higher level of reliability by exploiting the fault tolerance mechanisms defined for server-side ORBs.
In particular, this section defines:
• Interoperable object group reference that contains multiple TAG_INTERNET_IOP profiles, each of which contains the TAG_FT_GROUP component and one of which may contain a TAG_FT_PRIMARY component. The interoperable object group reference may contain the TAG_MULTIPLE_COMPONENTS profile, which may contain the TAG_FT_GROUP component.
• Failover semantics for Fault Tolerant CORBA that extend the failover semantics for the CORBA core.
• Most recent object group reference for a server object group, using the FT_GROUP_VERSION service context in a client’s request message. The FT_GROUP_VERSION service context allows the server to determine whether the client is using the most recent object group reference for the server object group.
• Transparent reinvocations of requests, using the FT_REQUEST service context in a client’s request messages, the client-side Request Duration Policy and the fault handling semantics of GIOP messages. The FT_REQUEST service context prevents a request from being executed two or more times as a consequence of reinvocation of the request on a backup server after a fault.
• Heartbeating of the server, using the TAG_FT_HEARTBEAT_ENABLED component of the TAG_INTERNET_IOP profile, the client-side Heartbeat Policy and the server-side Heartbeat Enabled Policy. This allows the client to detect failure of the server.