Figure: Parameters of RO-INVOKE
Figure 
shows the parameters used with RO-INVOKE. The operation value is a
number, either an integer or an object identifier, that uniquely
identifies the operation to be performed. An optional argument allows
the invoking entity to transmit an argument to be used in carrying out
the operation. The invocation identifier is a serial number
required because it is
possible to have multiple invocations of the same operation executing
concurrently. When that happens and an operation completes, some means
of identifying its result with the correct invocation request is needed.
Since some operation invocations may invoke other operations, there may
be parent and child processes associated with an invocation. In that
case a linked invocation identifier is used to associate this invocation
of an operation with its parent. Priority, if given, helps the
ROSE service provider to balance the attention that should be given to
individual remote operation invocations. Since both application
entities may be issuing multiple RO-INVOKE operations, some may have to
wait for service while others are served. The priority parameter (an
integer with low numbers designating high priority) helps ROSE allocate
service appropriately.
RO-RESULT is an unconfirmed service that reports successful
operation to the ROSE initiator. Its parameters are shown in
Figure . The invocation identifier matches
this result to the correct invocation. A result is returned if
one is generated by the invocation. If a result is generated, the
operation number (operation value) of the invocation is provided
for type-checking purposes, and is used only in those cases where the
operation produces a result. Priority corresponds to
the priority parameter of the invocation. It is used to determine where
the right to send data should be, if data sending is controlled by a
token.
Figure: Parameters of RO-RESULT
RO-ERROR is a service used by the responder to an RO-INVOKE to report
a failure to execute the requested operation. Its parameters appear in
Figure . The invocation identifier matches
the corresponding value in the RO-INVOKE service and matches the failed
operation to the correct invocation. The error value is a numeric
representation of the particular failure that occurred. If appropriate,
a parameter carries further information about the error. Priority is used as in RO-INVOKE and RO-RESULT to assist the ROSE
service provider in ordering its service when multiple invocations are
active.
Figure: Parameters of RO-ERROR
Rejection occurs when a problem is detected in an invocation, a
result, or an error report, and comes from either the ROSE service user
(RO-REJECT-U) or from the ROSE service provider (RO-REJECT-P).
RO-REJECT-U is an unconfirmed service whose parameters are shown in
Figure . The invocation identifier and
priority parameters have the same meaning as in RO-INVOKE and
RO-RESULT and RO-ERROR. Reason identifies the cause of the
rejection as one of those listed in Figure .
RO-REJECT-U is issued by either the responder
to the remote operation, if the problem is in the invocation, or the
initiator, if the problem is in the result or error notification.
Figure: Parameters of RO-REJECT-U
RO-REJECT-P is a rejection issued by ROSE - the service provider -
not the ROSE service user. Its parameters are shown in
Figure . Surprisingly, perhaps, the invocation identifier not a mandatory parameter. The invocation
identifier will appear if it is known. Since a rejection by the ROSE
service provider usually indicates a protocol error, the invocation
identifier might not be available. Returned parameters are passed
to the ROSE service user in RO-REJECT-P.indication if the invocation,
result, or error that originally contained the parameters was not
delivered to its peer application entity.
Figure: Parameters of RO-REJECT-P