SPI Programming Manual (G06.24+, H06.03+, J06.03+)

Introduction to SPI
SPI Programming Manual—427506-006
1-11
Implications for Management Applications
on a node running a C-series RVU in a network with a node running a D-series RVU.
The SCP and subsystem processes that communicate with an unconverted
management application should be run at low PINs. This approach provides the best
way, other than converting the application, to avoid the problems described here.
Obsolete Tokens in Responses
Even if a converted subsystem returns new tokens to convey data from a D-series
RVU, it continues to include the same information in previously used tokens from
C-series RVUs if the data fits in the old tokens. If the returned values do not exceed
the range supported by the old tokens, an unconverted requester sees no change.
(The requester can ignore the additional new tokens included in the response.)
However, if a converted subsystem cannot fit a value in a token from a C-series RVU,
it omits the token from the response and stores the value in a new token for the
D-series RVU. The subsystem does not return an error. The requester does not
discover the problem until it encounters the error ZSPI-ERR-MISTKN when it tries to
get the old token from the buffer.
For example, a subsystem that previously returned PIN values in an 8-bit token must
now include a larger token to accommodate PINs greater than 255. When the
subsystem deals with low-PIN processes, it can continue to use the 8-bit token in
addition to the new one. But if it has to return a high PIN, the 8-bit token is inadequate
and is not included in the response.
Obsolete Fields in Structured Tokens
Similar considerations apply to the fields of structured tokens. If data from a D-series
RVU fits in a field for a C-series RVU, the subsystem returns the field for the C-series
RVU in the structured token.
If the data does not fit in the field for the C-series RVU, and the field has a defined null
value, the null value is returned. If the token is an extensible structured token, the
value might be returned in a new field appended to the structure. Otherwise, the value
is returned in a new simple token.
If the data from a D-series RVU does not fit in the old field, and no null value is defined,
the entire structured token is omitted from the response. A new structured token with
expanded fields is returned in its place.
For information about how a specific subsystem adapts to the system running the D-
series RVU, see the management programming manual for the subsystem in question.
Caution. Subsystems do not return an error to indicate that a token from a C-series RVU has
been omitted from a response.