NDB Open Exit Call Details

Using NCLEX01 for NDB Security › NDB Open Exit Call Details

NDB Open Exit Call Details

The following describes the parameter list passed on an &NDBOPEN call to NCLEX01:

The standard parameter list, as mapped by the $NMNCEX1 macro.
This parameter list contains information common to all calls to NCLEX01 for various reasons. It contains a function code, and information about the current user ID, and so on. The security correlator is passed to allow access to any security information provided by any security exits.
On an &NDBOPEN call, the NEXFUNC field has a value of 12 (decimal).
Field NEXNDEX1 contains a pointer to a supplementary parameter list containing additional information.
A supplementary parameter list, mapped by the NEXND DSECT. This DSECT is in the NCLEX01 macro.

Fields in this DSECT include:

NEXNDNAM	DS CL8	NDB name being opened
NEXNDFL1	DS X	Flag byte
NEXNDOPX	EQU X'80'	... EXCLUSIVE on &NDBOPEN
NEXNDOPI	EQU X'40'	... INPUT on &NDBOPEN
NEXNDOKM	DS 0XL2	Following 2 bytes. Note: initialized to 2X'FF'.
NEXNDOK1	DS X	... first OK operations flag.
NEXNDGTO	EQU X'80'	... 1 = &NDBGET ok.
NEXNDSCO	EQU X'40'	... 1 = &NDBSCAN ok.
NEXNDADO	EQU X'20'	... 1 = &NDBADD ok.
NEXNDUPO	EQU X'10'	... 1 = &NDBUPD ok.
NEXNDDLO	EQU X'08'	... 1 = &NDBDEL ok.
NEXNDDFO	EQU X'04'	... 1 = &NDBDEF ok.
NEXNDINO	EQU X'02'	... 1 = &NDBINFO ok.
NEXNDOK2	DS X	... 2nd ok operations flag.
NEXNDUDL	DS H	Length (0-50 decimal) of user data from &NDBOPEN statement.
NEXNDUDT	DS CL50	User data (padded/truncated to 50 chars) from &NDBOPEN statement (pad is blank).

These fields can be referenced to determine the action to take.

By returning R15 not equal to 0, all access to the NDB from the NCL process is denied. ASN NDB response code of 40 is returned, and this is handled based on the &NDBCTL ERROR= setting.

If R15 is returned with a 0, the 2-byte NEXNDOKM field is examined. If all of the defined bits are off (as listed previously), then the effect is the same as setting R15 not 0. Note that the NEXNDOKM field is initialized to all bits on before the call.

If any bits in the NEXNDOKM field are off, the associated &NDBxxxx verb cannot be used. Attempts to use it results in an NDB response code of 41. This too is handled as per the &NDBCTL ERROR= setting.

You can deny the use of the &NDBDEF verb with this exit. This forces the use of the NDB FIELD command to add, update, or delete field definitions from the database.

If the exit terminates abnormally while processing the &NDBOPEN request, the NCL process is terminated with an error.

The exit is attached as a subtask in all environments. It should be coded re-entrant because multiple copies may be executing simultaneously.

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