Using CA OLQ Efficiently › Controlling Data Retrieval › OLQ DML User Exit

OLQ DML User Exit

OLQ will now invoke a user exit prior to issuing any native DML command. This facility enables users to examine, modify, or disallow navigational access to data from within OLQ. This might be used for security enforcement, statistics gathering, or checking for special data values.

To use this feature, the OLQSDMLE program must be relinked to include IDMSBALI and the user-written exit program. The user-written program must have an entry point of OLQDMLX.

The exit program is called in user mode. The registers on entry are as follows:

• R1 -- points to a parameter list that is the same as that generated for a native DML request. This is documented in the CA IDMS Programmer's Quick Reference Guide.
• R13 -- points to a 16-word save area in which the user exit should save the caller's registers.
• R14 -- contains the address to which control should be returned.
• R15 -- points to the OLQDMLX1 entry point within the user exit.

It is the user exit's responsibility to issue the DML command. If it decides that the command should not be executed, it must set the error status field in the IDMS communications block appropriately. The following is a sample program that can be used as a model for writing an OLQ DML exit.