An input exit is used to decompress, flatten or otherwise manipulate each data record upon opening a file.
The table layout associated with the data file for which an input exit is to be run must include an exitname tag [EXIT] so Arbutus knows the calling application:
[EXIT] exitname
Where exitname is the name of the user supplied program that resides in a load library accessible to the application.
Input User Exits tags are automatically inserted in a table layout using the Data Definition Wizard when specifying a Flat File or VSAM server data source prior to defining it (for more information see Select Data Source).
Once specified, an input exit is initiated by simply opening the defined table from the Overview or via the command line using the OPEN command.
When an input user exit is used, the RECORD_LENGTH parameter within the table layout must specify the attributes of the record after manipulation has taken place. That is, the record length (or maximum record length for variable length records) must specify the maximum length that can result from the user exit. The VARIABLE parameter must be specified if the record after manipulation can be of variable length. As well, the field definitions must correspond to the field positions and data types after manipulation has taken place.