iSeries server and System/38 DDM differences

This topic consists of a list of differences between the iSeries™ server and System/38™.

Three parameters are added to the Create DDM File (CRTDDMF) and Change DDM File (CHGDDMF) commands. These parameters are the remote location name (RMTLOCNAME), local location name (LCLLOCNAME), and the remote network ID (RMTNETID). DDM files can be created either in the System/38 environment or on the iSeries server.
The Submit Remote Command (SBMRMTCMD) command must be in the syntax of the target server, even in the System/38 environment. For example, when a System/38 submits commands to an iSeries server, the syntax of the iSeries server must be used.
The remote file name must be in the syntax of the target server.
The default value for the DDMACC parameter on the Change Network Attributes (CHGNETA) command on the System/38 is *REJECT. The default value for the DDMACC parameter on the iSeries server is *OBJAUT.
On the System/38, files are created as FIFO (first in, first out) or LIFO (last in, first out). The default for creating a file is FIFO on the System/38.
When running System/38 applications that are dependent on duplicate keys being FIFO or LIFO to an iSeries server, you should specify either FIFO or LIFO when creating your iSeries files because there is no default for iSeries files. This means the iSeries server looks for an available index path to share, which can be either FIFO or LIFO.
Keyed files containing fields other than character (zoned or packed) created by using DDM on a remote System/38 might result in the fields defined as character fields. This might produce unexpected results when such a file is processed using relative keyed operations. Because the file is created with fields that are not packed, records might be returned in a different order than expected or no record can be found when one is expected.
As an example, the ILE RPG SETLL statement might fail unexpectedly with record not found or might select a record other than the record expected when using packed fields to a System/38 file. Only character and unsigned numeric fields should be used as key fields for files that are created by using DDM on the remote System/38.
To support adding a record by the relative record number operation, an ILE RPG program is required for DDM to do a READ CHAIN(RRN) operation followed by a WRITE operation. The file must be opened for read and update authorities, and the user must have read and update data authorities to the file.
Format selector programs on adding a record by the relative record number operation are only supported on the iSeries server. Incompatibilities might arise for those users who have a format selector program for a logical file if they do direct file processing.