Non-iSeries target restrictions and considerations for DDM

 

In addition to the restrictions that apply when the target server is an iSeries™ server, the restrictions in this topic also might apply when the target server is not an iSeries server or a System/38™.

Whether they apply depends on what the target server supports. You should refer to that server's documentation for more information.

• Only field data types that are common to the source and target servers can normally be processed by HLL applications. Floating-point data is an example of a data type that might not be common. Records can be transmitted that contain floating-point data, but the representation of floating-point data sent between servers might differ.

  The packed signs sent between systems might differ; for example, one server might use a C and another server might use an F.

  It is possible for you to write your application program so that it interprets the byte string for a record processed through a DDM file in any way that you want. However, whenever you do this, it is your responsibility to ensure that the data is handled correctly.

• Any operations that request a delay period before returning, such as for record lock wait times, might be rejected or changed to a zero wait time by the target server.

• Lock requests can be changed by the target server to a more restrictive lock. This might prevent some operations from occurring at the same time that can otherwise be performed on the local iSeries server. See ALCOBJ (Allocate Object) command for more information.

• Some iSeries parameters are ignored or cause errors if they are used during remote file processing on non-iSeries target servers. Examples are the FRCRATIO and FMTSLR parameters on some of the file commands. For more information, see OVRDBF (Override with Database File) command and see Copy commands with DDM.

• Member names are not supported in the DDM architecture. When the target server is not an iSeries server or a System/38, CL commands that have a MBR parameter, such as the Clear Physical File Member (CLRPFM) command, must be changed if the parameter specifies a member name that is different than the file name. If the member name is different, an error occurs if the command is used for a non-iSeries remote file. For some commands, MBR(*FIRST) or MBR(*LAST) is also valid. See Member-related commands with DDM for a list of all the CL commands related to file members, and for those that are not valid for accessing files on non-iSeries target servers.

  MBR(*LAST) is not supported by System/38.

• If a parameter on a CL command requires the name of a source file, then the names of the DDM files that refer to non-iSeries target files cannot be specified. An iSeries server cannot determine whether a remote file on a non-iSeries target is in fact a source file. (See Source file commands for a list of all the CL commands related to source files.)

• Certain iSeries commands that are valid for iSeries or System/38 target servers are not valid for other targets. See DDM-related CL command lists for the lists of commands that are not supported when the target is not an iSeries server or a System/38.

 

Parent topic:

Program modification requirements for DDM

 

Related reference

OVRDBF (Override with Database File) command
Copy commands with DDM
Member-related commands with DDM
Source file commands