Software Reference Manual - NetEx

Appendix A: User Modules
BFX provides the capability to perform some record-type conversion and provisions for transfer to non-IBM
systems. For applications where custom coding is required, BFX allows for the incorporation of user-written
modules to read and write file data and to process jobs before delivery to the remote host. The user may write
record or block modules to perform this function.
Users may want to write block modules under the following conditions.
Character sets or assembly/disassembly modes are used which are not provided by BFX.
Users want to supply logical blocks.
User-written record modules should satisfy most other special needs not provided by BFX.
It should be noted that the NESi block modules are highly specialized in that they call record modules. Most
user-written block modules would not necessarily call record modules.
The rest of this section describes the NESi block and record modules. Appendix A, “BFX Internal Summary”
on page 91 provides BFX internal information which may be helpful when writing block modules. The following
paragraphs describe writing record, block, and job submission modules.
Writing Record Modules
Record modules are called by NESi block modules and are designed to be entered from a single entry point.
(User-written block modules would probably not call record modules.) The first time the record module is
called, it is expected to open a file for output or input. On subsequent calls, the record module will need to
either provide or accept a logical record each time it is called. Record modules can also insert messages to be
sent to the other side of the BFX transfer process.
It should be noted that the conventions used here are those enforced by the standard NESi bock modules. If
the user writes their own block modules, the user block modules may or may not call record modules, or may
call a record module using completely different conventions.
Record modules are normally written to be either sending or receiving record modules. The argument list
passed to both types of modules is identical and is described below. The use of these parameters differs between
module types and is discussed in the parameter description.
The following paragraphs describe the FORTRAN entry to the record module, Assembler entry to a record
module, a block and record module entry and exit summary, and examples of a sending and receiving record
module.
MAN-REF-H211-05 Appendix A: User Modules Page 59