Interactive applications on the System i generally involve communication with:
Display files are objects of type *FILE with attribute of DSPF on the i5/OSsystem. You use display files to communicate interactively with users at display terminals. Like database files, display files can be either externally-described or program-described.
ICF files are objects of type *FILE with attribute of ICFF on the i5/OS system. You use ICF files to communicate with (send data to and receive data from) other application programs on remote systems (i5/OS or non-i5/OS). An ICF file contains the communication formats required for sending and receiving data between systems. You can write programs that use ICF files which allow you to communicate with (send data to and receive data from) other application programs on remote systems.
When a file in an RPG program is identified with the WORKSTN device name then that program can communicate interactively with a work-station user or use the Intersystem Communications Function (ICF) to communicate with other programs. This chapter describes how to use: