From R/2 to R/3 

Purpose

An ABAP program in an R/2 System starts an ABAP program in an R/3 System and exchanges data with this program.

You can start the target program from the R/2 host via an SAP communications program.

Prerequisites

The SAP communications program and the SAP Gateway must be on a UNIX computer known in the SNA network. The target program, on the other hand, can be on a UNIX computer not in the SNA network.

Side info files must be configured on the UNIX computer known in the SNA network and on the Gateway host.

With this constellation, you must note the following guidelines:

The destination of the function call must match the corresponding entry in XCOM and RFCD.

For more details on the RFC interface, refer to the documentation Remote Communications.

IBM:

The program runs under the user ID specified in the SNA definition, in the home directory of this user ID.

HP:

The program runs under the user ID sna (ID, under which the SNA kernel runs), in the directory containing the program.

IMS:

If you log on to an IMS security system, the session must not be closed. For this reason, the environment variable SAP_KEEP_SESSION was introduced.

For SAP_KEEP_SESSION=1, the session is retained despite the statement COMMUNICATION DEALLOCATE.

Process flow

  1. The calling ABAP program reads the TP name in the XCOM table and starts the SAP communications program gwhost (for CICS) or gwims (for IMS) under this name on a computer known in the SNA network.
  2. The communications program sets up a Conversation with the SAP Gateway.
  3. The SAP Gateway starts the actual target program. The computer, on which it is located, does not have to be known in the SNA network.

The communications program simply passes on the data during the CPI-C dialog.

For details on the configuration of side info files, refer to the following topic in the documentation BC SAP Communication: Configuration: