RFC Ports

Use

The CSL tokens are moved if necessary when CSLEO_ENQUEUE is called. For this reason, the token managers in the linked systems have to communicate with each other by using an RFC. There are two database tables for setting up the communication channels between the systems:

CSL_CCP (CCP = Communication Channel Physical) to set up additional RFC ports for the CSL, besides the ones that are entered in the system
CSL_CCL: (CCL = Communication Channel Logic) to set up routing through other systems.

As far as the CSL is concerned, a physical communication partner is a direct communication partner that can be reached by a point-to-point connection. A logical communication partner, on the other hand, can also be reached by third-party systems.

Determining the RFC Port

For a Remote Function Call (RFC or tRFC) from a sender token manager S = {SY _S, NU _S} to a recipient token manager R = {SY _R, NU _R}, the CSL proceeds as follows:

The entries are delivered with the system.
The CSL first checks whether an RFC port for the logical system SY _R has been entered in the CSL_CCP database table. If so, the CSL uses this port.
If no RFC port for system SYR was entered in the CSL_CCP table, the CSL uses the RFC port that was entered in the TBLSYSDEST database table.
If there is no entry for SY _R, it is assumed that the name of the RFC port is the same as the name of the logical system ( BAPCLNT001, for example).

The entries in the CSL_CCP table therefore override the general RFC settings for any communication between the token manager and other systems. The table has the following fields:

Field Name	Meaning	Example
`CIRSY`	Logical system of the token manager where the communication starts (Communication Indicator System)	`RAMCLNT004`
`CIRNU`	Number of the token manager from `CIRSY`.	`01`
`CPPSY`	Physical communication partner of the token manager that is specified by `CIRSY` and `CIRNU` (Communication Partner Physical)	`ROMCLNT001`
`CPPNU`	Number of the token manager from `CPPSY`.	`01`
`PO`	RFC inbox (target port) of the token manager that is specified by `CPPSY` and `CPPNU`. This port must be entered in the `RFCDES` table in the outbound system. This table can be processed in transaction `SM59` only (see: Maintaining Remote Destinations).	`ROM_PORT`

Routing

Since an RFC connection between two systems is not always needed, we cannot assume that an RFC connection is set up between all linked systems. You can define a routing that is connected by an RFC to the other two systems by using a third-party system.

The routing is not described centrally. Instead, you specify for each token manager which is the nearest physical communication partner for reaching the logical communication partner. A row in the CSL_CCL database table contains such a reference:

Field Name	Meaning	Example
`CIRSY`	Logical system of the token manager where the communication starts (Communication Indicator System)	`FROCLNT000`
`CIRNU`	Number of the token manager from CIRSY.	`01`
`CPPSY`	Physical communication partner of the token manager that is specified by `CIRSY` and `CIRNU` (Communication Partner Physical). This is a token manager that the CSL can use to reach the logical communication partner.	`NXTCLNT002`
`CPPNU`	Number of the token manager from `CPPSY`.	`01`
`CPLSY`	Logical communication partner - the token manager that has to be reached at the end.	`FARCLNT001`
`CPLNU`	Number of the token manager from `CPPSY`.	`01`
`LEM`	Specifies the number of systems that can be used to reach the logical communication partner, minus 1. This is a typical routing parameter for selecting the shortest possible route.	`2`

Example

There is no RFC connection between systems ABC and XYZ. As shown below, you can use the entries in the CSL_CCL table to define a routing using systems DEF and GHI.

If the token manager in the ABCCLNT000 system wants to communicate with the token manager in the XYZCLNT000 system, the CSL looks in the table for the corresponding entry with the correct outbound system ( CIRSY field) and the correct logical target system ( CPLSY field). The CSL uses the nearest physical communication partner (entry in the CPPSY field) to track the route to the target system. In this case, the LEM field would have the value 3 in the ABC system, 2 in the DEF system, and 1 in the XYZ system.