qRFC With Send Queue (SAP Library - RFC Programming in ABAP)

qRFC With Send Queue

To guarantee an LUW sequence dictated by the application, the tRFC is serialized using queues. It is therefore called queued RFC (qRFC). Due to the serialization, in R/3 a send queue for tRFC was created. This results in the general term qRFC with send queue.

In addition, there are applications that want to determine themselves the exact moment in which to process the LUW in the target system. These are usually applications on an external (non SAP) system that does not have a kind of send queue. qRFC with recipient queue including an appropriate enhancement of the RFC library is currently under development (scheduled for delivery in the next release).

Motivation

What Does tRFC Perform Right Now?

tRFC guarantees that a called function module is executed in the target system exactly once.

All tRFC calls terminated with the statement COMMIT WORK belong to one LUW (Logical Unit of Work). Each LUW automatically receives a transaction ID.

Within an LUW, all function modules are executed in the target system in the sequence in which they are called in the send system.

tRFC calls with the addition AS SEPARATE UNIT map a separate LUW each in the target system. Such a sub LUW contains exactly one tRFC call and is processed independent of the actual (superior) LUW. This sub LUW receives its own transaction ID.

If within an LUW several destinations are used, all tRFC calls that belong to one destination also form a sub LUW. However, since this bundling happens only internally, there is no separate transaction ID assigned to the sub LUW.

Disadvantages of tRFC

tRFC processes all LUWs independent of one another. Due to the amount of activated tRFC processes, this procedure can reduce performance significantly in both the send and the target systems.
In addition, the sequence of LUWs defined in the application cannot be kept. Therefore, there is no guarantee that the transactions are executed in the sequence dictated by the application. The only guarantee is that all LUWs are transferred sooner or later.

Use and Availability

The typical applications for which the serialization of tRFC was implemented use distributed environments:

ALE (Application Link Enabling)

APO (Advanced Planner and Optimizer)

SFA (Sales Force Automation)

qRFC with send queue is released with Release 4.5B.

As a special feature for APO, the serialization is provided as a special release for APO systems of Release 3.1H or 4.5A, respectively .

Other Topics

qRFC With Send Queue: Overview

Programming Serialization

Using "Mixed Mode"

Transaction Sequence and Queue Assignment

Tools