Background communication is a term used to describe various asynchronous communication methods. With all the methods, the data that is exchanged between calling and called applications is recorded in the database. The database can be used both by the caller and the called application.
From the database, the data is transferred according to either the push principle or the pull principle. With the push principle, the transfer from the database is triggered by one or more schedulers. With the pull principle, the receiver (the called application) collects the data from the database on its own. This procedure is also known as a no-send scenario in SAP terminology.
In all cases, the system ensures the data is transferred once only with all the procedures ( exactly once or transactional in SAP terminology). The caller can also determine precise adherence to the call order when the data is transferred to the called application ( exactly once in order or queued in SAP terminology).
Three current methods of background communication are described in the sections below:
qRFC ( queued remote function call)
bgRFC ( background remote function call)
LDQ ( local data queue)
bgRFC and LDQ are the successors of the methods qRFC and tRFC. Unlike tRFC and qRFC, bgRFC and LDQ offer the following advantages:
Less use of system resources
More detailed configuration options
Clear functional separation between the push and pull principles, as well as between the transactional and queued methods.
Better for the developers in terms of their complete, object-oriented API and their integration into the ABAP programming language
With the bgRFC, solutions can be developed that process either transactional or queued methods in accordance with the push principle.
The LDQ offers a queued method in accordance with the pull principle.
SAP strongly recommends not using the qRFC ( queued, push principle), the qRFC no-send ( queued, pull principle), or the tRFC ( transactional, push principle) in new applications on the basis of the disadvantages described above.