1. A computer implemented method for connecting business objects in a software application (SA), wherein the software application comprises a connector (K), wherein the connector comprises an identifier identifying an abstract business object class (ABO 1 to ABO n ), the software application, during runtime, determines the abstract business object class indicated by the connector in a hierarchy of abstract business object classes, and the software application is executed by a processor, and during runtime starting from the determined abstract business object class, determines at least one concrete business object class (KBO 1 to KBO n ) derived therefrom directly or indirectly, and establishes a connection (V) to at least one instance (I 1 to I n ) of the at least one determined concrete business object class, via which the software application accesses attributes and methods of the at least one instance of the at least one determined concrete business object class, wherein the at least one determined concrete business object class (KBO 1 to KBO n ) is connected to at least one external software system (ES) via an adapter (A), in which characteristics of the concrete business object class are stored, wherein the at least one instance (I 1 to I n ) of the at least one determined concrete business object class (KBO 1 to KBO n ) is connected to at least one external software system (ES) via an adapter (A), in which characteristics of the at least one instance are stored, wherein the adapter (A) receives method calls of the at least one determined concrete business object class (KBO 1 to KBO n ) or the at least one instance (I 1 to I n ), transforms these method calls into instructions executable by the external software system (ES), and transmits the executable instructions to the external software system, wherein an abstract business object class implements a method, by means of which instances of the at least one determined concrete business object class derived from this abstract business object class directly and/or indirectly may be accessed, and wherein the method comprises determining of the instances and transmitting the determined instances to the software application.