In AUTOSAR, the ECU software is classified as basic software (BSW), runtime environment (Rte) and application layer.
Basic elements of the AUTOSAR architecture are, among others, formally defined software components (SWC) with clearly specified interfaces to the basic software (BSW) that in turn provide fundamental standard services, such as bus communication, memory management, IO-access, system and diagnostic services. Another basic element is the runtime environment RTE that connects the SWCs with the BSW.
The Virtual Functional Bus (VFB) specified by AUTOSAR delivers the conceptual foundation for the communication of SWCs with each other and the use of BSW services. The development of the SWCs is based on the VFB. In this manner, the SWCs are independent of the ECU hardware. This makes them easier to reuse and integrate into different projects on different platforms. The VFB is implemented in a specific vehicle by using a specifically configured RTE together with a suitably configured BSW for each ECU.