You can install a central system on a single host.

These are the following instances:

• ABAP central services instance (ASCS instance)

  • SAP recommends installing the ASCS instance because this enables you to cluster the message server and enqueue server separately from the central instance.

    However, you can also install your SAP system without the ASCS instance. In this case, follow the instructions in Installing a Central or Distributed System Without the ASCS Instance.

  • Optionally you can install the ASCS instance with an integrated SAP Web Dispatcher. For more information, see ASCS Instance with Integrated SAP Web Dispatcher.

• Central services instance (SCS instance)

• Database instance (DB instance)

  The ABAP stack and the Java stack use their own database schema in the same database

• Central instance

Additionally, you can install one or more dialog instances. For more information, see Dialog Instance.

The following figure shows an example of SAP instances in a central system.

Figure 1: Central ABAP+Java System