VRC derivation

If a user starts a software component, for example a session, the Virtual Machine (VM) searches from the outside to the inside.

The Virtual Machine (VM) searches for any customizations on the component made by the customer in the own customization. If no own customizations exist, the Virtual Machine (VM) searches for a customer-specific customization, and so on.

This diagram shows how the Virtual Machine (VM) navigates through the customizations on a component. It searches from the outside to the inside.

The search path also depends on the package combination and company to which the user is linked. For example, the package VRCs in a development package combination are derived from the VRCs in the run-time package combination. Those run-time package combinations were, in turn, derived from standard package VRCs.

This diagram shows the derivation structure of the development package combination.

The VRCs with customer extension dev are derived from the VRCs with the cus extension, which themselves are derived from standard VRCs. If a user works with package combination b61O_a_cus and starts a software component. The Virtual Machine (VM) searches for a customization in the VRC with the cus extension. If such a customization is found, this customized component is started. If no such customization exists, the component in the standard VRC is started.

If a user works with package combination b61O_a_dev and starts a software component. The Virtual Machine (VM) searches for a customization in the VRC with the dev extension. If no such customization is found, the Virtual Machine (VM) continues the search in the cus VRC. If this VRC also does not contain a customized version of the component, the Virtual Machine (VM) starts the component in the standard VRC.

If you create many package VRCs, derived from each other, the derivation structure can become complicated.

A cluttered and complicated VRC derivation structure has these consequences:

  • A decrease in system performance due to the longer derivation structure.
  • A cluttered directory structure due to a large number of newly created package VRCs.

The maximum VRC depth, in other words, the number of VRC that you can stack on top of each other, is 40 VRCs. For best results, keep the maximum VRC depth as low as possible.