1. A method of controlling a software maintenance process in a software system landscape having a plurality of logical systems, the method comprising: determining a current phase of the software maintenance process, each phase of the software maintenance process defining actions allowed, required, or not allowed to be performed; receiving, at a phase controller, a request generated by and received from an independent service software component of a plurality of independent service software components requesting allowance to perform an action, the plurality of independent service software components to perform actions of the software maintenance process for servicing the logical systems; storing a customized algorithm for each of the independent service software components at the phase controller upon initial registration of each of the independent service software components with the phase controller, the customized algorithm used in automatically determining whether an intended action is allowed by describing actions to be taken for each of the independent service software components; automatically and without human intervention, determining, using the phase controller and the customized algorithm stored at the phase controller for the independent service software component, whether to allow the action based on the current phase of the software maintenance process and on phase definitions of the current phase comprising allowed or barred actions; and allowing or denying the action based on the determining performed by the phase controller.