1. A computer system comprised of a computer processor configured for executing program instructions stored in computer memory and arranged for automatic construction of a software package change plan data output, said system comprising: an arrangement for submitting a request for accomplishing a software change to the computer system, wherein the request for accomplishing a software change describes a task to be done on at least one target system and a deadline by which a change needs to be completed; an arrangement for constructing a task graph specifying the order in which tasks accomplishing a software change execute on the system in compliance with data and temporal dependency constraints; an arrangement for creating a software package change plan according to the task graph; wherein the arrangement for creating a software package change plan includes an arrangement for determining operating state transitions that are imposed on software artifacts of the system by execution of the tasks; and further comprising an arrangement for analyzing the software package change plan, whereby the duration of a system service outage caused by a change plan is determined; wherein the software package change plan is used to execute the software change.