Overview on Requirements Change Management Methods. In general, a portfolio of different methodologies is used together for the requirements process depending on the chosen software development method. In this sections we will discuss some existing approaches for the software development process, such as the waterfall model [1], the Agile Alliance model [2] and the spiral model [5]. An important relationship regarding the discussion of methods is the connection between the chosen software development approach, which will be used for the development of the IoT reference architecture and the associated change management; the method used for requirements management in IoT-A must be as flexible as the architecture development methods. A description of common change management methodologies are as follows: • The Waterfall Model: The waterfall model describes the software development process as a sequential, linear and predictable process. It begins with a complete analysis of the requirements from the user perspective and is followed by design, development, and organized shipment. If a phase is completed, it is not possible to return to a previous phase of the process. This means within the IoT-A project a change of the initial requirements set or only a change of the priority of a requirement would not be supported. The main advantage of the waterfall model is that it provides a kind of stability [3]. Nevertheless, experience has shown that this software development model is applicable in a stable environment which is less affected by market dynamics. In a changing environment, as in the IoT-A research project, the waterfall model doesn’t provide the possibility to react in a constantly changing market situation [4]. Innovations of these early methods brought a variety of publications, such as the ones of Xxxxx [5], who is known for his spiral model and other developments such as the V- model. In the 90s the new software management approach called" Agile Movement" [6] was published [7], influenced by the development of object-oriented programming and Internet technologies. • The Spiral Model combines aspects of iterative prototyping in stages with the design sequences of the waterfall method. The general steps can be defined as follows: • In the beginning, the system requirements are defined in as much detail as possible by contacting external and internal stakeholders • A preliminary design is created for the new system, based on analyzing alternatives and reviewing works in the state-of-the-art • A first prot...
