12 Chapter 2.  State of the Art of Application Development Processes is reached.  In contrast to traditional software-engineering it is important to not only make design modifications that add new functional capabilities but also to thoroughly remove features that do not make sense. Generally, multiple cycles are necessary to start from an initial proposal to a final development based on user feedback. Rapid development cycles:  Many development methods such as extreme pro- gramming [ Beck 2000 ] or rapid prototyping [ Tripp and Bichelmeyer 1989 ] aim at meeting the user’s expectations in short converging cycles. Short and fast cycles are the premise for several iterations during a project life. Use of toolboxes: Toolboxes are a technical prerequisite for rapid developments. Re-using frameworks and architectures over and over again is a key factor for short development cycles. Though re-usability in ubicomp is still in it’s infancy the benefit has been acknowledged and partly addressed for software (e.g.  Context Toolkit [ Salber et al. 1999 ] , Context Fabric [ Hong and Landay 2001 ] ) and hardware (e.g. Smart-Its [ Holmquist et al. 2004 ] ). In general, it will be di cult to design a development process that meets all of the requirements presented above. The requirement, Radically depart from today, and the previous one, (Balanced user involvement), are both central and at the same time create a tension due to their very di erent nature.  Another tension is achieving rapid developments and at the same time integrating multiple stakeholders which requires cooperation with di er- ent party and may be time consuming.  Moreover, supporting early stage develop- ments and simultaneously aiming at feasible results requires rich opportunities of prototyping and implementing concepts.  Due to the early stage of toolboxes and reusable frameworks in ubiquitous and wearable computing, in many cases applica- tion developers will still have to deal with many technical implementation issues. However, assuming further advancements in the near future will help to free develop- ers from those technological issues and allow them to better focus on the development and concept generation. In  our  opinion  any  successful  method  has  to  respect  these  tensions.   When  these tensions can be well integrated into an overall process it can create and stimulate highly novel and innovative ideas and applications. The  presented  requirements  will  be  used  in  the  following  sections  to  discuss  the strengths and shortcomings of various prominent development processes. 2.2   Review of Existing Development Processes This section reviews processes leading towards innovative developments.  It starts with the well established and traditional field of software-engineering and continues