Why is scalability important for system developers

1 Part 1: Basics of the V-Model

1.3 Management mechanisms and project implementation

1.3.12 System development

The process modules of the system development area regulate the creation of the functional IT system, which is why they make up a large part of the V-model (see Figure 5 and Figure 6). Nevertheless, the system development can be reduced to a few basic principles. The starting point is a hierarchical structure of the overall system over three levels:

  • TheSystem level describes the requirements for the overall system and how the overall system is divided into the actual system, any support systems and the logistical support documentation.
  • The Segment and unit level describes the breakdown of the system or a support system via Segments away to the level of units. The units are then divided into HW units, SW units and external units.
  • The Component and module level describes the breakdown of a HW unit or a SW unit via Components away to the level of Modules. Modules are the smallest system elements that you have implemented yourself or procured elsewhere and are not subdivided further.

In accordance with this hierarchical system structure, a basically three-stage procedure results. However, since both the client and the contractor consider the system level, the system development process has four stages, as shown in Figure 23. If there is no organizational separation between client and contractor within the framework of the project type system development project (AG / AN), it can make sense to combine the two upper levels again.

Figure 23: Structure of the system creation

The four stages presented also serve as a basis for explaining the three basic tasks in system development: The Specification and disassembly covers the design of the system from the big picture to the smallest detail. This is accompanied by requirements tracking, which seamlessly demonstrates how a requirement affects the individual levels down to the lowest system level. The result of this task are the requirements (specifications), the architectures and the system specifications. The Realization and integration conversely, this includes the implementation and assembly of the system from a single function in a module to a ready-to-use software system. The results are in particular the system elements themselves and the corresponding contents of the Implementation, integration and testing concepts. The Verification and validation includes checking whether the developed system elements correspond to their specification and whether the system is structured as described in the architectures (verification). This check takes place at each of the four levels. In addition, it must be checked whether the created system actually meets the wishes of the user, whether requirements are possibly incorrectly defined and whether important framework conditions have changed during the system development (validation). The results of this task can be found in the relevant Test specifications and Test reports (see discipline examination). The order in which the individual decision points shown are reached depends on the chosen project implementation strategy. Basically, different approaches are provided and meaningful, e.g. an iterative-incremental, a component-based and a prototype development process, which can also be combined with each other in the project.