Software development refers to the type of activity and the process for the creation and maintenance of efficiency, quality and reliability of the software, using the technology, methodology and practice of computer science, project management, mathematics, engineering, and other fields of knowledge. An iterative approach to software development is connected to the work maintaining process with the continuous analysis of the results and the adjustment of previous stages. The project for this approach in every phase of the development is an iterative cycle: plan-do-check-act cycle (Leffingwell, 2000). Therefore, interaction design is the discipline of design, specializing in the design of interactive digital products, systems, environments, and services. The focus of the interaction design is to meet the needs and wishes of the users, in contrast to software engineering, which is taken into account in the first place specifications of the project. There are different interaction design model, however the most popular are waterfall and spiral models, which will be discussed below.
The waterfall model is a model of the software development process, in which the process of developing a flood of consistently passing phases of the required analysis, design, implementation, testing, integration and support. This model was indicated in the article that was published by W. W. Royce in 1970. This model provides a consistent organization of work (Vliet, 2000). Moreover, the main feature is a partition of all the stages of development, and the transition from one stage to the next occurs only after fully completed of the all work in the previous stage. Consider the advantages of waterfall model: at each stage the complete set of design documents is developed that meet the criteria of completeness and consistency; in the final stages user documentation that covers all kinds of standard security information system (organizational, methodological, information, software, hardware) should be developed; logical sequence of stages of work allows to schedule time for completion and associated costs. Disadvantages of this model are: a substantial delay in obtaining results; errors and defects in any of the stages are shown; the complexity of the parallel work on the project; over-saturation of information at each stage; the complexity of project management and high level of risk and uncertainty of investment.
Spiral model, in contrast to the waterfall model involves an iterative process of developing of the information system. This increases the importance of the early stages of the life cycle, such as analysis and design. At these stages is verified and substantiated the feasibility of technical solutions through the prototyping. A spiral approach to software development can overcome most of the shortcomings of the waterfall model, and, in addition, provides a number of additional features, making the development process more flexible. Therefore, the main advantage of the spiritual model in contrast to the waterfall one are: the individual elements are integrated into a single unit; the integration is performed almost continuously; reducing the level of risk. Spiral model provides more reliable and stable system. However, spiritual model has some limitation in contrast to the waterfall one and the main disadvantage is connected to the defining the moment of transition to the next stage.
Therefore, waterfall and spiritual models have different advantages and disadvantages and coming from the previous discussion it is needed to note that limitation of both models can be overcame by the complex usage of both models in the interactional design process.
There are different methods of data collection for the projects. The verity of these methods is determined because of the different situations where some of them are more helpful than others. In the design process the most helpful is data that give complex understanding of the target groups’ tastes. This information can be collected without any surveys or direct observations. For example, this can be done through the services that such people are already used. It should be understood what design target audience prefer by the screening the most popular programs, sites, etc. Another way to understand customers’ needs is to search for information in the social sites and forums where these target audience is being concentrated. Therefore, with the help of forums it is easy to understand the needs and wants of customers, what they prefer in design and what they think the most important and even if it is needed the questions can be asked and the answers will be made by the needed audience. This is one of the most effective methods of the data collection for the software development.