| In the practice of software development process, it is increasingly clear that software requirements engineering is the bottleneck of software development. Software requirements engineering consists of a series of requirements related activities, of which an important process is the requirements modeling. Requirements modeling is to derive requirements model of the target system. With requirements model, developers can more accurately understand and express the users’needs and hence verify some functions and characteristics of the system.Regardless of any kind of requirements modeling methods and techniques, as well as other software development methods and techniques, the ultimate goal is to develop a high quality software to meet the needs of users. Whether the software can meet the needs of users depends on the execution of software. Therefore, the correctness of software behavior determines whether software can meet the needs of users. To this end, we have developed a behavior-oriented requirements modeling method, which adopts decomposition method by means of viewpoints and scenarios and establishes a behavior-oriented requirements model (called behavioral model for short) by a formal Behavior Description Language, to elicit and analyze the software behavior during requirements phase.With the requirements model established, developers need to confirm the description in the model meet the users’expect. However, it is still a difficult task for users to read and understand the syntax or even semantics rules of the model. A practicable solution is to use visualization techniques to express the model vividly and hence help users to comprehend the requirements model intuitively. Thus, this paper presents a behavioral model based visualization method, allowing users to watch the dynamic execution of the model visually, and hence assist users of variety background to understand the exact meaning of software behavior. So the users would be more willing to join the requirements verification process and give more effective feedback to improve the efficiency of requirements analysis. These would decrease the requirements change and hence reduce software development costs.The software behaviors of the large software systems are often complicated, in a large number, in different abstract levels and having complex relations. So it is not feasible to describe system behaviors using behavior description language directly. Also, different stakeholders may concern about different abstract level of the system, therefore, the visualization needs to be implemented in different abstract levels. In order to describe the system in different abstract levels and address the needs of multi-level visualization, an effective method is to describe coarse-grained behaviors of higher abstract level system first, then refine these behaviors using refinement technology.Behavior model formally describes the interactions between target software system and problem domains, as well as the interactions between software modules within the system. However, state model is concerned about the state change of single individuals in some abstract levels. So when it needs to research the state change of a single object or a logical module, it is necessary to transform the behavior model to state model. In order to establish the requirements visual model for behavior model, you first need to convert the behavior model to state model. In this paper, we provide a theoretical basis to achieve the automatic conversion of the two models. First, a formal model for state machine is proposed, and then a transformation from behavior model to state machine is presented. The equivalence between the two models is proposed and based on which a series of verification work have been done.At last, an automated teller machine system is presented to illustrate the requirements modeling method and the implementation of visualization, which also including behavior refinement, model transformation and model extraction works. |
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