Restructuring of a node with SDL and MSC

ion levels are closely related to the life-cycle model. Earlier stages of the life cycle model involve expressing higher level abstractions of the system. An example is requirement specification, which express what the system is going to manage at a high abstraction level. In a software system there are often different degrees of abstraction. In a life-cycle model the process goes from a high level to a lower level of abstraction. But there can be different degrees of abstraction in any life-cycle stage. When information is presented in a detailed form at any stage of the life-cycle, there is a low degree of abstraction. When information is presented in a more summarized form at any stage of the life-cycle model, there is a higher degree of abstraction. 3.1.1 Reverse engineering In reverse engineering the process goes from one stage to an earlier stage in the life-cycle model. This means that there is a low abstraction level in the subject system and the system is transformed to a higher level of abstraction. To achieve this, it is necessary to analyze the subject system in order to identify the system’s components and the relation between these components. When this is done the system can be represented in another form, i.e. at a higher level of abstraction. Reverse engineering can be made on a subject system at any stage in the life-cycle. In [P9] they say that one approach to reverse engineering is to first generate a design description from implementation and after this a specification description can be can be generated from the design description. 3.1.2 Redocumentation In redocumentation an alternative view of the system is created at the same level of abstraction. The main reason to perform redocumentation is to recover documentation about the subject system that should have existed. tructuring of a node with SDL and MSC my Nordgren 1999 Page 5