Consistency in multi-viewpoint architectural design

This thesis presents a framework that aids in preserving consistency in multi-viewpoint designs. In a multi-viewpoint design each stakeholder constructs his own design part. We call each stakeholder’s design part the view of that stakeholder. To construct his view, a stakeholder has a viewpoint. This viewpoint defines the design concepts, the notation and the tool support that the stakeholder uses. The framework presented in this thesis focuses on architectural multiviewpoint design of distributed systems. A distributed system is a system of which the parts execute on different physical system nodes. Interaction between the system parts plays an important role in such systems. An example of a distributed system is a mobile communication network. In such a network, the parts of the system execute on e.g. the mobile telephones of the clients, the desktops of the employees of the network operator and the mobile access points. Architectural design is the area of design that focuses on higher levels of abstraction in the design process. The lowest level of abstraction that we consider is the level at which the system parts correspond to parts that can be deployed on communication middleware. Using our framework, consistency is preserved through inter-viewpoint relations and consistency rules that must be specified by the stakeholders. The stakeholders use inter-viewpoint relations to specify how one view relates to another and they use consistency rules to specify what rules must at least be satisfied in a consistent design. To aid in preserving consistency, our framework defines: – a common set of basic design concepts; – pre-defined inter-viewpoint relations; – pre-defined consistency rules; – a language to represent inter-viewpoint relations and consistency rules. The basic design concepts that the framework defines have been adopted from earlier work. These concepts were developed by carefully examining the area of distributed systems design. Using our framework, viewpoint-specific design concepts must be defined as compositions or specializations of these basic concepts. Hence, the basic concepts form a common vocabulary that the different stakeholders can use to understand each other’s designs. The framework pre-defines inter-viewpoint relations that can be reused to specify how one view relates to another. The two main types of inter-viewpoint relations that it pre-defines are: refinement relations and overlap relations. Refinement relations exist between views that (partly) consider the same design concerns at different levels of abstraction. Overlap relations exist between views that (partly) consider the same design concerns at the same level of abstraction. We derived the pre-defined relations by examining existing frameworks for multi-viewpoint design and extracting frequently occurring relations between viewpoints in these frameworks. If a pre-defined inter-viewpoint relation exists between two views, this implies that certain consistency rules must be satisfied. Specifically, if two views have a refinement relation, this implies that one must preserve the system properties specified by the other. If two views have an overlap relation, this implies that the two views must be equivalent with respect to the overlap that they have. Our framework pre-defines consistency rules that can be re-used to verify these properties. We define an architecture for tool-support to aid in specifying view relations and consistency rules and to check whether the specified consistency rules hold. The architecture contains the pre-defined relations and consistency rules, such that they can be re-used. As a case study for the framework we define adapted versions of the RM-ODP enterprise, computational and information viewpoints, using our framework. We define the concepts from these viewpoints as compositions of the basic concepts. Also, we define the relations between views from these viewpoints, as well as the corresponding consistency rules, using the relations and consistency rules that are pre-defined by the framework. The results of the case study support the claim that our framework aids in preserving consistency in multi-viewpoint designs

Consistency in Multi-Viewpoint

dr. ir. M.J. van Sinderen (Universiteit Twente