1.5　Structure of the book

The rest of the dissertation is organized as follows.

Chapter 2 pursues requirements analysis for the problem domain: the middleware for mobile systems. After developing the conceptual framework for understanding and describing the middleware, we illustrate the framework with some existing middleware examples. Afterwards, we conclude the aspects to be modeled, generalize commonalities for a class of related middleware. The results will be used to construct the architectural style of the middleware in the following chapters.

Chapter 3 at first identifies the detailed requirements for the architecture centric approach, which are classified into two groups: style specification and modeling languages. We then review related work against these requirements, revealing existent achievements and open problems.

Chapter 4 gives an overview of our style-based approach after introducing the concept of the new style. We generalize the approach as a modeling and simulation framework, which structurizes the approach into several main parts: modeling language, style, style refinement and style simulation. We put the consistency check under simulation since it is developed based on the support of simulation. The next chapters follow this structure and explain each of these parts.

Chapter 5 explains the TGTS based modeling language, which includes the related background knowledge and how to model the required aspects of the style.

Chapter 6 illustrates the process of developing the style through constructing a concrete style as an example: the style of the middleware for nomadic networks. The style captures the commonalities of the class of related middleware, which are already concluded in Chapter 2 during the requirements analysis. In order to decrease complexity and enhance reusability, we separate the style on three different abstract layers, i.e., the conceptual style, the platform-independent concrete style and the platform-specific concrete style. Each of the style captures different architectural aspects or views. They are associated by refinement relationship. We take a concrete middleware,Wireless CORBA, as the example of the platform-specific concrete style.

Chapter 7 is about the refinement. We start with the detailed requirements for the refinement, which contain the properties to be preserved. The existing approaches and open problems are discussed. Afterwards, we explain how to correctly refine a TGTS-based abstract architectural style to a concrete one. We also check whether the requirements are fulfilled.

Chapter 8 clarifies the consistency check and simulation. We explain at first the framework for behavioral consistency check. After evaluating the suitability of existing graph transformation tools, we explain how to use Fujaba environment to specify and simulate the style. We illustrate then three ways to use Fujaba simulation for further style-based analysis and automation:to validate the model efficiently, to automate the refinement consistency check, and to automate behavioral consistency check. Finally, we summarize the style-based engineering process that helps the design and development of the style.

Chapter 9 concludes the thesis. We evaluate the results against the requirements listed in Chapter 3, explain the relevance to practice, summarize the contributions, and give an outlook on future work.

Bibliographical note

Preliminary results of this work have already been published in [63, 64, 72, 65].