The literature review contains a comprehensive overview of related work performed, including critical analysis of existing software architecture evaluation methods/frameworks used to ensure quality of service in software architecture. It also understands the limitations of existing models and provides motivation for further research in the same field. This chapter has been divided into four subsections based on the specific aspects of the research domain. 2.1 Quality attributes and quality model An important issue in software development today is quality. The non-functional characteristics of a component or system are called quality attributes. “Software quality is defined in IEEE Standard 1061 and represents the degree to which the software possesses the desired combination of attributes”[1]. A software quality model is defined in the draft ISO/IEC 9126-1 [2]. Functionality, reliability, usability, efficiency, maintainability, and portability are the six fundamental categories of software architecture characteristics that are divided into subcharacteristics according to this software quality model. Numerous definitions of quality attributes exist in the literature. For example, the definitions of maintainability, flexibility, and modifiability are described as follows [3]. “Maintainability is a set of attributes that affect the effort required to make specific changes” [2]. Fixes, improvements, or adaptations of the software to changes in the environment, requirements, and functional specifications are part of maintainability. “Modifiability is the ability to make changes quickly and cost-effectively” [4]. There are two types of changes to a system, extensibility, portability, and restructuring. Extensibility or...... half of the article...... CarrieÁre, ªThe method of analysis of architectural compromises,º Proc. Fourth Int. Conf. Eng. of Complex Computing Systems (ICECCS '98), August 1998.[25]. M. Barbacci, S. Carriere, P. Feiler, R. Kazman, M. Klein, H. Lipson, T. Longstaff and C. Weinstock, ªSteps in an Architecture Tradeoff Analysis Method: Quality Attribute Models and Analysis,º Technical Report, CMU/SEI-97-TR-029 ESC-TR-97-029, 1998.[26]. PO Bengtsson and J. Bosch, ªScenario-based Architecture Reengineering,º Proc. Fifth Int. Conf. Software Reuse (ICSR 5), 1998.[27]. PO Bengtsson and J. Bosch, ªForecasting the architecture level of software maintenance,º Proc. Third European Conf. Software Maintenance and Reeng., pp. 139-147, March 1999.[28]. JC Duenas, WL de Oliveira and JA de la Puente, ªA software architecture evaluation model,º Proc. Second International Workshop ESPRIT ARES, pp. 148-157, Feb. 1998.